TM-11-5826-211-50

TM-11-5826-211-50
TM 11-5826-211-50
DEPARTMENT
DEPOT
OF
THE
ARMY
TECHNICAL
MAINTENANCE
MANUAL
MANUAL
R A D I O
M A G N E T I C
I N D I C A T O R
I D - 2 5 0 A / A R N
H E A D Q U A R T E R S ,
D E P A R T M E N T
DECEMBER
1959
O F
T H E
A R M Y
HEADQUARTERS,
DEPARTMENT OF THE ARMY
W ASHINGTON 25, D.C., 10 December 1959
TM 11-5826-211-50 (a reprint of an Air Force TO 12R5-2ARN-213, 1 October 1956) is
published for the use of Army personnel.
By Order of Wilber M. Brucker, Secretary of the Army:
L. L. LEMNITZER,
General, United States Army,
Chief of Staff.
Official:
R. V. LEE,
Major General, United States Army,
The Adjutant General.
Distribution :
Active Army:
USASA (2)
Def Atomic Spt Agcy (5)
CNGB (1)
Tech Stf, DA (1)
except CSigO (10)
Tech Stf Bd (1)
USA Arty Bd (1)
USA Armor Bd (1)
USA Inf Bd (1)
USA AD Bd (1)
USA Abn & Elct Bd ( 1 )
USA Avn Bd (1)
USA ATB (1)
USCONARC (5)
US ARADCOM (2)
US ARADCOM Rgn (2)
Log Cored (5)
MDW (1)
Armies 1 ) except
First US Army (3)
USATC (2)
NG: None.
USAR: None.
For explanations of abbreviations used, see AR 320-50.
USASCS (25)
Gen Dep (2) except
Atlanta Gen Dep ( None)
Sig See, Gen Dep (10)
Sig Dep (17)
USA Ord Msl Comd (3)
USASSA (15)
USASSAMRO (1)
USA Sig Pub Agcy (8)
USA Sig Engr Agcy (1)
USA Cornm Agcy (3)
USA Sig Eqp Spt Agcy (2)
USA Sig Msl Spt Agcy (2)
Fld Cored. Def Atomic Spt Agcy (2)
USA Elct PG (1)
Sig Lab (5)
USA Corps (Res) (1)
Units org under fol TOE:
11-587 (2)
11-592 (2)
11-597 (2)
T.O. 5N8-7-2-13
Table of Contents
Page
Section
I
II
III
INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1
1-1. Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1
1-2. Purpose of Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . .
1
1-3. Leading Particular. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1
OVERHAUL INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . .
1
2-1.
Special Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1
2-5.
Disassembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2
2-15. Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7
2-17. Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8
2-18. Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8
2-20. Repair or Replacement. . . . . . . . . . . . . . . . . . . . . . . . . . .
8
2-21. Lubrication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8
2-23. Reassembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8
TEST PROCEDURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13
3-1.
General . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . .
13
3-3.
Testing Ball Bearings . . . . . . . . . . . . . . . . . . . . . . . . . . .
13
3-4.
Testing Synchros . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13
3-6.
Setting Synchro Electrical Zero..... . . . . . . . . . . . . . . . .
13
3-7.
Testing Assembled Indicator . . . . . . . . . . . . . . . . . . . . . . .
15
3-10, Evacuating and Charging Indicator.. . . . . . . . . . . . . . . . . .
15
i
Section I
T.O. 5N8-7-2-13
Figure 1-1. Radio Magnetic Indicator ID-250A/ARN
Figure 1-2. Radio Magnetic Indicator less Covers
ii
T.O. 5N8-7-2-13
Sections I-II
SECTION I
1-1. IDENTIFICATION. This handbook contains overhaul and test instructions for Radio Magnetic Indicator
ID-250A/ARN (Borg Model 818). Sections II and III
contain overhaul and test instructions, Overhaul and
test instructions for additional models will be provided
in Section IV by the use of Difference Data Sheets,
The additional models will be listed in the Table of
Contents at the beginning of that section. This unit
(figures 1-1 and 1-2) is manufactured by the Borg
Equipment Division of the George W. Borg Corporatton, Janesville, Wisconsin.
1-2. PURPOSE OF EQUIPMENT, The indicator is
used in aircraft to display the magnetic bearing of
the aircraft and the magnetic bearings of two radio
stations, The instrument receives synchronous elec trical signals from a magnetic compass system and
two radio compass systems, and combines the radio
compass data with the magnetic compass data, It
indicates the magnetic heading of the aircraft on a
rotating dial, and the magnetic bearings of the two
radio stations under two pointers.
1-3. LEADING PARTICULARS.
GENERAL CHARACTERISTICS:
Length . . . . . . . . . . . . . . . . . . . . . . ..6-5 /16 in.
Width . . . . . . . . . . . . . . . . . . . . . . . . ..3-1/4 in.
Height . . . . . . . . . . . . . . . . . . . . . . . ..3-1/4 in.
