AB-903_telescopic_mast_serv_user_TM11-5985-263

TM 11-5985-263-15
DEPARTMENT OF THE ARMY TECHNICAL MANUAL
OPERATOR'S, ORGANIZATIONAL, DIRECT SUPPORT,
GENERAL SUPPORT, AND DEPOT MAINTENANCE
MANUAL
INCLUDING REPAIR PARTS
AND SPECIAL TOOL LISTS
MAST AB-903/G
(NSN 5985-00-933-2197)
This copy is a reprint which includes current
pages from Changes 1 and 2. The title
was changed by Change 2.
H E A D Q U A R T E R S, D E P A R T M E N T O F T H E A R M Y
MAY 1970
TM 11-5985-263-15
CONDENSED OPERATING INSTRUCTIONS
FOR ANTENNA MAST AB-903/G
TO RAISE MAST, HAND-OPERATED:
1.
REMOVE PIN A .
2.
RELEASE SPRING RETAINER B.
3.
EXTRACT LOCKING PIN C AND ROTATE 90° TO LOCK-OUT POSITION.
4.
CRANK HANDLE D IN DIRECTION SHOWN.
CAUTION:
DO NOT RAISE MAST TO FULL HEIGHT IF WINDS
ARE IN EXCESS OF 35 MPH OR MAST IS OUT OF
VERTICAL POSITION BY MORE THAN 7°.
5.
CRANK APPROXIMATELY 54 TURNS TO FULL UP POSITION.
6.
LOCK THE MAST IN UP POSITION WITH LOCKING PIN C .
TO LOWER MAST, HAND-OPERATED:
7.
EXTRACT LOCKING PIN C AND ROTATE 90° TO LOCK-OUT POSITION.
8.
CRANK HANDLE D IN DIRECTION SHOWN.
9.
CRANK UNTIL DESIRED POSITION IS REACHED.
10.
ENGAGE LOCKING PIN C .
EL5985–263-12-TM-11
Condensed operating instructions for Antenna Mast AB–903/G.
①
WARNING
Contact between the antenna elements, antenna mast, and high voltage sources must be avoided at all
times. Maintain a safe distance (twice the height of the antenna) when erecting and operating the
antenna in the vicinity of high-tension lines. Make sure that all instructions covering whip antennas
and antenna masts detailed in TB SIG 291 are met before attempting to erect or operate the antenna
equipment.
*TM 11-5985-263-15
HEADQUARTERS
DEPARTMENT OF THE ARMY
W ASHINGTON , DC, 20 May 1970
T ECHNICAL M A N U A L
No. 11-5985-263-15
OPERATOR, ORGANIZATIONAL, DIRECT SUPPORT, GENERAL
SUPPORT, AND DEPOT MAINTENANCE MANUAL
MAST AB-903/G (NSN 5985-00-933-2197)
C HAPTER 1.
Section I.
II.
C HAPTER 2.
Section I.
II.
III.
C HAPTER 3.
4.
Section I.
II.
C HAPTER 5.
6.
Section I.
II.
C HAPTER 7.
8.
9.
Section I.
II.
A PPENDIX A.
B.
Section I.
II.
C.
Section I.
II.
III.
IV.
A PPENDIX D.
INDEX
Paragraph
INTRODUCTION
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 – 1-3
Description and data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4 – 1-10
INSTALLATION
Service upon receipt of equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-1, 2-2
Ground-mounting installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3 – 2-7
Counterpoise assembly and Antenna AS-1729/VRC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-8, 2-9
OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-1, 3-2
OPERATOR AND ORGANIZATIONAL MAINTENANCE
Operator’s maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1 – 4-6
Organizational maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-7 – 4-13
MECHANICAL FUNCTIONING OF MAST AB-903/G . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1 – 5-5
DIRECT SUPPORT MAINTENANCE
Maintenance instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1 – 6-6
Testing procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-7, 6-8
GENERAL SUPPORT MAINTENANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-1 – 7-8
DEPOT MAINTENANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1, 8-2
SHIPMENT, LIMITED STORAGE, AND DEMOLITION
TO PREVENT ENEMY USE
Shipment and limited storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-1, 9-2
Demolition of materiel to prevent enemy use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-3, 9-4
REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BASIC ISSUE ITEMS
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-1 – B-3
Basic issue items list . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MAINTENANCE ALLOCATION
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-1 – C-4
Maintenance allocation chart for Mast AB-903/G . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tool and test equipment requirements for Mast AB-903/G . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Remarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Deleted
........................................................................................
Page
1-1
1-1
2-1
2-1
2-5
3-1
4-1
4-2
5-1
6-1
6-2
7-1
8-1
9-1
9-2
A-1
B-1
B-2
C-1
C-3
C-4
C-5
I-1
*This manual supersedes TM 11-5985-263-12, 14 August 1967
Change
2
i
Figure 1-1. Mast AB-903/G, less ground-mounting components.
Change 2
1-0
TM 11-5985-263-15
CHAPTER 1
INTRODUCTION
Section 1. GENERAL
1-1. Scope
a. This manual describes Mast AB-903/G (fig. 1-1)
and covers its installation, operation, direct and
general support, and depot maintenance.
b. The basic issue items list appears in appendix
B, the maintenance allocation chart appears in
appendix C, and the repair parts and special tool
lists appear in TM 11-5985-263-34P.
NOTE
Appendix C is current as of June 15 1978.
Appendix B is current as of 5 May 1973.
1-2. Indexes of Publications
a. DA Pam 310-4. Refer to the latest issue of DA
Pam 310-4 to determine whether there are new
editions, changes, or additional publications pertaining to the equipment.
b. DA Pam 310-7. Refer to DA Pam 310-7 to
determine whether there are modification work
orders (MWO’s) pertaining to the equipment.
1-3. Forms and Records
a. Reports of Maintenance arid Unsatisfactory
Equipment. Maintenance forms, records, and reports which are to be used by maintenance
personnel at all maintenance levels are listed in
and prescribed by TM 38-750.
b. Report of Packaging and Handling Deficiencies. Fill out and forward DD Form 6 (Packaging
Improvement Report) as prescribed in AR 700-
58/NAVSUPINST 4030-29/AFR 71-13/MCO
P4030.29A, and DSAR 4145.8.
c. Discrepancy in Shipment Report (DISREP)
(SF 361). Fill out and forward Discrepancy in
Shipment Report (DISREP) (SF 361) as prescribed
in AR 55-38/NAVSUPINST 4610.33B/AFR 75-18/
MCO P4610.19C and DLAR 4500.15.
1-3.1. Reporting of Errors
The reporting of errors, omissions, and recommendations for improving this publication by the
individual user is encouraged. Reports should be
submitted on DA Form 2028 (Recommended
Changes to Publications) and forwarded direct to
Commander, US Army Communications and Electronics Materiel Readiness Command, ATTN:
DRSEL-ME-MQ, Fort Monmouth, NJ 07703.
1-3.2. Reporting Equipment Improvement
Recommendations (EIR)
EIR’s will be prepared using Standard Form 368,
Quality Deficiency Report. Insturctions for preparing EIR’s are provided in TM 38-750, the Army
Maintenance Management System, EIR’s
should be mailed direct to Commander, US Army
Communications and Electronics Materiel Readiness Command, ATTN: DRSEL-ME-MQ, Fort
Monmouth, NJ 07703. A reply will be furnished
direct to you.
Section Il. DESCRIPTION AND DATA
1-4. Purpose and Use
a. Mast AB-903/G provides the means to raise
such antennas as Antenna AS-1729/VRC 30 feet
above ground level. The retracted height of the
mast is 72 inches. The mast may be set up on the
ground, or mounted on vehicles. The mast maybe
raised to full height by handcranking.
b. Figure 1-1 illustrates the general arrangement of the mast on the ground.
1-5. Technical Characteristics
Height retracted . . . . . . . . . . . . . 6 feet.
Height extended . . . . . . . . . . . . . 29 feet, 3 inches.
Method of extending mast. . . . Cable-driven telescope
tubular sections
activated by crank handle.
Time required to raise mast 25 seconds by hand.
(after installation of
group).
Tube sizes . . . . . . . . . . . . . . . . . . . 4 1/4-inch diameter to
1 1/2-inch diameter.
Number of tubular segments. 6.
Installation provisions . . . . . . . Ground or vehicular.
Number of guys . . . . . . . . . . . . . 6 for ground installation.
Number of stakes . . . . . . . . . . . . 3.
Material . . . . . . . . . . . . . . . . . . . . . Aluminum alloy tubing,
corrosion-resistant
cables and hardware,
aluminum alloy mounting
brackets, Dacron guy
ropes.
Weight:
Mast . . . . . . . . . . . . . . . . . . . . . .40 pounds.
14.75 pounds.
Mounting brackets, guys,
anchors.
Maximum wind loading . . . . . .35 mph without top guys;
50 mph with top guys.
Load limitation . . . . . . . . . . . . . .20 lb masthead load over
area of 2 square feet
(Maximum allowable load
on extended mast).
Change 2
1-1
TM 11-5985-263-15
1-6. Table of Components
The components of Mast AB-903/G are listed in the
following table (figs. 1-2 and 1-3):
Dimensions (in.)
Quantity
1
3
3
1
3
1
1
1
1
a
Height
Item
Mast assembly (FSN 5985-933-2197). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
a
Guy assemblies, lower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Guy assemblies, upper a . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
a
Basplate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
a
Stake, guy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Adapter, antenna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
a
Handle, crank . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Bag, accessory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
a
Hammer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
72
23 ft
42 ft
1 5/8
18 1/2
8
8 3/4
10
...
Depth
Unit weight
Width
5
...
...
6
2
...
5 1/2
12
9
...
...
6
2
3
1 1/4
21
...
...
(lb)
40.0
0.3
0.6
0.4
1.25
.3
1.0
2.75
2.25
Indicates item is contained in accessory bag.
NOTE
Where ground stakes are used in arctic
regions, a hammer has been provided to
aid in driving the stakes into the ground.
1-6.1. Items Comprising an Operable Mast AB-903/G
FSN
Qty
5985-933-2197
5985-089-5020
5985-089-5610
5985-933-2193
5985-933-2187
5985-089-5618
5985-914-8055
5985-933-2188
Nomenclature, part No., and mfr code
Fig.
The part number is followed by the applicable 5-digit Federal supply code for manufacturers
(FSCM) identified in SB 708-42 and used to identify manufacturer, distributor, or
Government agency, etc.
Mast AB-903/G: 1054-101; 81868 (This is nonexpendable which includes):
Adapter Antenna: (1 ea), 1054-401-1; 81868
Cable Counterpoise: (1 ea), 1054-403-1; 81868
Guy, Lower: (3 ea), 1054-301-1; 81868
Guy, Upper: (3 ea), 1054-301-2; 81868
1-3
Plate, Base, Mast: (1 ea), 1054-303-1; 81868 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Stake Assembly, Guy: (3 ea), 425-658-1; 81868 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
Tube Counterpoise: (3ea), 1054-402-1; 81868 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-7
Tube Counterpoise: (1 ea), 1054-402-2, 81868
1-7. Description of Mast AB-903/G
a. Mast AB-903/G (figs. 1-1, 1-2, and 1-3) is a
cable-driven, lightweight, telescope mast assembly. A crank handle attached to the winch
assembly is used to raise or lower the mast. The
1-2
Change 2
cable inside the winch assembly raises only the
largest movable diameter mast section. Each of
the other sections are independently connected by
cables. The raising of this largest sec-
TM 11-5985-263-15
tion exerts pressure on an independent set
of cables connecting to the second largest
mast section which, in turn, causes it to
raise. The second largest section raises
the third largest section in a similar manner, and the third section raises the fourth
largest section. The fourth largest raises
the fifth largest (smallest diameter) section to which the appropriate antenna mount
is attached. The motion is cumulative, and
as a result, the section to which the antenna mount is connected moves most
rapidly, and the largest diameter section
moves most slowly. Operation will clearly
show how the motion is transferred from
one mast section to the other. Operation is
discussed in paragraph 3-2.
b. Other features of the mast are the
locking pin (fig. 3-1) and the winch brake
(fig. 5-2). Inside the winch assembly is a
winch brake which is so designed that when
the mast is being raised no pressure is
exerted on the winch mechanism; however,
whenever the mast tends to lower, either
from the weight of the antenna and antenna
mount, or when being cranked down, the
winch brake applies pressure to the winch
mechanism, preventing the mast from being
lowered too rapidly and keeps it at any
stopped height. The locking pin is used to
lock the mast in any position; that is, fully
erected, fully lowered, or any position in
between.
c. When the mast is being transported
or stored, a toggle-lock mechanism with a
spring and a stop (safety) pin (fig. 1-4) are
used to secure all mast sections to prevent
unnecessary movement between the mast
sections. The mast may be locked only when
it is fully retracted.
d. The mast may be used in ground installation or in vehicular operation. Ground
installation and operation will be discussed
in this manual. A typical vehicular installation in a M151A1 vehicle is shown in figure 1-2. For detailed vehicular installation,
refer to pertinent manual for that vehicle.
