PENTAX T 24B, GT 4B, GT 6B Transit Operating Instruction Book

 PENTAX / GEOTEG
TRANS
ASAHI PRECISION CO., LTD.
Miyakezaka Bldg., Nagata-cho, 1-11-1, Chiyoda-ku, Tokyo, 100, Japan
PENTAX OPERATING INSTRUCTION BOOK
Printed In Japan
MEMO
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Checking
Before measurement, an instrument should be examined according to
this instruction book. If necessary, the instrument should be adjusted.
Even a new instrument or completely repaired instrument need to be
checked. This procedure is also recommended during long intervals of
non-use or after long journey. At the end of field season, it is recom-
mendable the instrument shouid be checked by repairman in a
distributor,
Unpacking
When unpacking an instrument from a container, please notice carefuliy
and to remember how it is fastened in the container so that repacking
after use may be correctly and easily. Notice to lift the instrument from
the container with both hands. Refer to page 15 packing item concern-
ing other details.
Setting up
When install or remove the instrument on the tripod, the instrument
should be kept with one hand. The instrument shouid never be left an
tripod without being fastened with center screw. Such a thing causes
big accident.
if these hints, the instruction book and plain common sense are fni-
lowed, the instrument should give good service and have a long life,
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CONTENTS
1. Technical Data .. .. 212222 4 44 4 24024 4 24 4 0
2. Description .. . 12222044 4 14 44 4444 4 844 5
2-1 T-24B.. 1.210222 24124 4 8 4 2 44 4 4 4 44e
2-2 GTAB,GT-BB. .......... «co...
3. Preparation for Measuring . . . . . . .. ere:
3-1 Setting up the Instrument and the Tripod. . . .
3-2 Levelingup by Plate Level . . . . . ........
3-3 Centering under Roof Point. . . . . .. .....
4. Measuring . . 1 112224404444 404 4 4 4 4 4 4 4 4 40
4-1 Focusing and Sighting .. .. 2.222424 2420
4-1-1 Reticle Cross Hatrs . . . 2.222242 41220
4-1-2 Target mage Focusing . . . . . . .......
4-1-3 Sighting . . . .. oo
4-2 Circle Reading. . 1. 1.222224 44 4 4 2 4240
4-2-1 Horizental Circle © ©. ©... . . . . . . ...
4-2-2 Vertical Circle. . . . 1.420444 44 41240
4.3 Setting Horizontal Circle to Required Value.
4-4 Stadia Surveying . . . . . e... e ed,
5. Care and Maintenance .. 2. 1.221024 2441411000
6. Optional Accessories . . 1. 1 2114444 1244 14440
6-1 Electric H{tmination .. 1.124244 441420
6-2 Diagonal Eyepiece .. 2... 222214442420
6-3 Eyepiece Sunglass. .. 22222 4 22 4 1 1 222 0
7. Testing and Adjusting . . 1... 2222441 24 124000
7-1 Tripod . . 1120220102 41424 41 4 11 1 224 0
1-2 Plate Level. . . . 1 1101414442 144 1 4 42 0
7-3 Circular Bubble .. 1. 121102020444 14112120
7-4 Horizonta! Collimation Error . . . . . . . . .. .
7-5 Telescope Level . , . . 220242022414 2 4 14 0
7-6 Index Error .. 1.222212 221 4 4 1 2 1 14 0
7-7 Optical Plummet {OP}... ...........
2. Looking through the optical plummet, by turning foot screws, coin-
cide intersection of O.P. cross line with intersection of cross line
drawn on white paper.
Turn the alidade through 180° and lock through optical plummet
and check whether intersection of O.P. cross line and intersection
of cross line which is drawn on white paper coincide. If they do not
coincide, adjustment is necessary.
Adjustmant
1.
bDiaw straight line between two point: the one peint sighted by
intersection of O.P. cross line and the other point of intersection
of cross line drawn on white paper and adjust three adjustment
screws so as that O.P. sights the center point, (See Fig. 19.)