Weight . . . . . . . . . . . . . . . . . . . ... . ..2-1/2 lb
Ambient temperature
range . . . . . . . . . -55°C to 70°C (-67°F to 158°F)
Barometric pressure
range . . . . . . . . . . . . . . . .3.5-in. Hg to 30-in. Hg
Accuracy:
a. Index (algebraic mean) , , . , . . . . ±0.25 degree
b. Maximum (at any setting) . . . . . . ±0.75 degree
ELECTRICAL CHARACTERISTICS:
Frequency, . . . . . . . . . . . . . . . . . . . . ..400cps
Applied volts:
a. Rotor . . . . . . . . . . . . . . ., . . . . . . ..26V ac
b. Stator . . . . . . . . . . . . . . . . . . . . ..ll.8V ac
SECTION II
OVERHAUL INSTRUCTIONS
2-1. SPECIAL TOOLS.
2-3. STANDARD OVERHAUL EQUIPMENT.
2-2. Table I lists the special tools and teat equipment required to perform the operation described in
this handbook.
2-4. Table II lists the standard overhaul equipment
required to perform the operations described in this
handbook,
TABLE I
SPECIAL TOOLS AND TEST EQUIPMENT
1
Section II
Paragraphs 2-5 to 2-7
T.O. 5N8-7-2-13
TABLE I (CONT)
SPECIAL TOOLS AND TEST EQUIPMENT
Nomenclature
Part Number
Service
Stock No.
Application
QB71520-1
V.T.V.M. cable
To connect vacuum tube voltmeter toomni-directional
instrument tester 13703-1-A.
QB72217-2
Bearing test rotor
Used with bearing torque teater 13716-1-A to test
ball bearings.
QB72218-1
Calibrator
To set up and check bearing torque tester 13716-1-A.
QB74218-I
Synchro adjusting wrench
To remove cap and adjust end play of Eclipse-Pioneer
synchro.
13638-1-B
Bearing cleaner
To clean and thoroughly dry ball bearings and small
parts. Bearing cleaning solution QB14634-1
required.
13693-1-A
Hermetic sealing stand
To seal, evacuate, fill, and leak-test instrument.
13700-1-A
or equal
Insulation tester
To test insulation for breakdown.
13703-1-A
Omni-directional instrument tester
To test indicator.
13716-1-A
Bear ing torque tester
To test ball bearings for starting torque and friction.
Used with bearing test rotor QB72217-2.
58534
Spanner wrench
Adjust end play of Oster synchro.
TABLE II
STANDARD TOOLS AND TEST EQUIPMENT
Nomenclature
Cat. No.
Manufacturer
Application
Model 1
Ohmmeter, 10-volt
Weston Electrical Instrument Co.,
Newark, NJ.
To make continuity and resistance checks.
31OA
Hand Remover K& D
Hamel Rigiander & Co.,
New York, N.Y.
To remove front and rear hand
assemblies and ring.
Hyper Vat. No
25 or equal
Vacuum pump
Central Scientific Co.,
Chicago, Ill.
To evacuate instrument.
Model 300
Vacuum tube voltmeter
Ballantine Laboratories,
Boonton, N.J.
To make voltage measurements,
2-5. DISASSEMBLY.
b. Remove four screws (7) and four iock washers
(8). Push back the 13 pieces of tubing (9) on four
2-6. DISASSEMBLY OF NAMEPLATE, END COVER,
AND ELECTRICAL CONNECTOR RECEPTACLE. (See figure 2-1.)
a. Remove the plastic cap nut (1), three screws
(3), and three lock washers (4), and place the instrument so that it rests on the electrical connector receptacle (6). Press down on nameplate (2) and end
cover (5), and lift off the rest of the instrument.
2
black insulated wires (10), three blue insulated
wires (11), three red insulated wires (12), and three
yellow insuiated wires (13); and unsolder the wires
from the electrical connector receptacle (6). Remove the receptacle and plug support plate (14).
2-7. DISASSEMBLY OF BEZEL, TERMINAL AS-
SEMBLY, COVER AND GLASS ASSEMBLY.
(See figure 2-1.)
Section II
T.O. 5N8-7-2-13
Figure 2-1.
3
Section II
T.O. 5N8-7-2-13
Figure 2-2. Mechanism Assembly, Exploded View
4
T.O. 5N8-7-2-13
. Remove eight screws (16) and eight lock washers,
(17) and slide bezel ring (15) from the rear of the
instrument. Remove the bezel (18) and gasket (19).
b. Cut off the end of the evacuating tube on terminal
assembly (21). Pry up the end of seal strip (20) and,
with pliers, peel it from the instrument,
c. Carefully force the edge of a sharp knife into the
soft solder junction of cover and glass assembly (25)
and terminal assembly (21), Slowly rotate the instrument, and, with a gentle prying motion, break
the rest of the solder junction.
Break the solder junction between the cover
glass assembly and the terminal assembly
with the utmost care to prevent damage to the
terminal assembly. Use a sharp knife, a
firm hand, snd just sufficient force to break
the junction.
d. Lift mechanism assembly (36) from cover and
glass assembly (25).
When lifting the mechanism assembly from
the cover and glass assembly, slide it out in
a straight line, Do not wiggle the mechanism
assembly from side to side, or damage will
result to the Instrument.
e. Remove three nuts (22), three lock washers (23),
and three shims (24); and lift terminal assembly (21)
away from mechanism assembly (36). Unsolder the
synchro leads from the terminal assembly.