1-8. Description of Minor Components
Included with the mast are the following
minor components:
a. A canvas accessory bag for storing
components when not in use.
b. A base plate required for ground installation.
c. Three ground stakes.
d. Three upper and three lower guy assemblies.
e. A crank handle.
f. H a m m e r .
Change 1
1-2.1
TM 11-5985-263-15
Figure 1-2. Typical vehicular installation of Mast AB-903/G.
1-3
TM 11-5985-263-15
Figure 1-3. Mast AB–903/G and ground-mounting components.
1-9. Additional Equipment Required
The counterpoise adapter unit, required in certain uses with the mast, is also supplied as
part if the AB–903/G. Omnidirectional Antenna
AS-1729/VRC may be mounted on Mast AB–
903/G. To improve the radiation pattern of the
antenna, a counterpoise assembly is provided to
be attached to the counterpoise adaptor unit.
Procedures for assembling the complete counterpoise assembly are discussed in paragraphs 2-8
and 2-9.
1-10. System Application
a. Omnidirectional Usage. The best reception
and transmission of signals occur with the greatest height of the antenna. This is particularly
true in the very high frequency (vhf) range
1-4
where signals are restricted by line-of-sight characteristics. Mast AB–903/G is used mainly with
vhf radio systems. Its 30-feet extended height
increases distance of transmission and reception, except in dense foliage. In dense foliage and
jungles, other means must be taken to raise the
antenna and the mast above the foliage to achieve
efficient signal propagation. Refer to the applicable technical manual for these considerations
in system application.
b. Directional Antenna Use. Directional antennas, such as the log periodic type, incorporate
design features which increase the distance,
range, and strength of most signals. Some of
these antennas can be used with the mast, but
are limited to a 20-pound masthead load. Antennas in excess of this weight can damage the mast
TM 11-5985-263-15
Figure 1-4. Mast AB–903/G, counterpoise assembly, and mast-securing components.
and should not be used. Use of these antennas,
coupled with the extended 30-foot height of the
mast, permits reception and transmission of
signals, particularly in the vhf range, where
other antennas of the omnidirectional type can.
not be used. This, however, does not reduce the
problem when attempting to send or receive
signals in densely wooded areas or jungles. Also,
the antenna used should be properly aimed in
the direction of transmission or reception before
raising the mast and the antenna; however, di-
rection can be changed after the mast is erected.
Refer to applicable technical manual of the particular radio set for further considerations in
system application.
c. Vehicular Use. The mast can be mounted
on the following vehicles: M–114 Carrier, M-577
Carrier, M151A1 Truck, M-37 Truck, and M-109
Truck. Each of these vehicles has a designated
area for storing the mast during transit when
not in use, and a bracket for mounting the mast
while in use.
1-5
TM 11-5985-263-15
CHAPTER 2
INSTALLATION
WARNING
During installation of this equipment, conform to all safety requirements
set forth in TB SIG 291. Injury or death could result from failure to comwith safety practices.
Section I. SERVICE UPON RECEIPT OF EQUIPMENT
2-1. Unpacking
a. Packaging Data. When packed for shipment, the components of Mast AB-903/G
are packed in a nailed, wooden box. In the
wooden box are two fiberboard boxes: one
contains the mast and the other contains
the canvas accessory bag in which the
ground-mounting components are stored.
The counterpoise tube assembly is stored
inside the innermost mast section; all other
components are found in the accessory bag.
b. Removal of Contents. P e r f o r m t h e
procedures given below.
(1) Cut and fold back the metal straps.
CAUTION
Do not pry deeply into the wooden
box. Components inside the box
may become damaged.
(2) Remove the nails from the top and
one side of the box with a nailpuller. Remove the top and one side. Remove both
fiberboard boxes.
(3) Open the moistureproof barrier
that covers each fiberboard box. Open each
box.
(4) Open the moisture-vaporproof barrier inside each fiberboard box. Remove
the inner carton. Open the inner carton and
remove the contents of both cartons.
2-2. Checking Unpacked Equipment
a. Inspect the mast and accessories for
damage incurred during shipment. If the
equipment has been damaged, report the
damages as prescribed in paragraph 1-3.
b. Check to see that the equipment is
complete as listed on the packing slip. Report all discrepancies in accordance with
AR 735-11-2. Shortage of a minor assembly
or part that does not affect proper functioning of the equipment should not prevent
use of the equipment.
c. If the equipment has been used or reconditioned, check to see whether it has
been changed by a modification work order
(MWO). If the equipment has been modified,
the MWO number will appear near the nomenclature plate. Check to see whether the
MWO number (if any) and appropriate notations concerning the modification have been
entered in the equipment manual.
NOTE
Current MWO’s applicable to the
equipment are listed in DA Pam
310-7.
Section II. GROUND-MOUNTING INSTALLATION
2-3. Selection of Site
the guy lines.
a. Mast AB-903/G may be erected on
any site where adequate clearance is available. The antenna, mast, and guy lines must
be free from overhead obstructions, such
as trees or powerlines.
2-4. Orientation of Mast and Antenna
b. The site selected should have firm
soil to hold the guy stakes in place. In
areas where the soil is sandy or wet and
stakes tend to shift in the soil, small trees
or stumps may be used for attachment of
There are no special considerations for
orienting the antenna mounted on Mast AB903/G if the antenna is omnidirectional. A
typical antenna, such as Antenna AS-1729/
VRC, radiates energy in all directions and
is merely attached to the end of the mast
as directed. Instructions for mounting the
AS-1729/VRC are given in paragraphs 2-8
and 2-9.
Change 1
2-1
TM 11-5985-263-15
2-5. Mast Components for Ground
Installation
c. Counterpoise Assembly. The complete
counterpoise assembly is described in paragraph 2-8. Procedures for assembly of the
counterpoise are given in paragraph 2-9.
stake is facing toward the base plate.
NOTE
In e, f, and g below, mast may be
either erected, lying down, or supported at any angle in between these
extremes.
e. Release the toggle lock (fig. 1-4) that
holds the telescopic mast sections together
during transit. (The safety pin from the top
mast section has already been removed).
Lift off the restraining spring from the toggle lock attachment extension (fig. 5-4).
f. U n c o i l t h e t h r e e l o w e r g u y r o p e s .
Attach the hook to the lower guy attachment
ring on the mast. Attach the other end to
the hook on the stake. DO NOT tighten the
guys at this time.
g. Uncoil the three upper guy ropes.
Attach the hook to the upper guy attachment plate and let the other end hang loose.
DO NOT fasten guys to stakes or attempt to
tighten guys at this time.
2-6. Preparation for Mast Setup
2-7. Erecting Mast
a. Tools Required. No special tools are
required for ground installation of Mast
AB-903/G. A hammer is supplied for driving ground stakes into the ground.
b. Components Required. The following
components are required for ground installation of Mast AB-903/G:
Quantity
1
1
3
3
1
3
1
Item
Fig. No.
Mast AB-903/G . . . . . . . . . . . . . . . . . . .1-3
Crank handle . . . . . . . . . . . . . . . . . . . .1-3
Guy assembly, upper . . . . . . . . . . . . . . . 1-3
Guy assembly, lower . . . . . . . . . . . 1-3
Base plate . . . . . . . . . . . . . . . . . . . . . 1-3
Ground stake . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
Hammer . . . . . . . . . . . . . . . . . . . . . . .1-3
a. Remove the components from the canvas accessory bag. Remove the protective
cap and counterpoise tubes from the innermost tube of the mast by removing the
safety pin (fig. 1-4) and lifting the cap from
inside the mast.
b. Before erecting the mast, position the
base plate on the mast. Set the base plate
(fig. 1-3) firmly on the ground at the desired mast location so that the bent corners
dig into the ground.
NOTE
Ground should be as level as possible.
c. Locate the three guy stakes by pacing
off approximately 18 feet from the base
plate. This distance is the line from mast
to the edge of an imaginary circle (radius);
around this i m a g i n a r y circle, place the
stakes 120° apart (one-third of the way
around for each stake). Refer to figure 2-1.
NOTE
If the ground is level, and if a radius
of 18 feet is used, the distance
from one stake to any other stake
will be between 31 and 32 feet. This
provides a rule of thumb to see if
the stakes are spaced equally
apart.
d. Drive each of the stakes into the
ground at approximately a 60° angle (that
is, 60° facing away from the mast) (fig.
2-1). Insure that the hook on the ground
2-2
Change 1
CAUTION
Be careful that counterpoise and
antenna elements do not injure personnel. Counterpoise tubes and antenna elements have sharp points
and could cause serious personal
injuries.
a. Insure that the applicable antenna a s sembly is dated correctly on the mast b e fore raising the entire mast assembly on
the base plate. The mast may be placed into
position first; then, place the antenna assembly on the mast as required. Antenna
adaptor is locked to the masthead with the
securing pin.
b. Be sure that the mast is on the base
plate so that the square hole in the bottom
of the mast (fig. 2-2) engages the square
projection on the base plate (fig. 1 -2). Be
sure that the mast is held vertically; use
any necessary manpower until the lower
guy ropes are secured to keep the mast
erect.
c. Gradually tighten the lower guy ropes
by sliding the rope snubbers until the mast
is vertical. The lower guy plate is shown
in figure 5-4.
NOTE
Mast must not be tilted more than
7° to avoid excessive loading on the
fully raised mast sections.
TM 11-5985-263-15
Figure 2-1. Stake-plotting plan, ground installation Mast AB-903/G.
2-3
TM 11-5985-263-15
Figure 2-2. Mast AB-903/G, bottom plate (base cap).
d. The mast is not designed to be raised or
lowered if winds are in excess of 35 miles per
hour. If the mast is raised or lowered during
windy periods, protect the mast by insuring that
the upper and lower guy lines are held snug.
This can be done by handholding the upper
lines as the mast is raised.
2-4
e. After the mast has been raised as described
in paragraph 3–2, insure that the upper guys are
secure by sliding the rope snubbers; make sure
that the mast is vertically straight. The upper
guy plate is shown in figure 3–2.
TM 11-5985-263-15
Figure 2-3. Counterpoise tubes and wires, assembly procedures.
Section III. COUNTERPOISE ASSEMBLY AND ANTENNA
AS-1729/VRC
2-8. General
(figs. 2-3 and 2-4)
Mast AB–903/G is shipped with counterpoise
adapter unit and counterpoise tube assembly to
allow use with Antenna AS-1729/VRC. Antennas to be used with Mast AB–903/G have their
own mounts which are issued as a part of the
antenna. This section has been prepared to provide information for assembly of units using a
counterpoise adapter unit and counterpoise tube
assembly. The complete counterpoise assembly
consists of the following items.
2-5
TM 11-5985-263-15
Figure 2-4. Diagram of complete counterpoise assembly, top view.
Quantity
1
3
1
1
1
Item
Counter poise adaptor unit . . . . . .
Counterpoise tube (w/o rubber
fasteners).
Counterpoise tube (w/rubber
fasteners).
Counterpoise wire . . . . . . . . . . . . . . .
Antenna AS-1729/VRC.
References
Fig. 1-3
Fig. 1-4
Fig. 1-4
Fig. 1-3
2–9. Assembly of Counterpoise Tubes on
Antenna Adapter
NOTE
The counterpoise adaptor unit is specifically designed so that Matching Unit
Base MX–6707/VRC, part of Antenna
AS-1729/VRC, may be attached to the
counterpoise adaptor unit. If any other
type of antenna is to be mounted on
Mast AB–903/G, refer to the applicable
technical manual.
CAUTION
Do not overtighten bolts; damage to
components may result.
a. Attach Mounting Unit Base MX–6707/VRC
to the counterpoise adaptor unit (figs, 1–3 and
2-6
5-5) with the two bolts screwed into the holes
provided for this purpose.
b. Remove and separate the four counterpoise
tubes stored in the mast. Two rubber fasteners
will remain attached to one of the tubes which
has a double clip at one end. Each of the three
remaining tubes has a single clip. Insert the
blunt end of each tube into each of the four
sockets in the counterpoise adaptor unit. The
counterpoise tubes will automatically snap into
position.