By turning the alidade through every 90°, repeat adjustment until
the intersection of OP. cross line and the intersection of cross line
on the white paper always coincide. In these adjustment and inspec-
tion, the instrument need not to be horizontal.
Fig. 19
K Adjustment Screws
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7-6 Index Error
These inspection and adjustment are made after the inspection and ad-
justment of telescope level. Check that the bubbies in the plate level
and in the telescope level are positioned in the center and take a read-
ing of vertical circle. At this time, if the reading of vertical circle is ©,
no adjustment is necessary. if it is not o, removing standard cover at the
side of vertical circle, loosen clamp nut with adjustment pin and by ro-
tating vernier adjustment screw with adjustment pin, set the reading of
vertical circle to O and tighten clamp nut.
3
3
H
Fig. 18 | Adjustment Screw J Clamp Nut
7-7 Optical Plummet {Q.P.}
The line of sight of O.P. should coincide with the prologation line of
the center of vertical axis. So do inspect and confirm whether the opti-
cal plummet is adjusted correctly or not.
Inspection
1. Attach the instrument to the tripod and set it. Place on a ground a
sheet of white paper on which a cross fine is drawn below instru-
ment.
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1. Technical Data
Tetescope . . . .. . -—.anedaorere ree errect image
Magnification . . .. . . . ese eee. 28X
Clear objective aperture . . . ...e.omreno 1.6in 40mm
Field of view at 1,000f¢/m. . . . . ........ 24ft 24m
Shortest [+ using distance. .. . . . e... 5.3it 1.6m
Multiplication constant, .. . 224484050140 01 811 80 100
Additive constant. . . 1... 224 4020404 aer .D
Bubble sensitivities per 2mm run
Telescope level . . . . .. o nevar rare rece 40”
Plate level 1... 12021014 44104 4 24 44 6 1 8 4 41 400 ‚ 90”
Circular lewel. . . . . . 2 10410 41420404 410404 4 2 4 4 00 +20 10'
Horizontal circle . .. .. .. e. re. carrer exa. . 350
Graduation diameter {T-24B) . ......eÑo.. 4 .7in 120mm
Graduation diameter (GT-4B and GT-6B} . . . .4.3in 110mm
Vernier reading . . . 1 2 22 202 40404 5 4 0 4 04 4084 50 00 0 20°
Vertical circle
Graduation diameter (T-24B) . . . . .. ea 2.8in 70mm
Graduation diameter (GT-4B and GT-68) . . . .2.8in 70mm
Vernier reading . . 1,1. 22121005 +0 ae ae 1 4 8 1 8 04 6 . 1
Compass... 1.242 40404000 1 2 55 41 1 0040 Built in bar type
Weight
Instrument of T-74B ., 2.120202 44 4 4 442 0 0 9.9lbs 4.5kg
Instrument of GT-48.... 11214 2 28401 001 6 10.81bs 4 9kg
Instrument of GT-68......2 2244 04000 .10.81bs 4 9kg
Plastic carrying ase. . . . « « «+ « « кок + «0 a = 4.4165 2.0kg
-4-
2. Description
2-1 T-24B
Fig. 1
O Tetescope clamp screw
@ Focussing knob
© Circular bubble
© Horizontal upper drive screw
6) Horizontal upper clamp screw
Foot screw
© Optical sight
E) Objective tens
© Reticle illumination knob
D Compass clamp knob
MP Horizontal circle reading
eyepiece |B}
Adjustment
1. Point the telescope to the target board in the longer distance. Adjust
the reading by rotating the telescope drive screw 50 as to be the
same reading to the target board in the shorter distance.
2. Rotate the bubble adjustment nut (Fig. 17) with the adjusting pin
to center the bubble in the telescope level.
3. Repeat from inspection 4 and check that the adjustment is correct.
Fig. 17 H Adjustment Nuts
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7-5 Telescope Level
Inspection
1.