NOTE
Do not disassemble cover and glass assembly (25) unless cover assembly (26) or cover
glass (28) requires replacement. Take care
not to injure the data warning decalcomania
(27) which is silk-screened on the cover assembly.
f. If it is necessary to separate glass (28) from
cover assembly (26), place cover and glass assembly (25) on a hot plate, glass down, until solder ring
(29) has melted; then lay the cover and glass assembly on its side, and press the glass out the rear end
of the cover assembly.
Section II
Paragraphs 2-8 to 2-12
b. With the hand remover, lift off the front and rear
hand assemblies (32 and 33).
c. Remove two dial screws (35) and dial (34) from
mechanism assembly (36).
2-9. DISASSEMBLY OF MECHANISM ASSEMBLY.
2-10. REMOVAL OF REAR SYNCHRO AND REAR
PLATE. (See figure 2-2.)
a. Remove pointer hub (1) from gear and shaft assembly (38). Remove three nuts (3), three lock
washers (4), and plate (2). Remove two pieces of
tubing (5). With index prism wrench QB3152-1, remove three rear posts (6), and lift off the rear plate
and rear synchro with the shaft.
When removing the synchro and rear plate
with the shaft, draw them back in a straight
line, taking care not to bend or injure the
shaft.
b. Remove shaft (7) from rear synchro (9). Remove
two screws (10), two lock washers (11), and two
clamps (12), releasing the synchro from rear plate
(13). Remove hub and wheel assembly (8) after removing the shaft and before proceeding’ with the rest
of the disassembly.
2-11. REMOVAL OF FRONT SYNCHROS AND GEAR
AND HUB ASSEMBLIES. (See figure 2-2.)
a. Holding the two synchros (14) in position, remove four screws (15), four lock washers (16), and
four clamps (17).
Care must be taken not to injure the gear and
hub assemblies while removing the synchros.
Hold the synchros in position until they are
loosened from the gear and hub assemblies.
b. Rest the mechanism assemblv on the three posts
(23), Insert a small drift in the hub of gear and hub
assembly (18) and tap gently with a plastic hammer
to drive synchro (14) from the assembly.
c. Repeat the procedure described in step b, to remove the second synchro (14) from the gear and hub
assembly (19).
d. Remove two synchro eccentrics (20). With index
prism wrench QB3152-1, remove three locating posts
(21), three clips (22), and three posts (23) from
gear train assembly (24).
Do not invert the cover and glass assembly
to drop the glass out of the assembly.
2-12. DISASSEMBLY OF GEAR TRAIN ASSEMBLY.
(See figure 2-2.)
2-8. DISASSEMBLY OF MASK, DIAL, AND HAND
ASSEMBLIES. (See figure 2-1.)
a. Remove three screws (26), three lock washers
(27), and. three washers (28). Lift front plate (25),
parts, from the shaft of gear and
with attached
shaft assembly 38).
a. Remove three screws (31) and mask (30).
5
Section II
Paragraphs 2-13 to 2-14
T.O. 5N8-7-2-13
synchro adjusting wrench QB74218-1, remove cap
(2).
When lifting the front plate, take care to
lift it straight up to avoid damaging the
shaft of the gear and shaft assembly.
b. Remove three nuts (30) and three washers (31)
which secure bearing plate assembly (29). Do not
remove the three posts unless they must be replaced.
c. Using a block of wood with a hole drilled to receive dial hub (35), rest front plate (25) on its
front face. With the hand remover, lift off ring
(32). Remove gear and shaft assembly (33). Separate the front plate and dial hub. Remove gear
and shaft assembly (38) from mechanism plate assembly (40).
d. Do not press jewel (34) from dial hub (35),
jewel (36) from front plate (25), jewel (37) from
bearing plate assembly (29), or jewel (39) from
mechanism plate assembly (40) unless they require replacement.
2-13. DISASSEMBLY OF ECLIPSE-PIONEER RECEIVER SYNCHROS. (See figure 2-3.)
a. With a screwdriver, carefully pry the ends of
retainer clip (1) from the end of the synchro. With
b. Press the protruding end of the rotor shaft to
free rear housing (4), remove rear housing, mounting plate assembly (6) and rotor assembly (9) from
the synchro as a unit. Remove tubing (5).
c. Remove the rear housing from the rotor assembly. Disengage the mounting plate assembly and
rotor assembly, taking care not to injure the brushes.
Using bearing pusher QB71479-1, press the ball
bearings (3) from rear housing (4) and front housing assembly (12).
d. If necessary for replacement, unsolder black
insulated wire (7) and red insulated wire (8) from
mounting plate assembly (6).
e. Remove spacer (10) and spring washer (11) from
front housing assembly (12).
2-14. DISASSEMBLY OF JOHN OSTER RECEIVER
SYNCHROS. (See figure 2-4.)
a. Remove two machine screws (3) attaching end
cover (2) to Receiver Synchro (1). Carefully remove cover from synchro, allowing the electrical
Figure 2-3. Eclipse-Pioneer Receiver Synchro, Exploded View
6
T.O. 5N8-7-2-13
Section II
Paragraph 2-15
Figure 2-4. John Oster Receiver Synchro, Exploded View
leads to be drawn through two grommets (4). R e move the grommets, if “necessary for replacement.
b. Remove machine screw (6) and lock washer (7)
which attach clamp (5) to bearing housing (12).