CAUTION
Overtightening of the counterpoise wire
can bend the tubes.
c. Remove the counterpoise wire from the accessory bag. Insert the counterpoise cable into
one clip of the tube that has a double clip (fig.
2-3). Run the cable to the nearest tube that
has a single clip. Insert the cable into the single
clip; make sure that the counterpoise wire is
taut.
d. Continue looping the counterpoise wire around the single clips of the remaining sections
(B, and C, fig. 2-3) until the cable terminates
TM 11-5985-263-15
at the double clip counterpoise tube (D, fig. 2-3).
Refer to figure 2–4 for a diagram of the completed assembly. Place the counterpoise securing tape in the canvas bag for safekeeping.
e. Screw Antenna Element AT–1095/VRC into Antenna Element AS-1730/VRC. Hold the
counterpoise assembly with Matching Unit Base
MX–6707/VRC attached and place the threaded
end of the AS-1730/VRC into the matching base;
turn until secure. Insert the completed assembly
into the top mast section. Refer to TM11–5985–
262–15 for correct antenna cable connections.
The antenna can be raised into position by
cranking the mast to the desired extended position after connecting the applicable cables. Use
cable grip PF–211/G to support the cables.
2-7
TM 11-5985-263-15
CHAPTER 3
OPERATION
WARNING
Before operating this equipment, make sure that all requirements of TB SIG 291 are
met. Injury or DEATH could result from improper or careless operation.
3-1. General
a. This chapter covers only items used by the
operator.
b. Mast AB-903/G is raised (or lowered) by
using a handcrank. See figure 3-1.
c. DO NOT raise the mast unless the following
procedures are taken:
(1) Antenna adapter is secured to the mast
with the stop pin (fig. 5-4).
(2) The safety (securing) pin (fig. 1-4)
has been removed from the innermost (top) section of the mast assembly.
(3) Loop of wire above the spring connected
to the toggle lock (fig. 1–4) has been removed
from the toggle lock attachment extension (fig.
5-4).
d. Be sure that the lower guy ropes are reasonably taut; allow the top guys to remain slack.
The mast should not be out of the vertical position by more than 7°. If guyed, the mast can
withstand winds of 50 miles per hour. Use of
the mast beyond these wind conditions can damage it.
3–2. Operating Instructions
a. Attach the crank handle assembly to the
square shaft extending from the winch assembly.
NOTE
The square shaft is double-ended, extending completely through the winch
assembly. Select the shaft end with the
groove and yellow circular arrow on
the winch case indicating UP or DOWN.
b. Lock the handle to the shaft with the handle
lock by sliding the retainer clip sideways to secure it.
CAUTION
Be sure the locking pin (fig. 3-1) is
loosened.
c. Pull the locking pin straight out, twist it
one-quarter turn (90°), and place it back into
position. The pin is now disengaged from the
winch assembly gears, and the crank handle may
now be rotated.
d. To raise the mast, turn the handle clockwise. To lower the mast, turn the handle counterclockwise. The yellow circular arrow indicates
direction of motion.
e. Approximately 54 turns of the crank handle
are required to fully raise ( or fully lower)
the mast.
f. To lock the mast in any position, pull the
locking pin straight out, twist it one-quarter turn
(90°), and seat it. It may be necessary to turn
the crank handle slightly so that the locking pin
drops smoothly into position to insure that the
mast is firmly locked.
g. Insure that all guy ropes are securely fastened by following the procedures given in paragraph 2–7.
3-1
TM 11-5985-263-15
Figure 3–1. Mast AB–903/G, winch assembly, crank handle attached.
3-2
TM 11-5985-263-15
Figure 3-2. Mast AB-903/G, upper section view.
3-3
TM 11-5985-263-15
CHAPTER 4
OPERATOR AND ORGANIZATIONAL MAINTENANCE
WARNING
During removal, disassembly, erection, assembly, or repair of the mast, conform to
all safety requirements of TB SIG 291. Injury or DEATH could result from failure
to comply with safe practices.
Section 1. OPERATOR’S MAINTENANCE
4-1. Scope of Operator’s Maintenance
The maintenance duties assigned to the operator
of Mast AB–903/G are listed below together with
reference to the paragraphs covering the specific
maintenance function. The duties assigned do
not require tools or test equipment other than
those listed in paragraph 4-2.
a. Daily preventive maintenance checks and
services (para 4-6).
b. Cleaning (para 4-6).
4-2. Tools and Equipment Required
Two adjustable wrenches (FSN 6120-264-3795)
and a screwdriver (FSN 5120-276-1272) are
required. The following materials are also required:
a. Soft-bristled brush.
b. Trichloroethane.
c. Lintfree cleaning cloth.
4-3. Operator’s Preventive Maintenance
Preventive maintenance is the systematic care,
servicing, and inspection of equipment to prevent the occurrence of trouble, to reduce downtime, and to assure that the equipment is serviceable.
a. Systematic Care. The procedures given cover
routine systematic care and cleaning essential
to proper upkeep of this equipment when it is
used separately. When this equipment is used
as part of a set or system, follow the procedures
established in the set or system manual.
b. Preventive Maintenance Checks and Services. The preventive maintenance checks and
services charts outline functions to be performed
at specific intervals; however, if the equipment
is used as part of a set or system, follow the
procedures established in the set or system man-
ual. For equipments operated separately, these
checks and services are to maintain Army electronic equipment in a combat-serviceable condition; that is, in good general (physical) condition and in good operating condition. To assist
operators in maintaining combat serviceability,
the chart indicates what to check, how to check,
and the normal conditions; the References
column lists the illustrations, paragraphs, or
manuals that contain detailed repair or replace
ment procedures. If the defect cannot be remedied by the operator, higher category of maintenance or repair is required. Records and reports
of these checks and services must be made in
accordance with the requirements set forth in
TM 36-750.
4-4. Operator’s Preventive Maintenance
Checks and Service Periods
a. Preventive maintenance checks and services of the AB-903/G are required daily and
weekly. The lightweight, cable-driven mast and
its associated parts require these maintenance
inspections to detect and correct damage caused
by continued exposure of the mast to the elements. The maintenance services are of the utmost importance. Failure of any one of the mast
sections or cables may cause complete failure of
the mast with resultant damage to equipment
and possible injury to personnel. Excessive dampness, salt spray, snow, ice, continuous heat, and
rapid changes in temperature may cause corrosion of the aluminum and magnesium components and blistering or peeling of the paint on the
mast and its components. High winds may cause
the guy anchors to creep in the soil and the guy
lines to slacken. In cold climates, heavy coatings
of ice or an accumulation of snow may overload
4-1
TM 11-5985-263-15
the mast and strain the guy. Also, dirt and corrosion may clog the drain holes in the base plate,
and water will accumulate in the lower mast tube
section which may cause the mast sections to
burst when the water freezes and changes to
ice.
b. Paragraph 4-5 specifies checks and services that must be accomplished daily or under
the special conditions listed below.
(1) Fixed installation.
(a) When equipment is initially installed.
(b) When equipment is reinstalled after
removal for any reason.
(c) During severe weather conditions.
(d) At least once each week if the equipment is maintained in a standby condition.
(2) Vehicular installation.
(a) Before the vehicle starts on a mission.
(b) When equipment is initially installed.
(c) When equipment is reinstalled after
removal for any reason.
(d) At least once each week if the equipment is maintained in a standby condition. -
4-5. Operator’s Daily Preventive Maintenance Checks and Services Chart
Sequence
No.
Item to be inspected
1
Mast assembly . . . . . . . . . . . . . . . . .
2
Guy lines and stakes . . . . . . . . . . . . . .
3
Mast base cap . . . . . . . . . . . . . .
4
Base drain holes (bottom of
mast).
Dust cover brackets . . . . . . . . .
5
Procdures
References
Check the general condition and completeness for carrying case, spare
parts, and mounting brackets.
Clean all exterior surfaces . . . . . . . . . .
Check guy lines and stakes to see that
they are secure. Remove any ice accumulation on guy lines.
Check area around plate for proper
drainage. If the soil is worn away,
add fill dirt and dig drainage
ditches to guide water away.
Inspect holes for water drainage . . . . .
Inspect accessible items, bolts, and
attaching screws for looseness.
4-6. Cleaning
WARNING
The fumes of trichloroethane are toxic.
Provide thorough ventilation when
used. DO NOT use near an open flame.
Trichloroethane is not flammable, but
exposure of fumes to an open flame converts the flames to highly toxic, dangerous gases.
The working parts of the mast must be kept
Para 1-6 and fig. 1-3.
Para 4-6.
Para 2-6.
Para 2-6 and fig. 2-2.
Para 4–6 and fig. 2-2.
Fig. 3-1.
clean. Remove dust and dirt with a clean cloth.
Remove grease, fungus, and ground-in dirt with
a cloth dampened (not wet) with trichloroethane. Check drainage holes at the bottom of
mast (fig. 2-2). If dirt or sand is present, remove
all loose external dirt with a dry cloth. If this
procedure does not clear the drain holes, refer
the mast to higher category of maintenance. Be
careful when cleaning holes if they are plugged
shut; severe damage to cables and pulleys may
result at the base of the mast.
Section II. ORGANIZATIONAL MAINTENANCE
4-7. Scope of Organizational Maintenance
a. This section contains instructions covering
organizational maintenance of Mast AB–903/G.
It includes instructions for performing preventive and periodic maintenance services and repair functions to be accomplished by the organizational repairman.
b. Organizational maintenance of Mast AB–
903/G includes—
4-2
(1) Tools and equipment required (para 48).
(2) Organizational preventive maintenance
(para 4-9).
(3) Monthly preventive maintenance checks
and services chart (para 4–11 ).
(4) Quarterly preventive maintenance checks
and services chart (para 4-13).
TM 11-5985-263-15
4-8. Tools and Materials Required
A list of parts authorized for organizational
maintenance appears in appendix D. The tools
and materials required for organizational maintenance are listed below.
a. Tools. Adjustable wrench (FSN 5120–264–
3795), and screwdriver ( FSN 5120–278-1272).
b. Materials.
(1) Trichloroethane.
quarterly unless otherwise directed by the commanding officer. The preventive maintenance
checks and services should be scheduled concurrently with the periodic service schedule of the
carrying vehicle for all vehicular installations.
b. Maintenance forms and records to be used
and maintained on this equipment are specified
in TM 38–750.
4-10. Organizational Monthly Maintenance
(2) Lintfree cleaning cloth.
(3) Soft-bristled brush.
Perform the maintenance functions indicated in
the monthly preventive maintenance checks and
services chart (para 4–13) once each month.
A month is defined as approximately 30 calendar
days of four operations (up and down) daily.
If the equipment is operated 8 times a day (up
and down), the monthly preventive maintenance
checks and services should be performed at 15-day
intervals. Adjustment of the maintenance interval
must be made to compensate for an unusual operating conditions. Equipment maintained in a
standby (ready for immediate operation) condition must have monthly preventive maintenance
checks and services performed on it. Equipment
in limited storage (requires service before operation) does not require monthly preventive maintenance.
c. Test Equipment. None required.
4–9. Organizational Preventive Maintenance
a. Preventive maintenance is the systematic
care, inspection, and servicing of equipment to
maintain it in serviceable condition, prevent
breakdowns, and assure maximum operational
capability. Preventive maintenance is the responsibility of all categories concerned with the equipment and includes the inspection, testing, and repair or replacement of parts, subassemblies, or
units that inspection and tests indicate would
probably fail before the next scheduled, periodic
service. Preventive maintenance checks and services of Mast AB–903/G at the organizational
maintenance category are made monthly and
4-11. Organizational Monthly Preventive Maintenance Checks and Services Chart
Sequence
No.
References
Procedure
Item to be inspected
1
Winch assembly . . . . . . . . . . . .
Check cable windings to see that they
are even and not overlapped.
Fig. 5-2.
2
Cable drive pulleys . . . . . . . . . .
Check for freedom of movement.
Check to see that shaft retaining
rings are secure and not missing.
Figs. 3-2 and 5-2.
3
Mast tube sections . . . . . . . .
Clean sliding area of tube sections
when dirt or corrosion is evident.
Para 4-6.
4
Painted surfaces . . . . . . . . . . . . . . .
Touch up scratched and chipped spots
with paint.