2.
Prepare two same plates and set up the instrument in the center of
two walls having a distance of 30 — 50 meters and level it,
Center the bubble in the telescope level with telescope drive screw
to set both walls on the line of sight alternately. Set a target board
on each wall so that reading on it appears at the same level. (Fig.
168A)
Move the instrument to a position 2 meters distance from a wall and
level it. (Fig. 16B)
Center the bubble in telescope level with telescope drive screw and
take a reading on each target. If the readings are the same, no adjust-
ment is necessary. if they do not coincide, adjustment is necessary.
Target
Fig. 16
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16
® Vertical circle
{8 Compass index line
(D Optical plummet
H Horizental lower clamp screw
(D Horizontal lower drive screw
{D Telescope level
@ Telescope eyepiece
{D Telescope drive screw
éD Plate level
@ Horizontal circle reading
eyepiece {A
€ Circle rotation ring
2-2 GT-4B and GT-6B не 30-50m 30-50m
O
ra .
© Ы Fig, 14
9 Adjustment
1. 1f point B and point C do not coincide, set up point D located 1/4
of length of line EC from point C toward point B.
10 2. Aemove adjusting cover of telescope eyepiece section. By rotating
3 two reticle adjusting screws which are horizontally positioned
among reticle adjusting screws with 4 pieces of pin hole by adjusting
3 pin (See Fig. 15.), adjust so that cross hairs sight point © correctly.
3. Repeat the inspection and check that adjustment is correct.
5 1
5 a
= FIL ua ut
E A ELT
Fig. 2 A В 45
MR
O Telescope clamp screw © Optical sight В,
@ Focussing knob O Objective lens +
© Circular bubble © Reticle illumination knob >
O Horizontat upper drive screw {D Compass clamp knob À
G Horizonta! upper clamp screw ® Horizontat circle reading J Fa
Q Foot screw eyepiece (B] Ae 197
Fig. 15 G Reticle Adjustment Screws
7-3 Circular Bubble
After finishing adjustment of plate level in section 7-2, the circular
bubble shouid now be in the center of its setting circle. If the bubble
is not in the center, turn the adjustment screws with screw driver ar
adjusting pin until the bubble shifts in the center. (See Fig. 13.)
Fig. 13 F Adjustment Screws
7-4 Horizontal Collimation Error
The error of horizontal line of sight is eliminated in all cases by obtain-
ing the average observation of telescope in normal and reversed posi-
tion. Besides particular cases, the adjustment should be avoided by
yourself. If necessary, the adjustment is made as follows.
1.
Make the point which is 30m — 50m away from the instrument and
is the same height with that of instrument. With telescope in normal
position, vertical line of cross hairs sights the point and call it
point À.
Slacken telescope clamp screw (1) and reverse telescope and sight
the point B on the opposite side of point À under the same con-
ditions of point À.
Loosen horizonta! upper clamp screw (5) with telescope reversed
and turn the alidade clockwise and sight point À again.
Loosen telescope clamp screw and return telescope 1o normal posi-
tion. Make a point which is sighted similar distance with point B
and call it point C.
tf point B and point C coincide, no adjustment is necessary.
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16
© Vertical circle reading eyepiece
(B Compass index line
{{ Optical plummet
GP Horizontal lower clamp screw
D Horizontal lower drive screw
{ Telescope level
20
21
27
O Telescope eyepiece
(D) Telescope drive screw
ED Plate level
€) Horizontal circle reading
eyepiece (A)
@ Circle rotation ring
3. Preparation for Measuring
3-1 Setting up the Instrument and the Tripod
Adjust the fength of tripod legs so as to be comfortably high for meas-
uring. Set the tripod by eye over the ground point and tread metal shoe
firmly into ground. if necessary, use plummet bob. Set the instrument
on the tripod plate and fix it with center screw. Looking through optical
plummet eyepiece (14), rotate foot screw {B) and tilt the instrument so
as to coincide the cross of optical plummet eyepiece with ground point,
By extending or retracting each leg of tripod, position the circular
bubble in the center of setting circle. At this time, the cross of optical
plummet is on the ground point.