Remove the clamp, rotor insulator sleeve (6), and
stator insulator sleeve (9).
c. Take off brush and leads holder (10) by removing
attaching machine screw (11); take care not to damage the brushes when removing them from their
grooves in the slip rings.
f. Remove spring tension washer (16). Do not attempt to remove stator assembly (17) or identification plate (16) from housing (19). These three
parts are not procurable separately but are supplied
as an assembly.
2-15. CLEANING.
a. Clean all parts except the ball bearings by wiping
with a lint-free cloth and brushing with a hair or fiber
brush. If necessary, use a cloth lightly moistened with
dry cleaning solvent Federal Specification P-S-661A,
or another approved solvent.
d. Bearing housing (12) is locked in housing (19)
by threaded ring (13), Use spanner wrench 58534
to remove this ring and free the housing.
e. Remove rotor assembly (14) and two ball bearings (15). (Ball bearings are sliding fit in housing
counterbores and hand-push fit on shaft journals.)
Do not disassemble the rotor assembly.
Do not use ordinary carbon tetrachloride
or compressed air to dry parts. The use
of either will cause corrosion.
7
Section II
Paragraphs 2-16 to 2-24
T.O. 5N8-7-2-13
b. Carefully remove all solder from the cover and
glass assembly and the terminal assembly to insure even seating of parts when the instrument is
reassembled.
c. Cover all parts after cleaning to keep them dust
free.
2-16. CLEANING BALL BEARINGS. Clean and lubricate ball bearings as follows:
a. Use bearing cleaning tool kit QB70606-1, bearing cleaner 13638-1, and bearing cleaning solution
QB14634-1, or dry cleaning solvent Federal Specification P-S-661A for handling, washing, and lubricating ball bearings.
b. Select or assemble a mandrel from the bearing
cleaning tool kit, Put the bearing on the mandrel
with tweezers, and place the retainer over the bearing.
Always use tweezers to handle bearings.
Fingering bearings will cause corrosion.
c. Connect and adjust bearing cleaner 13638-1 (figure 2-5). Hold the bearing 3/16-inch from the jet and
allow the jet to clean the bearing thoroughly. Turn
one of the bearing races slowly to dislodge dirt or
chips from around the bearing balls and their separator,
Do not allow the bearing to spin on the mandrel. The lapping caused by the dirty solvent will ruin the bearing.
d. Turn off the jet, and set the selector valve (11,
figure 2-5) in the horizontal position. Dry the bearing completely in the air flow at outlet (3). Immedi ately after drying, lubricate per paragraph 2-21.
2-17. INSPECTION.
a. Examine all parts of the indicator for cracks,
chipping, corrosion, and excessive wear. Examine
all threaded components for stripped and worn threads
or other damage. Repair or replace damaged and
worn parts prior to reassembly.
b. Inspect the slip rings and brushes for discoloration. Remove even the slightest discoloration by
polishing with fine crocus cloth and wiping clean with
the glossy side of soft tissue paper. If excessive wear
or pitting is found, replace the part.
2-18. TESTING.
2-19. Test the rotor and stator resistances with the
ohmmeter, If rotor resistance does not lie between
14.4 and 17.6 ohms, or stator resistance does not lie
between 5.5 and 6.7 ohms, replace the defective part.
not been applied to these parts, or if the anti-corrosive
coating is scratched, apply a new lacquer coating.
Wipe off all defective coating with lacquer thinner
(Roxalin Thinner No, 75), and polish laminated faces
with No. 0000 emery cloth until surfaces are smooth
and clean. Do not touch surfaces with fingers. After
polishing, clean the rotor and stator assemblies
with blasts of clean, dry air. Wipe the surfaces to
be treated with a cloth dampened in lacquer thinner
until all grit and foreign matter have been removed.
Allow the rotor and stator to dry thoroughly.
b. Mask all surfaces not to be treated with masking
tape, and heat the parts to approximately 16.6°C
(30° F) above ambient temperature. While the Parts
are warm, spray the laminated surfaces with a thin
coat (0.0002 -inch maximum thickness) of Paladin
Black Finish No. 12412, mixed with enough Roxalin
Thinner No. 75 to prevent cobwebbing of sprayed
surfaces.
c. Bake finish for one hour at 121°C (250° F), remove parts from oven, and allow to cool at room
temperature. If oven is not available, air dry. Do
not reassemble parts until thoroughly dry and do not
scratch coating.
2-21. LUBRICATION.
2-22. Immediately after drying, lubricate bearings
with two drops of lubricating oil, Specification MIL L-6085, using a syringe. Do not allow the syringe
to touch the bearing. Make certain that all surfaces
of the bearings are coated with oil. Test ball bearings as outlined in paragraph 3-3.
It is imperative that the bearing be lubricated
immediately after cleaning. Inspect bearing
for flaws, corrosion, or other damage; then
lubricate. After oiling bearing, place in a
clean, dust -proof container until ready for use,
2-23. REASSEMBLY.