4-12. Organizational Quarterly Maintenance
Quarterly preventive maintenance checks and
deficiencies or shortcomings will be recorded in
accordance with the requirements of TM 38-750.
services on Mast AB–903/G are required. Periodic monthly services constitute a part of the quarterly preventive maintenance checks and ser-
Perform all the checks and services listed in
the quarterly preventive maintenance checks and
services chart (par 4–13) in the sequence listed.
vices and must be performed concurrently. All
4-13. Organizational Quarterly Preventive Maintenance Checks and Services Chart
Sequence
No.
1
2
Item to he inspected
Completeness . . . . . . . . . . . . . . .
Installation . . . . . . . . . . . . . . . . . .
Procedure
See that the equipment is complete
Check to see that equipment is properly installed.
References
App. B.
Paras. 2-3 through 2-7.
4-3
TM 11-5985-263-15
Sequence
No.
Item to be inspected
References
Procedure
See that the equipment is clean . . . .
Para 4-6.
Para 4-6.
3
4
Cleanliness . . . . . . . . . . . . .
Preservation . . . . . . . . . . . .
5
Publications . . . . . . . . . . . . . .
6
Modifications . . . . . . . . . . . . . . . . .
7
Mast operation . . . . . . . . . . . . .
Check operation of mast by raising
and lowering.
Para 3-2.
8
Winch brakes . . . . . . . . . . . . .
9
Winch assembly . . . . . . . . . . . . .
Raise mast. When stopped, mast will
remain stationary at any height.
Mast raises and lowers evenly . . . . . .
10
Cable drive pulleys . . . . . . . . . .
If in need
gory of
If in need
gory of
None.
11
Mast tube sections . . . . . . . . . .
12
Cables . . . . . . . . . . . . . . .
4-4
Check all surfaces for evidence of
fungus and corrosion.
Check to see that all publications are
complete, serviceable, and current.
Check DA Pam 310–7 to determine
if new applicable MWO’s have been
published. All URGENT MWO’s
must be applied immediately. All
NORMAL MWO’s must be scheduled.
Check for freedom of movement.
Check to see that shaft retaining
rings are secure and not missing.
Remove antenna, and lay mast on
bench or table. Extend mast and
inspect all sections for dirt, sand,
or corrosion. Clean as required.
Check cables for proper tension—
a. Unequal distances between sections of retracted mast (fig.
5-8) indicate need for adjustment and tensioning.
b. If No. 2 lift cable (in gearbox)
can be pulled out to a point
where it touches spacer bar,
tensioning is required.
DA Pam 310-4.
TM 36-750 and DA Pam 310-7.
of adjustment, higher catemaintenance is required.
of adjustment, higher catemaintenance is required.
Para 4-6.
Refer to higher category of maintenance.
TM 11-5985-263-15
CHAPTER 5
MECHANICAL FUNCTIONING OF MAST AB-903/G
5-1. General
Cables and pulleys are used to transfer energy
from a handdriven source to a mechanical load.
Knowledge of the principles used in elevating
and retracting the mast will aid maintenance
personnel in servicing the mast at the direct support, general support and depot maintenance
categories.
5–2. Description of Components
The mast consists of six mast sections: tube assembly No. 1 through tube assembly No. 6.
Tube assembly No. 1 remains fixed, while all
the other tube assemblies telescope into each
other as shown in figure 5-1.
a. Tube assembly No. 1 contains the winch assembly (fig. 5–2) with its own gears and pulleys,
winch brake, four additional pulleys used with
cables 2L and 2R, and three cable adjusters.
A view of cable adjuster 1C is shown in figure
5–3; this adjustment is at the bottom of tube
assembly No. 2 inside the base cap.
Figure 5–1. Mast AB–903/G cabling and pulley diagram.
Located in back of manual.
b. With the exception of diameter and a few
other dimensions, tube assemblies No. 2 through
5 are identical. Each assembly has two pulleys,
one of which is visible while the other is hidden
from outside view at the base of each tube assembly. Pulleys 5 and 6 are shown in figure 5-3;
with the mast retracted and the base cap removed, the pulleys are easily seen. One of these attached to tube assembly No. 2.
c. Tube assemblies Nos. 2, 3, and 4 also have
cable adjusters which must be adjusted during
the alignment procedure discussed in paragraph
7-6. These are shown in figure 5-1 as adjusters
2A, 2B, 3A, 3B, 4A, and 4B. They are also shown
in figures 3-2 and 5-4. Cable adjusters 1A, 1B,
and 3B are shown in figure 3-2, and cable adjusters 2A, 2B, 4A, and 4B are shown in figure
5-4.
d. Tube assembly No. 6 has the smallest diameter, moves the fastest, and is the section to
which the applicable antenna is attached. The
maximum antenna weight, including the mount,
which may be attached to this smallest diameter
section, is 20 pounds. Each antenna has its own
matching mount which permits the antenna to
remain attached to the mast. In the case of Antenna AS–1729/VRC, a counterpoise adaptor unit
(fig. 1–3) acts as the antenna mount. In figures
5-5 and 5-6, Matching Unit-Base MX-6707/VRC
is shown inserted in the counterpoise adaptor
unit ready for assembly. For installation and
mounting of the counterpoise adaptor unit and
Antenna AS–1729/VRC, refer to paragraphs
2–4, 2–6, 2–8, and 2–9. For information on other
antennas and mounts, refer to the applicable
technical manual.
e. The winch assembly (fig. 5-2) contains the
following items:
(1) Brake assembly, consisting of brakeshoe, brakeshoe mounting frame, and one-way
clutch. The clutch is fixed to the crank handle
shaft.
(2) The cable drum to which cables 2L and
2R are attached.
(3) An idler shaft which has a small gear
at one end connected to the cable drum, and a
large gear at the other end connected to the crank
handle shaft. The large gear has holes drilled in
it to accept the locking pin.
(4) The locking pin is used to prevent motion of the mast when the mast is handcranked
to the correct height. The locking pin fits into
any of several holes in the larger idler gear.
f. The crank handle (fig. 3-1) fits onto the
end of the crank handle shaft. The handle lock
must be closed to secure the handle to the brake
assembly during operation. The locking pin is
loosened by pulling it straight out, twisting it
90°, and resetting it in the raised position.
g. Other features of the mast are as follows:
(1) When the mast is fully extended, the
5-1
TM 11-5985-263-15
Figure 5-2. Mast AB–903/G, winch assembly, mounted on tube assembly No. 1.
stop pin (fig. 5–4 ) prevents the mast from moving beyond its maximum limit.
(2) The drainage holes in the base of the
mast (fig. 2–2 ), must be clear at all times to prevent accumulation of water in tube assembly No.
1 with resultant corrosion and damage. If accumulated water freezes, expanding pressure can
damage the mast.
(3) Three vertical holes at the lower end
of tube assembly No. 2 indicate maximum height.
5-3. Brake Assembly
The brake assembly includes a one-directional
clutch and brakeshoe to prevent lowering of the
mast by its own weight and the weight of the
5-2
antenna. The one-directional clutch permits free
operation during erection of the mast and is engaged when holding or lowering the mast. The
brakeshoe is spring-loaded to compensate for
wear.
5-4. Cable Assemblies
The upward motion of the mast is described below.
a. As viewed from the handcrank side of the
winch assembly, turning the handcrank in the
clockwise direction causes the cable drum to pull
cable 2L around the drum, and allows cable 2R
to pay out slack cable and raise tube assembly
No. 2.
TM 11-5985-263-15
Figure 5-3. Mast AB-903/G, cable adjuster 1C, bottom of tube assembly No. 1 base
cap removed.
5-3
TM 11-5985-263-15
Figure 5-4. Mast AB-903/G, winch assembly side view, dust covers removed.
b. As tube assembly No. 2 rises, tension is
applied to cable 3L and causes tube assembly
No. 3 to rise.
c. As a result of the motion of tube assembly
No. 3, tension is exerted on cable 4L, causing
tube assembly No. 4 to rise in a similar way.
d. The sequence continues. Tube assembly No. 4
causes tube assembly No. 5 to rise because of
tension on cable 5L, and tube assembly No. 5
causes tube assembly No. 6 to move as a result
of tension on cable 6L.
e. Approximately 54-66 turns of the crank
handle are needed to fully erect the mast. When
the mast has reached its full height, the stop
pin (fig. 5-4) contacts the outer ring at the base
of tube assembly No. 2, stopping tube assembly
No. 2. This, in turn, stops all other mast sections
5-4
since they cannot move if tube assembly No. 2 has
been halted.
f. At times, it may not be necessary to raise the
mast to its full height; when the desired height
is selected, the locking pin (fig. 3-1) is placed
into position. It may be necessary to rotate the
crank handle slightly so that the locking pin
drops firmly into one of the holes on the larger
idler gear.
g. Turning the handcrank in a counterclockwise direction reverses the sequence described
in above.
5-5. Counterpoise Adaptor Unit
On Mast AB-903/G procured on order FR 28043-J5-00736(E) and contract DAAB05-670173, items furnished were a counterpoise adap-
TM 11-5985-263-15
Figure 5-5. Counterpoise adapter unit and disassembled Antenna AS-1729/VRC.
tor unit and four counterpoise tubes (figs. 5-5
and 5-7). The counterpoise assembly, together
with the associated Antenna AS-1729/VRC, comprima a ground-plane antenna. The whip portion
of the AS-1729/VRC acts as the radiating element, with the counterpoise assembly as an artificial ground.
5-5
TM 11-5985-263-15
Figure 5-6. Counterpoise adaptor unit and Matching Unit-Base MX-6707/VRC.
5-6
TM 11-5985-263-15
Figure 5-7. Counterpoise assembly tubes, clip ends.
5-7
TM 11-5985-263-15
Figure 5-8. Tensioning gage for lift cable 2L.
5-8
TM 11-5985-263-15
Figure 5-9. Cable installation on adjusters.
5-9
TM 11-5985-263-15
CHAPTER 6
DIRECT SUPPORT MAINTENANCE
Section I. MAINTENANCE INSTRUCTIONS
6-1. General
6-4 Adjustment of Winch Brake
The direct support maintenance procedures outlined in this chapter supplement the procedures
described for organizational maintenance. The
systematic troubleshooting procedure, which begins with the operational and sectionalization
checks that can be performed at the organizational maintenance category, is carried to a higher category of maintenance in this section. Adjustment of the winch brake (para 6-4 and fig.
5-2) and adjustment of the cable tension (para
6-5) are covered in this chapter.
CAUTION
The mast must be vertical and secure
to insure satisfactory adjustment of the
winch brake with antenna installed. An
equivalent weight of 20 pounds may be
used in place of the antenna.
a. Raise the mast to approximately halfway
position (15 feet) using the handcrank.
b. Remove the eight dust cover screws (fig.
3-1) which hold the dust cover over the winch
assembly.
c. While holding the crank handle, loosen the
check nut adjustment (fig. 5-2) which secures
the screw that holds the winch brake against
the winch drum.
CAUTION
Do not overtighten; damage to components may result.
d. Tighten the setscrew until the winch brake
will hold the mast and antenna load at any position without pressure being applied to the crank
handle to prevent motion of the mast sections.
Tighten the check nut adjustment to secure the
setscrew.
e. Replace the dust cover by securing the
eight dust cover screws (fig. 3-1).
f. Retract the mast. The mast should hold when
stopped at any position.
6-2. Tools and Equipment Required
The authorized tools and test equipment are listed
in appendix C.
6-3. Organization of Troubleshooting
Procedures
a. The first step in servicing Mast AB–903/G,
or any of its associated components, is to sectionalize the fault to one of the mast sections
listed in b below. The second step is to localize
the fault to a defective part responsible for the
abnormal condition. Some faults, such as worn,
frayed, or broken cables, or dented or cracked
mast sections, can often be located by sight,
hearing, or feeling.
b. Sectionalization in Mast AB–903/G involves
the major components listed below:
(1) Winch assembly (fig. 5-2).
(2) Any of the six individual mast sections
(figs. 7-2, 7-3, and 7-6).
(3) Any of the cable assemblies 2 through
6.
(4) Components shown in figures 2-2, 1-3,
and 1–4.
c. Components listed in b (1) through (3)
above, which must be repaired or replaced, must
be referred to a higher category of maintenance;
however, adjustment of cables 2 through 6 is
authorized at direct support maintenance.