TF
Fig. 3
=F
A Tripod Plate B Center Screw
3-2 Leveling up by Plate Level
At first, memorize that the bubble of plate level moves to the shift
direction of left thumb when turning the foot screws. If the sun shines
100 strongly, the instrument should be protected from direct ray by
sunshade and so forth, Procedures of leveling up by plate level is
follows.
1. Leosen horizontal upper clamp screw [5) or horizontal lower clamp
screw (15) and rotate the alidade [upper part of instrument) so as
that plate level (20) is parallel to the line joining any two foot
-g-
6-3 Eyepiece Sunglass
This is used for the sun or bright object observation and is fitted on
telescope eyepiece [18],
The color of sungtass is dark green and light green. Two different col-
oured sunglasses available.
7. Testing and Adjusting
7-1 Tripod
There should be no looseness between the various components of the
tripod in particular between wooden parts and metal parts. If necessary,
tighten screw of each part by driver or wrench.
7-2 Plats Level
Level up the instrument as described in section 3-2 in advance, If the
bubble will not remain centered for all positions of atidade, adjust as
follows.
1. After leveling up instrument as described in section 3-2 and turn the
alidade through 180°, See the position of the bubble.
2. With adjusting pin, by turning adjustment screw, bring the bubble
to a point halfway between moved point. {See Fig. 12.} And by
turning foot screw C, bring the bubble to the center.
3. 1f the bubble does not remain in the center by turning the alidade
for all direction, repeat from step 2 until the bubble remains cen-
tered for all positions of alidade.
Fig. 12 E Adjustment Nut
-18-
6-2 Diagonal Eyepiece
lt is used for zenith and observing in confined spaces and so on. It is
fitted on telescope eyepiece (18). When fitting diagonal eyepiece, turn
rotation ring of telescope eyepiece counterclockwise and remove the
eyepiece, Turn the rotation ring of diagonal eyepiece clockwise to
fit on.
The direction of diagonal eyepiece can be turned through 360°. When
look through telescope with diagonal eyepiece fitted on, such phencme-
non rarely happens that reticle cross hairs are visible moved up and
down or right and left. But this phenomenon is not related to the pre-
cision of instrument. If necessary, it can be adjusted by three adjusting
SCrews.
screws {6}, A and B. Center bubble by turning A and B foot screws
toward equal and opposite direction.
2. Turn the alidade through 80° in a clockwise and center the bubble
by remaining foot screw C.
Furthermore, turn the alidade in the same direction through every
90°. Repeat step 1 and step 2. As a result, the bubble should be
always centered for all direction of the alidade.
3. If the bubble cannot be positioned in the center, the adjustment of
plate level is required. (See p. 18 Chapter 7-2.)
* After leveling up by plate level, shift the instrument on the tripod
plate and reset centering if necessary. At this time, take care not to
rotate tribrach on tripod plate. If rotate it, the bubble positioned in the
center would shift.
* Shifting device is incorporated in GT-68. Therefore, GT-6B can be
moved easily without shifting the bubbtes.
3-3 Centering under Roof Point
Method 1
The instrument can be centered under plumb bob suspended from a
roof or ceiling by lining up the plumb bob with the center of reticle
illumination knob (9). The instrument is fitted on the tripod placed un-
der the tip of plumb bob already suspended from rocf or ceiling point.
Level up the instrument by method of Chapter 3-2, and with telescope
reversed, set it horizontal and set vertical circle to 0° correctly.
The instrument is now shifted over tripod ptate [do not turn foot plate!
so as that the center of reticle illumination knob exactly coincide the
tip of the plumb bob.