2-24. REASSEMBLY OF ECLIPSE - PIONEER RECEIVER SYNCHROS. (See figure 2-3.)
a. Slip tubing (5) over the stator leads of the front
housing assembly (12).
b. With bearing pusher QB71479-1, install the two
ball bearings (3) in the front housing assembly (12)
and the rear housing (4). Select ball bearings for a
handpush fit in housings and a sliding fit on the shaft
of rotor assembly (9).
c. Place spring washer (11) and spacer (10) in front
housing assembly (12), keeping the stator leads clear,
2-20. REPAIR OR REPLACEMENT.
d. If the black and red insulated wires (7 and 8) have
been removed, solder them to their respective places
on mounting plate assembly (6).
a. Check the ground surfaces of the synchro rotor and
stator for corrosion. If anti-corrosive treatment has
e. Place mounting plate assembly (6) in synchro
brush jig QB71482-1, so that the brush blocks and
8
T.O. 5N8-7-2-13
leads fit into the holes provided for them. Form
the brushes so that the edges (not the flat surfaces)
of the brushes will ride on the rotor assembly slip
rings and provide continuous electrical contact. If
greater brush tension is desired, use the small set
of brush jig slip rings. Make a final adjustment of
the brushes when rotor assemblv (9) is reassembled
with mounttng plate assembly (6) and rear housing(4).
Section II
f. Position mounting plate assembly (6) on rear
housing (4) so that the brush blocks and leads fit into
the boles provided for them. Carefully place shaft
of rotor assembly (9) in ball bearing (3) In rear
housing, placing the slip rings of the rotor shaft between tbe brushes. Make a final check and adjustment to obtain a correct setting for the brushes with
maximum contact as instructed in step e.
Figure 2-5. Bearing Cleaner
9
Section II
Paragraphs 2-25 to 2-27
T.O. 5N8-7-2-13
g. Carefully slip shaft of rotor assembly (9) In
front housing ball bearing(3). Gently bring housings
together with key in rear housing (4) fitting into the
slot in the front housing assembly (12).
h. Slip cap (2) over the stator and brush leads.
With synchro adjusting wrench QB74218-1, screw the
cap on front housing assembly (12) until the rotor
shaft has 0.0015-inch end play with a one-ounce load
and 0.004-inch end play with a one-pound load. Two
notches in the cap must be in line with each hole in
rear housing (4), Snap retainer clip (1)’ into place.
2-25. REASSEMBLY OF JOHN OSTER RECEIVER
SYNCHROS, (See figure 2-4.)
a. Reassembly of the John Oster Receiver Synchro
is essentially the reverse of disassembly. Refer to
the instructions prescribed in paragraph 2-14 and to
the index sequence of figure 2-4 to reassemble this
synchro.
b. Threaded ring (13) must be tightened down (using
spanner wrench (58534) in housing (19) until the shaft
of rotor assembly (14) has 0.0015-inch end play with
a one-ounce load and 0.004-inch end play with a onepound load.
c. Particular care must be taken that the brushes
on brush and leads holder (10) have correct alignment
and tension in the clip ring grooves of rotor assembly (14).
2-26. REASSEMBLY OF GEAR TRAIN ASSEMBLY.
(See figure 2-2.)
a. If necessary, replace the three posts in the mechanism plate assembly and the three posts in the
bearing plate assembly. Spin the peats over against
the rear of the plate tightly.
b. Press jewel (39) into mechanism plate assembly
(40) until it is flush with the plate front face.
c. Assemble bearing plate assembly (29) to front
plate (25) with three nuts (30) end three washers (31),
but do not tighten the nuts. Assemble the front
plate to the mechanism plate assembly with three
screws (26), three lock washers (27), and three
washers (28), but do not tighten the screws.
d. Press jewel (37) into bearing plate assembly (29)
until it is flush with the aide opposite the mounting
studs.
e. Press jewel (36) into front plate (25) until its
larger diameter is 0.003 to 0.005 inch above the surface plate,
f. Press jewel (34) as far into dial hub (35) as it
will go.
g. Place dial hub (35) through jewel (36) in front
plate (25), inserting a 0.010-inch shim (slotted to
receive the dial hub shaft) between the bearing surfaces of the dial hub and jewel. Place gear and shaft
assembly (33) on the shaft of the dial hub, and slip
10
ring (32) over the split hub of the gear and shaft
assembly. Press the ring tightly on the split hub,
and stake it lightly with staking punch QB71033-3.
Remove the shim from between the dial hub and the
jewel.
h. Secure front plate (25) and bearing plate assembly (29) by tightening three lock washers (31) and
three nuts (30), Check that dial hub (35) does not
rest against the jewel in the front plate in any way.
Check the end play of the dial hub. It should be
0.004 (±0.002) inch. If the dial hub rests against the
jewel in the front plate, adjust the setting of the jewels in the front plate and the bearing plate. If the
end play of the dial hub is out of tolerance, readjust
jewels mentioned in the previous sentence. Place the
rear shaft of gear and shaft assembly (38) in jewel
(39) which was previously installed in mechanism
plate assembly (40), Lower the front plate and
attached parts over the front shaft of gear and shaft
assembly (38) so that the shaft passes through the
hub of gear and shaft assembly (33) and protrudes
slightly from the front of dial hub (35).
When assembling gear and shaft assembly
(38), be careful not to bend or damage shaft.
i. Secure front plate (25) to mechanism plate assembly (40) by tightening three screws (26), three lock
washers (27), and three washers (28).
j. Check the end play of the two gear and shaft
assemblies (33 and 38). In each case, the end play
should be 0.005 (±0.002) inch. If the end play does
not fall within these limits, readjust the setting of
the jewel in mechanism plate assembly (40).