6-5. Adjustment of Cable Tension
(figs. 5-1, 5-8, and 5-9)
a. General. Adjustment of cable tension is required when distances between mast sections of
a retracted mast are unequal, or if lift cable 2L
in the gearbox can be pulled out to a point where
it touches the spacer bar. Tensioning procedures
(b below) can only be performed on cables that
have been used or prestretched as described in
paragraph 7–7. Remove the base capscrews from
the base cap at the bottom of the mast to allow
removal of the base cap and provide access to
the locknut (fig. 6-3) if required.
6-1
TM 11-5985-263-15
b. Tensioning. After it has been determined
that tensioning is required (a above), retract
the mast and place it in a vertical position and
adjust tension as described below.
(1) Tension retract cable 2R by turning
cable adjuster 1C until cable contacts winch sideplate spacer bar when 25 or 30 pounds of force
are applied to lift cable 2L.
(2) Tension lift cable 3L by turning cable
adjuster 1A until No. 3 upper housing and No. 2
upper housing separate 1/32 inch.
(3) Tension retract cable 3R by turning adjuster 1B until the two upper housings contact.
(4) Tension lift cable 4L by turning cable
adjuster 2B until No. 4 upper housing and No. 3
upper housing separate 1/32 inch.
(5) Tension retract cable 4R by turning
cable adjuster 2A until No. 3 and No. 4 upper
housings contact.
(6) Tension lift cable 5L by adjusting cable
adjuster 3B until No. 5 upper housing and No. 4
upper housing separate 1/32 inch.
(7) Tension retract cable 5R by adjusting
cable adjuster 3B until No. 4 and No. 5 upper
housings retract.
(8) Tension lift cable 6L by adjusting cable
adjuster 4B until No. 6 upper collar and No. 5
upper housing separate 1/32 inch.
(9) Tension retract cable 6R by adjusting
cable adjuster 4A until No. 6 upper collar and No.
5 upper housing contact.
(10) Cycle mast five times with a 15- to 20pound load installed on the mast. Remove load.
(11) Check tension of cable 2L with mast
retracted. If required, retension as described in
(1) above.
(12) Inspect upper housings with mast re-
tracted and determine if housings are all in contact with each other. Retensioning may be required by repeating procedures given in (1)
through (11) above.
6-6. Replacement of Base Cap
(figs. 5-3 and 2-2)
CAUTION
It is extremely important that the base
cap be replaced in the manner described
below. Failure to follow the procedures
exactly as stated with result in one of
the drainage holes being plugged shut
by the hardware inside the base of tube
assembly No. 1 which supports pulley 5.
a. Carefully examine the base cap and note the
position of the drainage holes. If necessary, draw
a light pencil line between the holes (which will
also pass through the square hole).
b. Examine the bottom of tube assembly No. 1
and note the alignment of cable adjuster 1C (fig.
5-3). When the cap is replaced, the line through
the drainage holes should be parallel with the
shaft of cable adjuster 1C.
c. Place the cap on the bottom of the mast.
Be sure that both drainage holes are cleared.
If necessary, clean the drainage holes before securing the base cap to the mast.
d. If one of the drainage holes is blocked by
the hardware that holds pulley 5, rotate the
cap 90° (one-quarter turn) in either direction.
This action will clear both drainage holes and
the cap is ready to be fastened to the bottom of
tube assembly No. 1.
e. Tighten the four base cap screws (fig. 2-2)
so that the base cap is secure against the bottom
of the mast.
Section II. TESTING PROCEDURES
6-7. General
Direct support testing procedures are required on
Mast AB–903/G. The tests described in this section determine the adequacy of the repair procedures, if any, that were performed in paragraph
6-3 through 6-6, and also those maintenance procedures performed at the operator and organizational maintenance level. If the equipment meets
the criteria stated in this section, it is considered
adequate for return to the using organization. If
the equipment fails to meet the minimum standards stated in these testing procedures, higher
category of maintenance is required.
6-2
6-8. Physical Test and Inspection
a. Tools Requred.
(1) Authorized tools are listed in appendix
C.
(2) No special materials are required.
b. Test Conditions.
(1) There must be enough area to expand the
mast to its full 30-foot length. In most tests, this
may be done with the mast lying in the horizontal position; however, a few of these tests require
that the mast be erected vertically.
(2) To determine if the mast may be tested
TM 11-5985-263-15
in a horizontal position, or if it must be tested in
a vertical position, follow the procedures stated
in the Equipment under test column (c below).
For tests performed in the vertical position, an
antenna, or equivalent weight, should be attached
to the top of the mast.
6-3
TM 11-5985-263-15
6-4
TM 11-5985-263-15
6-5
TM 11-5985-263-15
6-6
TM 11-5985-263-15
CHAPTER 7
GENERAL SUPPORT MAINTENANCE
7-1. General
The general support maintenance, repair, and
testing procedures given in this chapter supplement the repair and testing procedures used at
operator, organization, and direct support maintenance. General support maintenance includes
disassembly and reassembly of Mast AB-903/G
(including six mast sections (tube assemblies Nos.
1 through 6 and all cables), and complete disassembly and reassembly of winch assembly unit.
CAUTION
Be careful when installing old cables because of limited length.
7-2. Tools Required
The tools authorized for general support maintenance are listed in appendix C.
7-3. Disassembly of Mast AB-903/G
(fig. 5-1)
a. General. Mast AB–903/G is raised and lowered by cables as described in paragraphs 5-2,
5-3, and 5-4. Failure of any one of the cables will
prevent the mast from being raised. Replacement
of any one of the cables requires disassembly of
the winch assembly, and sometimes one or more
of the pulleys and may also require disassembly
of tube assemblies Nos. 1 through 6 depending
on the location of the cable to be replaced. Disassembly of the mast begins with tube assembly
No. 1 and continues through No. 6. Reassembly
is performed in reverse order. Since these parts
may have to be removed when replacing a cable,
all cables should be inspected for possible replacement when a broken or worn cable is found to be
the source of trouble. Look for signs of fraying
cables, particularly on the ends; inspect the cable adjuster to be sure that the cable is securely
fastened to the adjuster. After the mast has been
thoroughly disassembled, inspect each individual
tube assembly to determine if there are cracks or
dents around the outside diameter and at the base
of each assembly. Be sure that each tube assembly will slide easily into its adjoining assembly,
and that the grooved keys on each assembly are
not chipped or cracked; this is especially true for
tube assembly No. 6 which has the smallest diameter and which supports the antenna used with
the mast.
b. Initial Procedures.
(1) Remove the tension in all cables (para
6-5a).
(2) Remove the crank handle, if applicable.
(3) Insure that the locking pin (fig. 3-1) is
disengaged from the large idler gear (fig. 5-2).
(4) Insure that the stop pin and the toggle
lock are released at the top of the mast.
(5) Remove the dust cover on the winch assembly by removing the eight screws (fig. 3–1).
c. Disassembly of Winch Assembly.
(1) Remove the two snapsprings (fig. 7-1)
on either end of the brake assembly.
(2) Remove both nuts from either end of the
cable drum assembly.
(3) Remove the screws that secure the dust
cover mounting frames to both sideplates of the
winch assembly. Remove the dust cover mounting
frames.
(4) Remove the three sideplate bolts that secure the sideplate to the winch assembly (crank
handle side). Remove the sideplate. Remove the
snaprings from the gear shafts. The brake assembly, the idler gears, and the cable drum assembly
can now be removed.
(5) The ends of cables 2L and 2R are held
to the cable drum assembly by their own cable
attachment lock. To loosen the cable from the
drum, remove the screws that hold the attachment
lock to the drum; then, remove the lock. The end
of the cable will be free and can be unwrapped
from around the drum.
(6) The locking pin remains attached to the
sideplate. To remove it from the sideplate, loosen
the two nuts and screws that hold it to the sideplate; the pin can now be removed.
(7) Separate the gear from the drum by removing the two screws and tapping lightly to separate the three spring pins.
(8) To remove the winch brake, loosen the
check nut adjustment and remove the nut. With
7-1
TM 11-5985-263-15
Figure 7–1. Winch assembly components prior to disassembly.
a small screwdriver, turn the screw that holds the
winch brake to the winch brake mounting frame
until the winch brake is worked loose from the
mounting frame. Remove the winch brake.
d. Removal of Base Cap (figs. 5-3 and 5-4).
To remove the base cap, follow the procedures
given in paragraph 6-5.
e. Disassembly of Tube Assemblies.
(1) Remove the stop pin (fig. 5-4).
(2) Disconnect all four cables at upper end
as follows:
(a) To loosen cables (6L and 6R), remove
the two nuts on the opposite side of cable adjusters 4A and 4B.
(b) To loosen cables (5L and 5R), remove
the two nuts on the opposite side of cable adjusters 3A and 3B (fig. 3-2).
(c) To loosen cables (4L and 4R), remove
7-2
the two nuts on the opposite side of cable adjusters
2A and 2B (fig. .5-4).
(d) To loosen cables (3L and 3R), remove
the two nuts on the opposite side of cable adjusters 1A and 1B (fig. 3-2).
(e) Loosen the locknut (fig. 5-3) on the
opposite side of cable adjuster 1C.
(f) Turn all cable adjusters ((a) through
(e) above) until tension is removed from the cables; then, pull all cables through the cable adjusters until they are free.
CAUTION
Do not attempt to pull apart the individual mast sections at this time. Each
section has a large ring on its bottom
(inside) end which will prevent the mast
sections from coming apart until the following procedure is performed.
TM 11-5985-263-15
Figure 7-2. Tube assemblies Nos. 3, 4, and 5, bottom view.
(3) Remove the four screws from the guide
ring (figs. 7-2 and 7-3) on the top of tube assembly No. 5.
(4) Manually slide tube assembly No. 6 (fig.
7-4) from tube assembly No. 5 (fig. 7-3). Be
sure that cables 6L and 6R are completely removed.
NOTE
Tube assembly No. 6 is the only tube assembly which has no pulley at its base.
(5) Remove the four screws from the guide
ring (fig. 7-3 ) on the top of each of the other
tube assemblies (Nos. 4, 3, 2, and 1). As each
guide plate is removed, separate the smaller diameter tube from its larger diameter counterpart.
When these tubes are disassembled, cables 5, 4,
and 3 should be free of the tubes, and pulleys 12,
10 and 8 (fig. 7-2) should be visible and ready
for access or replacement, if required.
(6) To separate tube assembly No. 2 from
tube assembly No. 1, first check to see that the
cable is free from cable adjuster 1C (fig. 5-3).
Then check to see that cables 2L and 2R are free
from the cable drum assembly (fig. 7-1 ); cable
2L and 2R attachment locks should be free. Finally, check to see that the winch assembly is disassembled as described in c above and the guide
plate is free.
(7) Slowly separate the two tube assemblies.
It may be necessary to remove each cable separately. When separating the sections, cable 2R
will leave the drum first, then cable 2L. Be sure
that the cables do not wrap around the components inside the winch assembly.
(8) If difficulty is encountered in removing
the cables from any of the individual tube assemblies because of cable snagging around a pulley,
it may be necessary to remove the pulley. To remove a pulley, remove the snaprings that secure
7-3
TM 11-5985-263-15
Figure 7-3. Tube assemblies Nos. 3, 4, and 5, top view.
the pulley shaft on either end and slide the shaft
out; the pulley may then be lifted free. Pulleys
at the base of each tube assembly may be removed
only when the tube is separated from its counterpart.
f. Disassembly of Minor Components.
(1) To remove the ring assembly (figs. 7-2
and 7-3) inside of tube assembly No. 1, loosen
the four ring fastening screws around the outside of the bottom end of tube assembly No. 1.
Invert the tube, and gently shake it until the ring
assembly falls out.
(2) To remove the cable loops (fig. 7-5 ) from
the end of tube assemblies Nos. 3 through 6, the
cable loop retaining shaft must be removed (fig.
7-4). Open the snapring and remove the shaft;
the cable loop will slide off easily.
7-4
NOTE
Cable loops are held in shape by cable
clamps, (fig. 7-5). If the cable clamp
is broken, or appears worn, discard the
entire cable and replace it with a new
one (para 7-4).
(3) To remove any pulley, open the snapring
on the pulley shaft and remove the shaft and pulley.
NOTE
The guide rings on tube assemblies Nos.
2 though 6 and the lower guy plate on
tube assembly No. 1 cannot be removed;
these items are factory sealed. If these
items are defective, the entire tube assembly must be replaced.
TM 11-5985-263-15
Figure 7-4. Tube assembly No. 6, bottom view.