Fig.4 C Plumb Bob D Reticle Illumination Knob
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Method 2
From roof point or ceiling point, a plumb Боб is suspended, move the
roof point and ceiling point to the ground and set ground point there,
Set the instrument on the ground point moved from roof or ceiling
point by method of Chapter 3-1 and Chapter 3-2 and under the above
mentioned steps centering of instrument to the ceiling point has been
achieved.
4, Measuring
4-1 Focussing and Sighting
4-1-1 Reticle Cross Hairs
Take off objective cap on telescope and fit sunshade on it if required.
Point telescope to bright direction, Turn telescope eyepiece [18] in
a counterclockwise direction and pull out the eyepiece ring. Looking
through telescope, rotate the eyepiece ring in a clockwise direction un-
til cross hairs line is sharp and black. Try to be relaxed when you look
through the eyepiece. Because you try to concentrate too hard while
looking at cross hairs, you will become susceptible to parallax. This will
also preduce a strain on your eyes.
4-1-2 Target Image Focusing
Slacken horizontal lower clamp screw (15) and telescope clamp screw
{1}. Point telescope to target by optical sight {7). Tighten all clamp
screw {1}. Point telescope to target by optical sight {7}. Tighten all
clamp screws. Look through telescope eyepiece and turn focussing
knob {2} untit target is seen. By turning horizontal lower drive screw
(16) and telescope drive screw (19), set cross hairs to target. Turn
focussing knob until target is seen sharp or free from parallax. {even if
your eyes move right and left, cross line does not slip out target.) The
focussing marks comprise an infinity (=) and three triangular marks.
The tip of each triangle (Al shows the distance direction. Smaller
triangle indicates greater distance. The smailer mark indicates about
4m 113.3ft), The middle mark indicates about 7em [6.7ft). The biggest
triangular mark indicates about 1.6m [5.3it}.
4-1-3 Sighting
Turn horizontal lower drive screw (16) and telescope drive screw 119)
or turn horizontal upper the drive screw (4} and telescope drive screw
(19) until telescope sights the target correctly. It depends on kinds of
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6. Optional Accessories
6-1 Electric lHumination
This is used for the dark places such as night and underground work.
Electric illumination consists of lamp house and battery box in one set.
Lamp house holds connection cable for connecting with battery box.
The brightness of cross hairs can be adjusted by reticle illumination
knob {9}.
Fig. 10 Etectric IHumination
-16-
5, Care and Maintenance
Before removing the instrument from tripod, remove all accessories. Fit
cap on objective lens and locsen each clamp screw. Align two or three
small round yellow packing marks. Make telescope horizontat and
tighten all clamp screws. Wipe off dust and stain clearly with soft cloth
{if possible, bleaching better). If the instrument gets wet and moisture,
get rid of it with soft cloth. Until the instrument gets dry completely,
do not put it into the container. Please avoid to put the instrument into
container with wet and moisture condition. Leave accessories in a fixed
place of container exactly and take care for them not to shift in a con-
tainer. When closing the lid of container and have difficulty to close it,
the way of packing is different. At this time, re-leave the instrument in
container seeing picture.
Fig. 9
-15-
target whether single vertical hair splits or double hairs put into the
target.
The last turn of a drive screw should be clockwise. At the time of
measuring in a dark place, set illumination device on instrument (151
and adjust reticle itlumination knob until cross hairs are illuminated.
4-2 Circle Reading
4-2-1 Horizontal Circle
First, read off the circle graduation in 20° unit on the regular scale
indicated by the G line on the vernier sacle. (In Fig. 5, 72° plus two
20’ graduatiuon, i.e. 72°40")
Secondly, read off the reading on the vernier scale which is most
closely aligned with the regular scale. Un Fig. 5, 7° plus two 20" gradu-
ation, i.e. 7°40" .}
Add the reading of the two scales together to obtain the final reading.
{In Fig. 5, 72°40" + 7°40" = 72°47"40" }
280. 290
Fig. 5 Horizontal Circle 72% 47:40”
* When angle measurement of very high precision is required, read off
both A and B verniers and take the average as the final value.