2-27. REASSEMBLY OF MECHANISM PLATE ASSEMBLY. (See figure 2-2.)
a. With index prism wrench QB3152-1, replace
three posts (23), three clips (22), and three locating
posts (21) on gear train assembly (24).
b. Place two synchro eccentrics (20) in mechanism
plate assembly (40), with their high sides at the center, Attach two synchros (14) with four clamps (17).
four screws (15), and four lock washers (16), but do
not tighten the screws. Place two pieces of tubing
(5) on the synchro leads.
c. Place shaft (7) in a pin vise; set the rear synchro
(9) face up on the bench, and guide the shaft into the
bushing in the synchro shaft. With a light plastic
hammer, tap the top of the pin vise lightly to drive
the shaft into the bushing, Remove the pin vise.
Be careful not to drive the shaft too deeply
into the synchro bushing. Tapping too hard
will injure the bushing and the shaft.
d. After inserting shaft (7) in rear synchro (9) as
instructed in step c, place the synchro in position on
T.O. 5N8-7-2-l3
FIGURE 2-2
Section II
Paragraph 2-27
FIGURE 2-2
FIGURE 2-2
FIGURE 2-2
Figure 2-6. Gearing Arrangement
the unattached rear plate (13), and lightly secure it
with two clamps (12). two lock washers (11). and two
screws (10). Place hub and wheel assembly (8) over
the shaft, and press it on the hub of the rear synchro
shaft. Check the distance between the rear of the
hub and wheel assembly and the front of the rear
plate for adequate clearance of rotating parts. With
three rear posts (6), secure the rear plate to three
posts (23), using index prism wrench QB3152-1 to
tighten the posts. Check the distance from We end
of the shaft (7) to the front of the mechanism plate
assembly (40). This distance should be 0.640 (±0.010)
inch. Remove the hub and wheel assembly when
reaming the rear synchro bushing if rear shaft (7)
must be reseated to meet this dimension.
the clamps almost completely, being careful not to
disturb the gear mesh.
g. Press gear and hub assembly (19) on the shaft of
its synchro (14). Mesh the gears, and adjust synchro
eccentric (20) as instructed in step f.
2-27. REASSEMBLY OF MAIN ASSEMBLY. (See
figure 2-1.)
e. Place plate (2) on rear posts (6), and secure with
three lock washers (4) and nuts (3). Set the instrument upright on the plate, and press pointer hub (1)
onto gear and shaft assembly (38).
a. Place dial (34) on dial hub (35, figure 2-2) and
secure with two dial screws (35, figure 2-1). Replace mask (30) and secure with three dial screws
(31). Press rear hard assembly (33) on pointer hub
(1, figure 2-2) and front hand assembly (32, figure
2-1) on shaft (7, figure 2-2). If the front hand assembly does not fit the shaft, ream slightly with 3-degree
taper reamer QB70015-6. U the rear hand assembly
does not fit the pointer hub, ream slightly with 3-degree taper reamer QB70015-2.
f. Press gear and hub assembly (16), on the shaft of
its synchro (14). Press the gear and hub assembly
down on the synchro hub until the teeth of gear and
shaft assembly (38) are centrally meshed in the teeth
of the gear and hub assembly as shown in figure 2-6.
If necessary, ream the hub of the. gear and, hub assembly with a 3-degree taper reamer. When the
gear faces are adjusted, slightly loosen two clamps
(17) and, with gear preload holder QB71024-1, adjust
synchro with minimum friction and backlash, tighten
b. If cover glass (28, figure 2-1) was removed from
cover assembly (26), replace it with a new glass.
Place the new cover glass in the cover assembly, and
lay solder ring (29) over the glass. Place the assembled parts on a hot plate to effect a proper joint.
If the solder ring ldoes not supply enough solder, add
a slight amount of solder with a melting range of
181°C to 213°C (357°F to 416° F) along the joining of
the glass cover assembly. Do not use flux in this
operation. Remove any solder from the outer sur11
Section II
T.O. 5N8-7-2-13
face of cover and glass assembly (25). When the
cover glass has assumed Its proper position due to
solder flow, push the assembled parts to an adjoining
surface on the same level as the hot plate, and allow
the parts to cool undisturbed. Place the cover and
glass assembly face down on the scraping fixture of
hermetic sealing stand 13693-1-A, and rotate it to
scrape off excess solder from the front of the cover
and glass assembly. Teat the cover and glass assembly for leaks, using the clamp fixture in the hermetic sealing stand. Place the clamp around the
cover and glass assembly so that the rear opening of
the cover assembly is sealed off. Connect the output on the clamp to the Hyper Vac. No. 25 vacuum
pump. Fill the cover and glass assembly to 15
psi, and check for leaks by immersing it in water.