7-4. Reassembly of Mast AB-903/G
(fig. 5-1)
a. General. Reassembly procedures for the cables, pulleys, ring assembly, tube assemblies, and
winch assembly are given below. Of these items,
cable replacement is the most critical. The cables
must show no signs of wear or fraying; if there
is the slightest doubt as to the condition of the
cable, replace the cable. Cables 3 through 6 must
not be less than 80 inches in length, cable 2L not
less than 140 inches long, and cable 2R not less
than 128 inches long. This is to insure that sufficient cable length is available on the end to be
soldered (fig. 7-5) to allow at least one turn of
wraparound over the cable adjuster before tension is applied to any of the cables. The extra
length, if any, is NOT cut off until all adjustments
have been completed. When cables have been cut
to correct length, tin the ends of the cable with
solder to prevent fraying.
b. Initial procedures. (fig. 7-6).
(1) Insure that all guide rings are on tube
assemblies Nos. 2 through 6, and that the upper
guy plate is placed over tube assembly No. 6 before reassembly.
(2) Insure that all pulleys are in place, and
not chipped or broken. Inspect the pulley shafts;
be sure that the snaprings are on both ends.
(3) Inspect the stop pinhole (fig. 7-7). Check
for frayed or worn threads. The pin must be removed before reassembly.
(4) If cables must be replaced, be sure the
length of each cable meets the minimum length
stated in a above.
(5) Inspect all tube assemblies; cracks or
dents should not be evident. Inspect the keyway;
a typical keyway is shown in figure 7-8. The
run of the keyway must be straight and show no
signs of stress or uneveness. There must be no
dirt, paint, or lubricant along the surface of each
tube assembly where the outer surface of the
tube rides against the inner surface of the next
largest tube.
(6) Examine the winch assembly (figs. 7-1
and 5-2). All gears with teeth must show no
teeth missing, chipped, or broken. The cable drum
must be intact.
c. Reassembly Procedures.
(1) Attach cables 6L and 6R to the bottom
of tube assembly No. 6 (fig. 5-1).
(2) Attach cables 5L and 5R to the bottom
of tube assembly No. 6 (fig. 5-1).
7-5
TM 11-5985-263-15
Figure 7-5. Cables 2 through 6, cable fabrication.
(3) Attach cables 4L and 4R to the bottom
of tube assembly No. 4.
(4) Attach cables 3L and 3R to the bottom
of tube assembly No. 3.
(5) Attach cables 2L and 2R (single length
of each) to the bottom of tube assembly No. 2
(fig. 7-9). Tape cable 2L to tube assembly No. 2
during most of the remaining assembly procedures.
(6) Thread the cable through tube assemblies No. 1 through 5 as follows:
(a) Run a stiff wire (or an extra cable)
at least 6 feet long up through the hole in the
bottom of the tube assembly.
(b) Tape the cable to the stiff wire. Pull
the soldered end (fig. 7-5) through the hole, laying the tubes end to end as shown in figure 7-8.
7-6
Tape the second length (cable 6, 5, 4, or 3) to
the side of the tube assembly.
(7) Join the tube assemblies as shown in figure 7-8. Start assembly with smallest diameter
tube assembly. Insure that the guide key fits evenly into the keyway. It may be necessary to raise
the rear end of the smallest diameter tube assembly so that it slides easily into the larger diameter tube assembly.
(8) As the tube assemblies are connected,
thread the lift (up) cables through the hole in
the outermost (larger diameter tube), and the
lowering (down) cables over the pulleys.
(9) As the tube assemblies are telescoped
together, pull the slack out of the cables. Thread
the end to be soldered through the cable adjuster
for that cable as shown in figure 5-9.
TM 11-5985-263-15
Figure 7-6. Tube assemblies Nos. 1 through 6.
(10) Slowly turn the cable adjuster clockwise, using the tool required (para 6-2). Balance each pair of tubes as they are fully contraced together.
(11) Tighten up the cable adjusters just
enough to take up the slack. Do NOT attempt to
make cable tension adjustments at this time.
(12) Refer to figure 5-1, and thread cable 2L from the bottom of tube assembly No. 2
through the hole in the side of tube assembly No.
1 and over pulleys 4 and 3. Pull the cable through
the hole until the slack is taken up. Then, pull
the cable over pulley 1.
(13) Thread cable 2R through the hole in
the side of tube assembly No. 1 and over pulleys
1 and 2 as shown in figure 5-1.
NOTE
Before performing the procedures given
in (14) (15) and (16) below, tube assembly No. 2 must be fully inserted into tube assembly No. 1.
(14) Wind cable 2L two turns on the large
idler gear side (fig. 5-2) of the cable drum assembly (fig. 7-1).
(15) Run the excess cable down through the
hole in the cable drum. Replace the cable 2L attachment lock (fig. 5-2) on the cable drum as.
sembly with the screws required to secure the
cable.
(16) Wind cable 2R around the cable drum
assembly around the remaining run on the drum
toward the crank handle side of the drum. Run
the excess cable down through the hole on the
drum, and replace the cable 2R attachment lock
(not shown) into the slot on the large-toothed
gear (fig. 5-2) with the two screws required.
NOTE
Tape the cable windings to the drum
during the remainder of the assembly
to prevent the cables from loosening.
If necessary, the cable turns may be
flattened with a rubber mallet while
on the cable drum assembly before the
retainer is tightened.
(17) Align the cable drum assembly so that
the secured end of cable 2L enters at the top of
the drum with the required two turns as stated
in (14) above. This alignment is shown in figure
5-2.
7-7
TM 11-5985-263-15
Figure 7-7. Tube assemblies Nos. 1 and 2.
7–5. Reassembly of Winch Assembly
Reassemble the winch assembly as follows:
a. If the large idler gear (fig. 5-2) has been
removed from the cable drum assembly, replace
it with the two screws and three spring pins.
b. If the winch brake has been removed, replace it. Engagement should not take place at
this time. Final adjustment of winch brake should
be performed on completion of final assembly.
CAUTION
Do not overtighten screws. Damage to
the components may result.
c. If the locking pin has been removed, fasten
it to the sideplate with the two nuts and screws.
Tighten the screws; be sure that the locking pin
is free to move in and out through the hole in the
sideplate.
d. Reassemble the cable drum assembly, idler
gears, and brake assembly as shown in figures
5-2 and 7-1. It may be necessary to turn the gears
7-8
slightly until they fit evenly into position. Do
NOT force the gears into place; when they are
meshed together, they will fit evenly and rotate
smoothly. Replace the snaprings on the gear
shafts on both sideplates.
CAUTION
Do not overtighten bolts. Damage to
components may result.
e. Replace and tighten the three sideplate bolts
that were removed in paragraph 7-3 c (4) from
the crank handle side. Be sure that all gears and
parts fit smoothly before final tightening of
hardware.
CAUTION
Do not overtighten nuts. Damage to
components may result.
f. Replace and tighten the nuts (fig. 7-1) on
both sides of the cable drum assembly. Be sure
that all snaprings are in place on all gears, but
do not replace the dust cover at this time.
TM 11-5985-263-15
Figure 7-8. Tube assemblies Nos. 3 and 4 ready for assembly.
7-6. Final Adjustment Procedures
After the procedure given in paragraph 7-5 f is
completed, nearly all the slack in cables 2L and
2R should be removed; that is, cable runs around the cable drum are straight and some tightness of the cables is evident. The mast must be
fully contracted during the following steps. Remember that the tightening of one cable will also
tighten the other cable since they are effectively one continuous cable.
a. Insert cable 2R into the hole in cable adjuster
1C (fig. 5-3).
b. Equalize the tension in both cables by pulling on cable 2L while performing the adjustment
in c below.
c. Loosen the locknut on the right-hand side
of cable adjuster 1C (fig. 5-3) ; then, with a 3/8inch wrench (FSN 5120-449-8199), tighten ca-
ble adjuster 1C until all the slack is removed
from cable 2L. Hook spring scale, etc. Then
tighten the locknut.
d. After cables 2L and 2R are tightened, cables 6, 5, 4, and 3 must be tightened. Loosen all
locknuts on the opposite sides of cable adjusters
1A, 1B, 2A, 2B, 3A, 3B, 4A, and 4B (figs. 2-4
and 2-5).
7–7. Prestretch Cables
a. Retain mast in retracted position.
b. Tension retract cable 2R until 25 to 30
pounds of force on lift cable 2L cause cable to
contact winch sideplate spacer bar.
c. Exert 100 inch-pound torque on retract cable 3R tensioner and lock.
d. Repeat c above for retract cable 4R tensioner and lock.
7-9
TM 11-5985-263-15
Figure 7-9. Tube assembly No. 2, bottom view.
e. Exert 75 inch-pound torque on retract cable
4R tensioner and lock.
f. Repeat e above for lift cable 4L.
g. Exert 50 inch-pound torque on retract cable 5R tensioner and lock.
h. Repeat g above for lift cable 5L.
i. Exert 50 inch-pound torque on retract cable
6R tensioner and lock.
j. Repeat i above for lift cable 6L.
k. Retain tension for 10 minutes; then, remove tension, leaving cables slack in following
order: 6L, 6R, 5L, 5R, 4L, 4R, 3L, and 3R. Retain
tension on cables 2L and 2R.
l. Tension cables as described in paragraph
6-5.
7-10
m. After all cables have been tensioned, cut
the excess cable from the ends and solder the
ends.
n. Replace the base cap on the bottom of tube
assembly No. 1.
o. Install the dust covers.
p. Insure the drainage holes on the base cap
are clear and clean. Be sure that the spring, the
toggle lock, and the safety pin are attached to
tube assembly No. 1.
q. After the mast is completely assembled,
check to see that it raises and lowers evenly.
7–8. Final Testing Procedures
Final testing procedures for Mast AB–903/G con-
TM 11-5985-263-15
sist of testing the operation and condition of the
mast. These test procedures are identical with
direct support testing procedures given in paragraphs 6-7 and 6-8. Equipment meeting the cri-
teria of these tests is suitable for return to the
user. Those equipments which fail to meet the
performance standard must be forwarded to depot maintenance for overhaul and rebuilding.
7-11
TM 11-5885-263-15
CHAPTER 8
DEPOT MAINTENANCE
8-1. General
8-2. Tools and Materials Required
Depot maintenance of the AB-903/G consists of
overhaul or rebuild of any individual mast components or the entire mast. Final tests for the rebuilt
mast are the same as for direct support maintenance (paras 6-7 and 6-8). The parts available for
depot maintenance of the mast are listed in TM
11-5985-263-34P.
The tools and materials required for depot maintenance are the same as those listed for general
support maintenance. Also, any depot maintenance shop facility can be used for the required
maintenance.
Change 2
8-1/8-2 blank
TM 11-5985-263-15
CHAPTER 9
SHIPMENT, LIMITED STORAGE, AND DEMOLITION
TO PREVENT ENEMY USE
Section I. SHIPMENT AND LIMITED STORAGE
9-1. Disassembly of Equipment
WARNING
Disconnect all radio equipment from
the radio-frequency (rf) transmission
line and the antenna assembly before
performing any disassembly.
a. Prepare a clean, dry surface for stacking
the components, preferably one above the ground
or floor.
b. Carefully loosen the upper guy ropes, as
necessary, making use of any necessary manpower to insure that the mast is under full control
at all times.
c. Prepare for lowering the mast by locking
the crank handle to the shaft with the handle
lock. To do this, slide the retainer clip sideways.
d. Release the locking pin (fig. 3-1.) by lifting the pin straight back, twisting it one-quarter
turn (90°) to the lockout position, and resetting
it in the released position.
e. To lower the mast; crank the handle counterclockwise (DOWN) (fig. 3-1). Approximately
54 turns of the crank handle are required to fully
lower the mast.
CAUTION
Be careful when handling counterpoise tubes and sharp antenna elements
to prevent possible serious physical injury.
f. Remove the entire counterpoise assembly
for Antenna AS-1729/VRC from the mast.
