TM 9-1829A, April 1944
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2021-07-07
44. Assembly and calibration
a.
Replace oil wick and plug:
Saturate oil wick in watch and clock oil and place in frame. Using punch, tap oil
wick into place (fig. 67).
b.
Replace bonnet assembly:
Place bonnet springs in recesses around corner posts of frame (fig. 116). (All new
frames have an iron keeper on the magnet which must be removed before the bonnet is put on.) Place bonnet
assembly on springs. Line up reset stem holes in frame and bonnet, taking care not to dislodge springs. Make
sure that hair spring regulator arm is in correct position (fig. 114) and that hair spring is properly adjusted
(par. 43 b). Insert bonnet screws (fig. 115) and tighten.
Figure 116: Frame, second gear and magnet assembly
c.
Replace reset shaft, third gear, odometers, and dial supports
(fig. 114): Place reset shaft through hole in
frame. Place small amount of No. 00 grease, O.D. on teeth and bearing surfaces of ‘third gear and place in
frame. Place total odometer in frame in same position as before removal, so that mileage reading will be the
same as before. If new odometer is installed or if old odometer has been turned back to zero, place in frame
with zeros on top. Place reset spring, reset gear, and drive gear on trip odometer shaft and place assembly in
frame. Place dial supports in position over locating pins making sure that upper end of third gear fits in hole
in right-hand support and that hair spring regulator arm is above left support. Stake locating pins which
protrude through the plate. If both sets of pins have been used, use four screws (Waltham No. 6161) to fasten
dial supports to the frame. Test for free turning (par. 4 b). Test odometer reset mechanism.
d.
Replace dial and pointer:
Attach dial to supports with two screws. Start pointer on staff at 40-mile mark
and turn to zero while pressing on staff with thumb.
e.
Calibrate:
Place unit on calibrating machine, hold in approximately the same position as it will be on vehicle,
run master head on machine at 10 miles per hour and, by moving hair spring regulator on speedometer up (if
fast) or down (if slow) make it read the same as the master head. (This must be done before testing at other
speeds.) Then run master at 60 miles per hour and, using special tool (T-189787 - STS 10878), loosen the
two bonnet adjusting screws evenly (by turning tool clockwise) until the speedometer indicates 60 miles per
hour (fig. 117). Then check at 30 and 10 miles per hour. Bonnet adjusting screws should not be turned out
more than 1
1
/
2
turns. In exceptional cases the speedometer reading may be too high, even though adjusting
screws are turned out 1
1
/
2
turns. In such cases cut
1
/
2
coil from hair spring.