Dry the assembly completely after testing for leaks.
c. Check mechanism assembly (36) in cover and
glass assembly (25) for proper distance of the hands
from the cover glass. Place a fiber spacer 1/32inch thick and of slightly smaller diameter than the
cover glass in the cover and glass assembly, Push
the mechanism assembly into the cover and glass
assembly in a straight line so that front hand assembly (32) rests against the fiber spacer. Select shims
(24) so that when they are placed on terminal assembly (21), the terminal assembly will rest tightly
against the rear end of the glass assembly. The
shims are 0.015-inch and 0.047-inch thick, respec tively. When the correct shims have been selected,
remove the terminal and mechanism assembles,
and fiber spacer from the cover and glass assembly.
d. Resolder the synchro leads to terminal assembly
(21) as shown in figure 2-7. Secure the terminal
assembly to mechanism assembly (36, figure 2-1)
with the shims (24) selected in paragraph c, three
lock washers (23) and three nuts (22).
e. Secure electrical connector receptacle (6) to ptug
support plate (14) with four lock washers (8) and
four screws (7). Place thirteen pieces of tubing (9)
on four black insulated wirea (10), three blue insulated wires (11), three red insulated wires (12),
and three yellow insulated wires (13). Refer to
figure 2-7 and resolder the thirteen wires to terminal
assembly (21, figure 2-1) and the electrical connector
receptacle. Push the 13 pieces of tubing down over
the receptacle terminals.
f, Calibrate and set electrical zero for dial (34) and
the front and rear hand assemblies (32 and 33) as
Instructed in paragraph 3-6 in Section III.
g. Place bezel (18) face down on the bench. Select
a gasket (19) of sufficient thickness so that cover and
glass assembly (25) will be properly seated in the
bezel. Place the gaaket in the bezel, and set the
cover and glass assembly in the bezel. Slide bezel
ring (15) onto the cover and glass assembly and
secure it to the bezel with eight lock washers (17)
and eight screws (16).
h. Press cover and glass assembly (25) down over
mechanism assembly (36) until terminal assembly
(21) rests tightly on the open end of the cover and
glass assembly, Lay a length of thin wire solder with
a melting range of 181°C to 213°C (357°F to 416°F)
around the joint of the terminal assembly and the
cover and glass assembly where seal strip (20) is to
be placed, Progressively colder the seal strip into
place around the juncture of the cover and glass
assembly and the terminal assembly, keeping the
seal strip as flat as possible, When finished, allow
instrument to cool, and clean off any roughness or
excess solder.
i. Temporarily fasten end cover (5) and nameplate
(2) to the instrument with three lock washers (4) and
three screws (3), and place plastic cap nut (1) on
electrical connector receptacle (6).
Figure 2-7. Internal Wiring Diagram
12
T.O. 5N8-7-2-l3
SectIon III
Paragraphs 3-1 to 3-6
SECTION III
3-1. GENERAL.
3-2. Except where pressure and temperature are
directly specified, tests should be conducted at
atmospheric pressure (approximately 29.92 in. Hg)
and room temperature (approximately 25° C (77° F)).
When tests are made with a substantially different
atmospheric pressure or room temperature, allowance must be made for that difference.
180 degrees. Make five or six starts in each direction of rotation. If the test rotor does not rotate for
each start, the bear ing should be removed from the
rotor, recleaned, relubricated, and retested. If the
bearing falls the tests a second time, discard it.
3-3. TESTING BALL BEARINGS.
a. Place the ball bearing on a suitable mandrel
selected from bearing cleaning tool kit QB70606-1.
set the ball bearing spinning slowly. Smoothness of
bearing action can be felt by the fingers holding the
mandrel; rotation should be so smooth that no vibration or roughness is apparent. Should the retainer
slow down abruptly, stop suddenly, or reverse direction slightly, the ball bearing must be rewashed,
relubricated, and retested with the mandrel. If the
bearing fails the second test, discard it.
b. Connect bearing torque tester 13716-1-A to the
air supply outlet of bearing cleaner 13638-1-B with
¼-inch aluminum or copper tubing. Level the
bearing torque tester. Adjust the external air pressure regulator of the bearing cleaner to givea pointer
deflection on tile bearing torque tester of about “7”.
Set calibrator QB72218-1 on the bearing torque tester
against the guide. With air supplied to the bearing
torque tester, adjust the air pressure knob at the
right side of the tester until the dial on the calibrator
reads the required starting torque of 1400 milligrammillimeters. Adjust the pilot lamp knob at the left
side of the torque tester until the tester pilot lamp
lights when the calibrator reads the required starting
torque. The pilot lamp must light at exactly this
starting torque, not at a lower or higher value. It
may be necessary to readjust the knob at the right
side of the tester since the adjustment of the pilot
lamp knob slightly changes the pressure of the air
and, therefore the calibrator reading. After the
knobs are correctly set, lock the pilot lamp knob
with the lock nut. Turn the air pressure knob to
reduce the air pressure to a small value. Remove
the calibrator from the tester.
c. With tweezers, mount the ball bearing on the
mandrel of bearing test rotor QB72217-2. Set the
rotor over the ball bearing. Position the rotor
against the test guide of the bearing torque tester.
Slowly turn the air pressure knob at the right side of
the bearing torque tester to increase the air pressure.
The rotor must rotate at least 360 degrees before
the red pilot lamp lights. Repeat the test for the
opposite direction of test rotor rotation. This is
done by turning the jet of the bearing torque tester
d. Immediately install each ball bearing that tests
satisfactorily, or store In a clean, dry, covered
container. Cover a bearing that is stored with the
same oil (Specification MIL-L-6085) with which it is
lubricated.
3-4. TESTING SYNCHROS.