NOTE
If an antenna other than Antenna AS1729/VRC is being used, refer to the
applicable technical manual for further
information.
g. Disconnect Cables CX-4722/VRC and CG1773/U from Matching Unit-Base MX-6707/
VRC. Remove Antenna Element AS-1730VRC
from Matching Unit-Base MX-6707/VRC; then
separate Antenna Elements AS-1738/VRC and
AT-1095/VRC.
h. Remove the counterpoise wire from the one
tube which has a double clip on one end. Refer
to figure 2-3. Remove the wire from the other
three single-clip tubes. Remove the counterpoise
spool from the canvas accessory bag and wrap
the counterpoise wire around it. Store the counterpoise wire and spool (figs. 1-3 and 1-4) in
the accessory bag.
i. Remove the counterpoise elements by loosening the securing screws (fig. 2-3). Fasten the
three elements (without the rubber gaskets) to
the element with the rubber gaskets by pressing
the elements into the slots on the gaskets.
j. Remove Matching Unit-Base MX-6707/VRC
from the counterpoise adaptor unit by loosening
the four screws with an adjustable wrench. Package Matching Unit-Base MX-6707/VRC and Antenna Elements AS-1730/VRC and AT-1095/
VRC in a fiberboard box.
NOTE
Complete packaging instructions for
Antenna AS-1729/VRC are given in
TM 11-5820-401-20.
k. Unhook the three upper guy wire assemblies on the mast from the upper guy attachment
plate (fig. 1-1 ). Roll them up, and store them
in the accessory bag.
l. Use any necessary manpower to hold the
mast erect; then, unhook the three lower guy
wire assemblies from the lower guy attachment
plate, roll them up, and store them in the accessory bag.
m. If the crank handle is attached to the mast,
remove the handle by loosening the handle lock
(fig. 3-1). Stow the handle in the canvas accessory bag.
n. Lift the mast off the base plate, and carefully lay it down on a clean, dry surface (a above)
Insure that the mast is fully collapsed.
o. Insert the four counterpoise tubes into the
uppermost (innermost) mast section, if applicable. Slide them in carefully so that the rubber
gasket does not tear or jam inside the mast. Slide
9-1
TM 11-5985-263-15
them in far enough so that the protective cap
is placed on the end of the mast.
NOTE
If no counterpoise tubes are furnished
with the mast, place the protective cap
over the end of the mast.
p. Place the loop of wire closest to the spring
(fig. 1-3) over the toggle-lock attachment extension (fig. 1-4). Secure the toggle-lock in the
downward position.
q. Position the protective cap (fig. 1-3) so that
it is lined up with the hole for inserting the securing pin (fig. 1-4) ; then, insert the securing
pin into the hole. Pull slightly on the protective
cap to insure that the end of the mast is sealed.
r. Place all accessory items into the canvas accessory bag. Secure the webbing straps on the
front of the case.
9-2. Repackaging for Shipment
or Limited Storage
The exact procedure for repackaging depends on
the material available and the conditions under
which the equipment is to be shipped or stored.
If available, use as much of the original pack-
ing material as possible. The following procedure
outlines general packaging methods:
a. Insure that all accessories, including the
technical manual, are in the accessory bag. Be
sure that Mast AB–903/G is secured with the
securing pin and the toggle-lock mechanism.
b. Cushion all surfaces of the accessory bag
with paperboard or fiberboard cushioning wrapping material. Cushion Mast AB–903/G in a similar manner.
c. Secure the cushioning around the mast with
gummed paper tape. Perform a similar operation
with the accessory bag.
d. Place the accessory bag into a fiberboard
box, and secure with water-resistant, pressuresensitive tape.
e. Place Mast AB–903/G into a fiberboard box.
Secure with water-resistant, pressure-sensitive
tape.
f. Place both secured boxes into a wooden box.
Nail down the box lid, and strap the nailed wooden box with flat steel strapping.
NOTE
Refer to SB 38–100 for Federal stock
numbers of materials.
Section lI. DEMOLITION OF MATERIEL TO PREVENT ENEMY USE
9–3. Authority for Demolition
a. The demolition procedures given in paragraph 9-4 will be used to prevent the enemy from
using or salvaging this equipment. Demolition
of the equipment will be accomplished only upon
the order of the commander.
b. Thorough demolition of equipment will be
accomplished through the use of procedures outlined in International Standardization Agreement—STANAG 2113, Destruction of Military
Technical Equipment. Methods of destruction
should achieve such damage to equipment and essential spare parts that it will not be possible to
restore the equipment to a usable condition in the
combat zone either by repair or cannibalization.
The reporting of the destruction of equipment
is to be done through command channels.
c. If a destruction plan is not provided by higher authority, one should be prepared by the organization using the equipment. In this plan,
personnel should be assigned specific destruction
tasks, but all personnel in the using organization
should be familiar with all aspects of the complete destruction plan. The plan must be adequate
and easily carried out in the field and must provide for as complete a destruction as available
9-2
time, equipment, and personnel will permit.
Because the time required for complete destruction may not always be available, the destruction
plan must establish priorities so that essential
parts of the equipments will be destroyed in the
order of their importance. Systematic destruction
of the same important units of equipment of a
given type will prevent the enemy from learning
the important features of the equipment or assembling a complete equipment by cannibalization of partially destroyed equipment. Adequate
destruction of some units of equipment should
always be accomplished rather than partial destruction of all units. Which of the methods listed
in paragraph 6-4 is to be used depends on the
time available for destruction.
9-4. Methods of Destruction
a. Destruction Priority. STANAG 2113 outlines the general priorities for any equipment
which is to be destroyed. These priorities, as applied to Mast AB-903/G are listed below.
(1) Cables on all mast sections.
(2) Winch assembly.
(3) All sliding mast sections.
(4) All accessory items.
TM 11-5985-263-15
b. Smash. Smash the gearbox, antenna, and
other interior parts; use sledges, hammers, axes,
crowbars, or other heavy tools.
c. Cut. Cut the cords and cables; use axes, handaxes, or machetes.
d. Burn. Burn the cords, and manuals; use
gasoline, kerosene, oil, flamethrowers, or incendiary grenades.
e. Bend. Bend the panels, casing, connectors,
and mast sections.
WARNING
Be extremely careful with explosive and
incendiary devices. Use these items only
when the need is urgent.
f. Explosives. If explosives are necessary, use
firearms, grenades, or TNT.
g. Disposal. Burn or scatter the destroyed parts
in slit trenches, foxholes, or other holes, or throw
them into nearby streams.
9-3
TM 11-5985-263-15
APPENDIX A
REFERENCES
Following is a list of applicable manuals that are available to personnel concerned with Mast AB-903/G.
DA Pam 310-4 . . . . . . . . . . . . . . Index of Technical Manuals, Technical Bulletins, Supply Manuals (types 7,
8, and 9), Supply Bulletins, and Lubrication Orders.
DA Pam 310-7 . . . . . . . . . . . . . . U. S. Army Equipment Index of Modification Work Orders.
SB 38-100 . . . . . . . . . . . . . . . . . . Preservation, Packaging and Packing Materials, Supplies, and Equipment
Used by the Army.
TB 746-10 . . . . . . . . . . . . . . . . . . Field Instructions for Painting and Preserving Electronics Command
Equipment.
TB SIG 291 . . . . . . . . . . . . . . . . . Safety Measure to be Observed When Installing and Using Whip Antennas,
Field Type Masts, Towers, Antennas, and Metal Poles That Are Used with
Communication, Radar, and Direction Finder Equipment.
TM 11-666 . . . . . . . . . . . . . . . . . . Antennas and Radio Propagation.
TM 11-5985-262-15 . . . . . . . . . . Operator, Organizational, DS, GS and Depot Maintenance Manual Including Repair Parts and Special Tool Lists, Antenna AS-1729/vrc.
TM 11-5985-263-34P . . . . . . . . . Direct Support and General Support Maintenance Repair Parts and Special
Tool Lists (Including Depot Maintenance Repair Parts and Special Tools).
TM 38-750 . . . . . . . . . . . . . . . . . . The Army Maintenance Management System (TAMMS).
Change 2
A-1
TM 11-5985-263-15
APPENDIX B
BASIC ISSUE ITEMS LIST
Section I. INTRODUCTION
B-1. Scope
This appendix lists only basic issue items
required by the crew/operator for installation, operation, and maintenance of Mast
AB-903/G.
B-2. General
The basic issue items list (sec. II) is a
list, in alphabetical sequence, of items
which are furnished with, and which must be
turned in with the end item.
B-3. Explanation of Columns
The following provides an explanation of
columns found in the tabular listings:
a. Illustration. Not applicable.
b. Federal Stock Number. Indicates the
Federal stock number assigned to the item
and will be used for requisitioning purposes.
c. Part Number. Indicates the primary
number used by the manufacturer (individual, company, firm, corporation, or Government activity), which controls the design and characteristics of the item by
means of its engineering drawings, speci-
fications standards, and inspection requirements, to identify an item or range of
items.
d. Federal Supply Code for Manufacturer
(FSCM). The FSCM is a 5-digit numeric
code used to identify the manufacturer,
distributor, or Government agency, etc.,
and is identified in SB 708-42.
e. Description. Indicates the Federal
item name and a minimum description required to identify the item.
f. Unit of Measure (U/M). Indicates the
standard of basic quantity of the listed
item as used in performing the actual maintenance function. This measure is expressed by a two-character alphabetical abbreviation (e.g., ea, in., pr, etc.). When the
unit of measure differs from the unit of
issue, the lowest unit of issue that will
satisfy the required units of measure will
be requisitioned.
g. Quantity Furnished With Equipment
(Basic Issue Items Only). Indicates the
quantity of the basic issue item furnished
with the equipment.
Section Il. BASIC ISSUE ITEMS LIST
(1)
ILLUSTRATION
(A)
FIG
NO.
(B)
ITEM
NO.
(2)
FEDERAL
STOCK
NUMBER
(3)
PART
NUMBER
(4)
FSCM
(5)
DESCRIPTION
(6)
UNIT
OF
MEAS
(7)
QTY
FURN
WITH
EQUIP
EA
1
USABLE
ON CODE
5120-243-2985
GGG-H86
81349
HAMMER, HAND
Change 1
B-1
TM 11-5985-263-15
APPENDIX C
MAINTENANCE ALLOCATION
Section I. INTRODUCTION
C-1. General.
This appendix provides a summary of the maintenance operations for MAST AB-903/G. It authorizes categories of maintenance for specific
maintenance functions on repairable items and
components and the tools and equipment required
to perform each function. This appendix may be
used as an aid in planning maintenance operations.
C-2. Maintenance Function.
Maintenance functions will be limited to and
defined as follows:
a. Inspect. To determine the serviceability of an
item by comparing its physical, mechanical, and/or
electrical characteristics with established standards through examination.
b. Test. To verify serviceability and to detect
incipient failure by measuring the mechanical or
electrical characteristics of an item and comparing
those characteristics with prescribed standards.
c. Service. Operations required periodically to
keep an item in proper operating condition; i.e., to
clean (decontaminate), to preserve, to drain, to
paint, or to replenish fuel, lubricants, hydraulic
fluids, or compressed air supplies.
d. Adjust. To maintain, within prescribed limits,
by bringing into proper or exact position, or by
setting the operating characteristics to the
specified parameters.
e. Align. To adjust specified variable elements of
an item to bring about optimum or desired
performance.
f. Calibrate. To determine and cause corrections
to be made or to be adjusted on instruments or test
measuring and diagnostic equipments used in
precision measurement. Consists of comparisons of
two instruments, one of which is a certified
standard of known accuracy, to detect and adjust
any discrepancy in the accuracy of the instrument
being compared.
g. Install. The act of emplacing, seating, or fixing
into position an item, part, module (component or
assembly) in a manner to allow the proper
functioning of the equipment or system.
h. Replace. The act of substituting a serviceable
like type part, subassembly, or module (component
or assembly) for an unserviceable counterpart.
i. Repair. The application of maintenance services (inspect, test, service, adjust, align, calibrate,
replace) or other maintenance actions (welding,
grinding, riveting, straightening, facing, remachining, or resurfacing) to restore serviceability to an item by correcting specific damage,
fault, malfunction, or failure in a part, subassembly, module (component or assembly), end item, or
system.
j. Overhaul. That maintenance effort (service/
action) necessary to restore an item to a completely
serviceable/operational condition as prescribed by
maintenance standards (i.e., DMWR) in appropriate technical publications. Overhaul is normally
the highest degree of maintenance performed by
the Army. Overhaul does not normally return an
item to like new condition.
k. Rebuild. Consists of those services/actions
necessary for the restoration of unserviceable
equipment to a like new condition in accordance
with original manufacturing standards. Rebuild is
the highest degree of material maintenance
applied to Army equipment. The rebuild operation
includes the act of returning to zero those age
measurements (hours, miles, etc.) considered in
classifying Army equipments/components.