-12-
4-2-2 Vertical Circle
Firstly, read off the circle graduation in 30" unit on the regular scale
indicated by the O fine on the vernier scale. {In Fig. GA, 16° 30": in Fig.
6B, 17730.)
Secondly, read along the regular scale (in the direction of higher num-
bers} and read off the reading on the vernier scale which is most closely
afigned with regular scale. {In Fig. 6A, 23"; in Fig. 6B, 17".)
Add the reading of the two together to obtain the final reading. (In Fig.
6A, 1653": in Fig. 6B, 12°47")
+
A x 2e a
0 Jo ;
0 20 30 | Mo Ÿ 20 10 0
[
I os
0. 20 10 0m 203% 30.20 45g 4p 20 3°
A B
Fig. 6 Vertical Circle
The vertical graduated circle is a 0 - 90 - 0 - 90” - 0 compass scale.
When the line of sight of the telescope is horizontal, the reading is 0,
Vertical circle
Fig. 7 Vertical Circle
4-3 Setting Horizontal Circle to Required Value
When setting horizontal circle to 0° or to required angle, the following
steps are made.
1.
Loosen each clamp screw and by turning circle rotation ring (20),
position the circle graduation of required angle to the position
which can be read by circle reading eyepiece (22).
-13-
{In case of GT-4B and GT-6B, position the circle number of re-
quired angle engraved on horizontal circle rotation ring close to
horizontal circle lupe.)
2. Tighten horizontal upper clamp screw and turn horizontal upper
drive screw. Set the vernier graduation reading to required reading.
4-4 Stadia Surveying
Using stadia fine having in cross hairs, distance measurement can be
done from the center of the instrument to the staff. When line of sight
Is horizontal, 100 multiple of @: staff interval put into by stadia line
Is horizontal distance.
When line of sight is inclined, the calculation is made as follows.
WET
Fig. 8
5 =1002 Cos? 8 {Should be Ih = Th}
S = Horizontal distance
2 =Reading difference of top and bottom stadia line readings
8 = Vertical angle
Ih = Instrument height
Th =Reading of line of sight
-14-
FOR PROPER OPERATION OF OUR SURVEYING INSTRUMENTS
Cur surveying instruments are so precise instruments that their quality
is highly delicate. Surveying instruments do not only work well but also
become of no value unless they are carefully handled and operated. To
let surveying instruments work efficiently and be of use for long time,
we would like you to read through this instruction book.
This instruction book is commonly supplied with three types of survey-
ing instruments, that is, T-24B, GT-48 and GT-6B. The specification of
туре СТ-48 is completely identical with that of type GT-68, but no
shifting device is incorporated in the former.
The only difference between the circle of GT4B and that of T-248 is
that the former is made of gfass and the latter is made of metal. There-
fore, this instruction book is written mainly about T-24B for you to
understand them easily but particular specification of GT-48 and
GT-68 is written respectively in this instruction book.
Storage
The instrument shouid be stored in a dry, dust proof room, which
does not have a big temperature range. When the instrument is stored
for a long time, it must be sometimes removed from its tightty closed
container and the air must be circulated freety around the instrument.
If the inside temperature of storage place in a room or in a car were
extremely different from outside temperature, that is, measuring piace,
the instrument must be exposed to outside temperature. The minutes
for the instrument to be exposed will be about one minute per one
degree temperature difference.
Transport
For a long journey, by rail or road, the instrument should be packed
using enough cushioned materials to prevent any hard knock or shock.
If possible, it's recommendable that the expert should pack the instru-
ment for a long journey. It will be advisable to cover insurance for more
expensive instrument during the trip, If you transfer the instrument by
your own car, it is not necessary to pack it but you had better leave it
on the seat and fix it lest it should be rnîled. 1f the instrument were in
trunk or on the carrier of the car, wrap it well in blankets and so forth
and fix it by some method so as to prevent any hard knock or shock,
-1-
MEMO
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