3-5. INSULATION BREAKDOWN TEST. With insulation tester 13700-1-A, apply 550 volts at 60 cps
across one stator lead and ground (housing). No
Insulation breakdown should occur. Apply the same
voltage across one rotor lead and the housing. No
insulation breakdown should occur,
3-6. SETTING SYNCHRO ELECTRICAL ZERO.
(See figure 3-1.)
a. Place the partially assembled Radio Magnetic
Indicator in rack (3) on top of the omnl-directional
instrument tester 13703-1-A, Plug the ID250 tester
connector cable into the Radio Magnetic Indicator.
b. Set main selector switch (20) at “ID250 TEST
SEL”.
c. Connect the three power sources (28-volt dc,
117-volt 80 cps, and 115-volt 400-cps) to the instrument tester. Set power switches (24) at "ON".
d. Set the ID250 test, selector (5) switch at “DIAL
CARD".
e. Set standard transmitter (6) at zero degrees.
f. Loosen the radio magnetic indicator dial card
synchro clamps, and carefully rotate the synchro
until the dial card zero is at the large pointer on the
mask. Tighten the clamps so the dial card aynchro
is secured in the zero position.
g. Set ID250 test selector switch (5) at “POINTER
NO. 1". Loosen the front hand assembly synchro
clamps of the Radio Magnetic Indicator. Use the
procedure described in step f, and set the front hand
assembly of the Radio Magnetic Indicator on the 180
13
Section III
T.O. 5N8-7-2-13
Figure 3-1. Omni-Directional Tester 13703-1-A
14
T.O. 5N8-7-2-13
Section III
Paragraphs 3-7 to 3-10
degree position.
NO. 2", and repeat steps d and e.
h. Set the ID250 test selector stitch at “POINTER
NO. 2". Loosen the rear hand assembly synchro
clamps of the Radio Magnetic Indicator. Use the
procedure described tn paragraph f, and set the rear
hand assembly on the 180 degree position.
3-9. FRICTION ERROR TEST.
a. Tap the Radio Magnetic Indicator firmly but
gently during each of the tests described in paragraph
3-8 before turning the test selector swttch to the
next position.
3-7. TESTING ASSEMBLED INDICATOR.
3-8. ROTATION AND SCALE ERROR TEST. (See
figure 3-1.)
b. The dial friction error of the Radio Magnetic
indicator should not exceed two degrees. The fric tion error of the pointers should not exceed one
degree.
NOTE
Before performing this test, read paragraph
3-9.
a. Place the assembled Radio Magnetic Indicator in
rack (3) on top of the omni -directional instrument
tester 13703-1-A. Perform the procedures described
in paragraph 3-6, steps a through e. Set standard
transmitter (6) at exactly zero degrees. indicator
must read zero degrees (±0.75 degrees). Record
the indicator reading.
b. Set standard transmitter (6) at exactly 30 degrees
and record the reading of indicator. Continue resetting the transmitter in 30-degree increments
through its entire 360-degree range, recording the
indicator reading after each new setting of the transmitter. No indicator reading taken during this test
should vary from the standard transmitter setting
by more than 0.75 degree.
c. When all 13 settings (the zero-degree and 360degree settings coincide) have been recorded, algebraically add the differences between the standard
transmitter settings and the indicator readings and
divide the sum by 13. The answer should not exceed
0.25 degree.
d. Set the ID250 test selector switch (5) at “POINTER NO. 1”, and set standard transmitter (6) at exactly
zero degrees. The Indicator must read 160 (30.75)
degrees.
e. Repeat the procedure described in steps b and c,
above, except that the 160-degree difference between
standard transmitter setting and indicator reading
must be subtracted each time to account for the 180degree electrical zero relationship.
f. Set the ID250 test selector switch at “’POINTER
3-10. EVACUATING AND CHARGING INDICATOR.
(See figure 2-1.)
a. Remove plastic cap nut (1), three screws (3),
three lock washers (4), end cover (5) and nameplate
(2).
b. Using the Hyper Vat. No. 25 vacuum pump in
conjunction with hermetic sealing stand 13693-1-A,
evacuate the instrument through the evacuation tube
on terminal assembly (21) to a pressure of 1 0 0
microns or less. Check the gage on the hermetic
sealing stand. When the pressure has been reached,
shut off the evacuating pump, and fill the instrument
with a mixture of 90-percent nitrogen and 10-percent
helium to a pressure of one atmosphere as read on
the hermetic sealing stand gage. Pinch off the
evacuating tube approximately 1/4 inch from its end.
Remove the instrument from the hermetic sealing
stand and fill the end of the evacuating tube with
solder.
c. Immerse the indicator In a jar of water. The jar
and airtight cover are included in the hermetic sealing stand. Reduce the absolute pressure of the air
above the water in the jar to approximately 1 in. Hg,
and maintain the pressure until air bubbles substantially cease to be given off by the liquid, or
approximately one minute, whichever is longer. Increase the absolute pressure to 2-1/2 in. Hg. Bubbles which come from within the indicator are considered leakage, and the indicator must be rechecked
for air tightness. Correct the leakage, and repeat
the hermetic sealing procedure.
d. Upon successful completion of the leakage test,
remove the indicator from the jar and dry thoroughly.
Install end cover (5) and nameplate (2) with three
lock washers (4) and three screws (3). Screw on the
plastic cap nut (1).
15
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