C-3. Column Entries.
a. Column 1, Group Number. Column 1 lists
group numbers, the purpose of which is to identify
components, assemblies, subassemblies, and modules with the next higher assembly.
b. Column 2, Compoment/Assembly. Column 2
contains the noun names of components, assemblies, subassemblies, and modules for which
maintenance is authorized.
c. Column 3, Maintenance Functions. Column 3
lists the functions to be performed on the item
listed in column 2. When items are listed without
maintenance functions, it is solely for purpose of
having the group numbers in the MAC and RPSTL
coincide.
d. Column 4, Maintenance Category. Column 4
specifies by the listing of a “worktime” figure in
the appropriate subcolumn(s), the lowest level of
maintenance authorized to perform the function
listed in column 3. This figure represents the active
time required to perform that maintenance function at the indicated category of maintenance. If
the number or complexity of the tasks within the
listed maintenance function vary at different
Change 2
C-1
TM 11-5985-263-15
maintenance categories, appropriate “worktime”
figures will be shown for each category. The
number of task-hours specified by the “worktime”
figure represents the average time required to
restore an item (assembly, subassembly, component, module, end item or system) to a serviceable
condition under typical field operating conditions.
This time includes preparation time, troubleshooting time, and quality assurance/quality control
time in addition to the time required to perform the
specific tasks identified for the maintenance
functions authorized in the maintenance allocation chart. Subcolumns of column 4 are as follows:
C — Operator/Crew
O — Organizational
F — Direct Support
H — General Support
D — Depot
e. Column 5, Tools and Equipment. Column 5
specifies by code, those common tool sets (not
individual tools) and special tools, test, and support
equipment required to perform the designated
function.
f. Column 6, Remarks. Column 6 contains an
alphabetic code which leads to the remark in
section IV, Remarks, which is pertinent to the item
opposite the particular code.
C-2
Change 2
C-4. Tool and Test Equipment Requirements (Sec IIl).
a. Tool or Test Equipment Reference Code. The
numbers in this column coincide with the numbers
used in the tools and equipment column of the
MAC. The numbers indicate the applicable tool or
test equipment for the maintenance functions.
b. Maintenance Category. The codes in this
column indicate the maintenance category allocated the tool or test equipment.
c. Nomenclature. This column lists the noun
name and nomenclature of the tools and test
equipment required to perform the maintenance
functions.
d. National/NATO Stock Number. This column
lists the National/NATO stock number of the
specific tool or test equipment.
e. Tool Number. This column lists the manufacturer’s part number of the tool followed by the
Federal Supply Code for manufacturers (5-digit) in
parentheses.
C-5. Remarks (Sec IV).
a. Reference Code. This code refers to the
appropriate item in section II, column 6.
b. Remarks. This column provides the required
explanatory information necessary to clarify items
appearing in section II.
TM 11-5985-263-15
SECTION
(1)
GROUP
NUMBER
00
(2)
COMPONENT/ASSEMBLY
MAST AB-903/G
II
MAINTENANCE ALLOCATION
FOR
MAST AB-903/G
(3)
MAINTENANCE
FUNCTION
Install
Inspect
Service
Adjust
Replace
Repair
Repair
Overhaul
CHART
(4)
MAINTENANCE CATEGORY
C
O
F
H
D
(6)
REMARKS
1 thru 7,9
0.8
0.1
(5)
TOOLS
AND
EQPT.
0.2
0.2
0.3
0.3
1.5
2.0
10
1 thru 7,9
1 thru 7,9
1 thru 7.9
1 thru 9
1 thru 9
C-3,
A
B
Change 2
TM 11-5985-263-15
SECTION III TOOL AND TEST EQUIPMENT REQUIREMENTS
FOR
MAST AB-903/G
TOOL OR TEST
EQUIPMENT
MAINTENANCE
CATEGORY
NATIONAL/NATO
STOCK NUMBER
NOMENCLATURE
REF CODE
1
F, H, D
TOOL KIT, ELECTRONIC EQUIPMENT TK-105/G
5180-00-610-8177
2
F, H, D
TOOL KIT, ELECTRONIC EQUIPMENT TK-100/G
5180-00-605-0079
3
C, F, H, D
SCREWDRIVER, FLT. TIP: LT. DTY; PLASTIC HANDLE; 0.030 IN. THK X
3/16 IN. WD TIP; 6 IN. NOM BLADE LENGTH
5120-00-260-4837
4
F, H, D
WRENCH ADJUSTABLE, OPEN END; SINGLE HEAD STEEL, CHROME OR NICKEL
PLATED, 6 IN. NOM. SIZE
5120-00-264-3795
5
F, H, D
WRENCH SET, SOCKET: SQ. DRIVE 3/8 IN. DRIVE SIZE: 12 PT: SOCKET;
W/CASE FED. SPEC. GGG-W-00641
5120-00-449-8149
6
F, H, D
WRENCH, TORQUE; RIGID FRAME END DRIVE STYLE DIAL INDICATING TORQUE
MECHANISM W/VISUAL INDICATING MECHANISM: 1/4 IN. SQ MALE DRIVE,
0 TO 75 INCH POUNDS RATED CAPACITY; W/CASE
5120-00-585-8434
7
F, H, D
WRENCH SET, SOCKET: 1/4 IN DRIVE SIZE; HEX AND 12 PT. SOCKETS:
W/CASE; FED SPEC GGG-W-00641
8
H, D
PLIERS, RETAINING RING (WALDEN KOHINOOR INC. #22)
5120-00-293-2513
9
F, H, D
0-60 POUND SPRING SCALE
6670-00-238-9777
10
O
TOOL KIT, ELECTRONIC EQUIPMENT
TK-101
* THE NATIONAL STOCK NUMBER THAT IS MISSING FROM THIS LIST HAS
BEEN REQUESTED AND WILL BE ADDED BY A CHANGE TO THE LIST UPON
RECEIPT.
C-4, Change 2
*
5180-00-064-5178
TOOL NUMBER
TM 11-59850263-15
SECTION
REFERENCE
CODE
IV.
REMARKS
REMARKS
A
CABLE TENSION AND WINCH BRAKE
B
REPLACE GUY ASSEMBLIES, ANCHORS, MOUNTING HARDWARE, AND PULLEYS.
C-5, Change 2
TM 11 5985-263-15
INDEX
Paragraph
Page
Adapter unit, counterpoise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-5
Additional equipment required . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-9
Adjustment:
Cable tension . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-5
Procedures, final . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-6
Winch brake . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-4
Antenna, orientation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4
Application, system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-10
Assemblies:
Brake . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-3
Cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4
Counterpoise tubes on antenna adapter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-9
Authority, demolition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-3
5-4
1-4
Base cap, replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Brake assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6-6
5-3
6-2
5-2
7-7
5-4
1-5
2-2
7-9
5-2
1-1
2-1
5-2
2-5
1-6
5-1
2-2
1-2
5-5
2-8
2-9
5-4
2-5
2-6
Demolition, authority . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-3
Description:
Components, mast AB-903/G . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2
Minor components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-8
Destruction, methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-4
Disassembly:
Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9-1
Mast AB-903/G . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-3
9-2
9-1
7-1
Equipment:
Additional . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Checking unpacked . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Disassembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Erecting mast . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1-9
2-2
9-1
2-7
1-4
2-1
9-1
2-2
Final adjustment procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Final testing procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Forms and records . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7-6
7-8
1-3
7-9
7-10
1-1
Ground installation, mast components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5
2-2
Inspections and physical tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Installation, mast components for ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6-8
2-5
6-2
2-2
Maintenance:
Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4-6
4-2
Cables:
Prestrech assemblies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tension, adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Characteristics, technical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Checking unpacked equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Components:
Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Mast, for ground installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Counterpoise:
Adapter unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Assembly and Antenna AS-1729/VRC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tubes, assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6-1
7-9
6-1
2-1
1-4
5-2
5-2
2-6
9-2
5-1
1-2
9-2
I-1
TM 11-5985-263-15
Paragraph
Page
Operator:
Daily preventive maintenance checks and service chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5
Preventive maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3
Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
Organizational:
Monthly maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Monthly preventive maintenance checks and services chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Preventive maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Quarterly preventive maintenance checks and services chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4-2
4-1
4-1
4-10
4-11
4-9
4-12
4-7
4-3
4-3
4-3
4-3
4-2
1-7
7-3
2-7
7-4
2-6
2-4
2-5
1-2
7-1
2-2
7-5
2-2
2-1
2-2
Depot maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Organizational maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Methods, destruction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Minor components, description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8-2
4-8
9-4
1-8
8-1
4-3
9 -2
1-2
Operating instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operation, general . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3-2
3-1
3-1
3-1
Mast AB-903/G:
Description . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . .
Disassembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Erecting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Reassembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Setup, preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Mast and antenna, orientation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Mast components, ground installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Materials and tools required:
Operator:
Daily preventive maintenance checks and services chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Preventive maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Preventive maintenance checks and service periods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Organization, troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Organizational:
Monthly maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Monthly preventive maintenance checks and services chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Preventive maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Quarterly maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Quarterly preventive maintenance checks and services chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tools and materials required . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Orientation, mast and antenna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4-5
4-3
4-7
4-1
6-3
4-2
4-1
4-2
4-1
6-1
4-10
4-11
4-9
4-12
4-13
4-7
4-8
2-4
4-3
4-3
4-3
4-3
4-3
4-2
4-3
2-1
Physical tests and inspections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Preparation, mast setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Prestrech cables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Publications, indexes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Purpose and use . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . .. . . . . . . . . . . . . . .
6-8
2-6
7-7
1-2
1-4
6-2
2-2
7-9
1-1
1-1
7-4
7-5
1-3
9-2
6-6
7-5
7-8
1-1
9-2
6-2
Reassembly:
Mast AB-903/G . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . ..
Winch assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Records and forms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Repacking, shipment or limited storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Replacement, base rep . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Scope:
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1-1
Operator maintenance . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
Organizational maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-7
Selection, site . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3
Setup, preparation for mast . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6
Shipment or limited storage, repackaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-2
Site, selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3
System application . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-10
I-2
1-1
4-1
4-2
2-1
2-2
9-2
2-1
1-4
TM 11-5985-263-15
Paragraph
Page
Table, components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
Technical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5
Testing procedures, final . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-8
Tools and equipment required:
Depot maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-2
Direct support maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-2
General support maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-2
Operator maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2
Organizational maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-8
Troubleshooting procedures, organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-3
Tubes, assembly of counterpoise on antenna adaptor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-9
1-2
1-1
7-10
Unpacked equipment, checking. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2
Unpacking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
Use, purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . .1-4
2-1
2-1
1-1
Winch:
Assembly, reassembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-5
Brake, adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-4
7-8
6-1
8-1
6-1
7-1
4-1
4-3
6-1
2-6
I-3
TM 11-5985-263-15
By Order of the Secretary of the Army:
W. C. WESTMORELAND,
General, United States Army,
Chief of Staff.
Official:
KENNETH G. WICKHAM,
Major General, United States Army,
The Adjutant General.
Distribution:
Active Army:
Ft Carson (7)
Ft Huachuca (5)
WSMR (2)
Svc Colleges (1)
USASCS (50)
USASESS (50)
Army Dep (2) except
LBAD (20)
SAAD (30)
TOAD (14)
ATAD (10)
LEAD (7)
NAAD (3)
SVAD (3)
Gen Dep (1)
Sig Sec, Gen Dep (4)
Sig Dep (6)
USACRREL (2)
USAERDAA (2)
USAERDAW (2)
Sig FLDMS (1)
Units org under fol TOE:
11-158 (1)
29-134 (1)
USASA (2)
CNGB (1)
Dir of Trans (1)
CofEngrs (1)
TSG (1)
CofSptS (1)
ACSC-E (2)
USAMB (10)
USAARENBD (2)
USCONARC (2)
USAMC (1)
USAMICOM (2)
USAECOM (2)
USAESC (70)
ARADCOM (2)
ARADCOM Rgn (1)
OS Maj Comd (2)
USACDCCEA (10)
USACDCCEA (1)
USACDCCEA (Ft Huachuca) (1)
USASTRATCOM (2)
USATECOM (2)
Armies (1)
1st Cav Div. (2)
ARNG: State AG (3).
USAR: None.
For explanation of abbreviations used, see AR 910-50.
✩ U.S. GOVERNMENT PRINTING OFFICE : 1994 O - 300-421 (82926)
Figure 5-1. Mast AB-903/G Cabling and pully diagram
PIN : 0 1 9 7 6 9 - 0 0 0
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