TM 9-1829A, April 1944
17/100
2021-07-07
6. Disassembly.
a.
Remove bezel:
Remove bezel by carefully cutting with side cutters so case and gaskets will not be cut, and
glass will not be broken. Lift the glass, gaskets, and glass container from the case. On front reset
speedometers, first pull off rubber tip and then remove spring and washer.
b.
Remove case:
Remove two screws and lock washers from back of case and lift out frame and mechanism
assembly. Dustproof sealing sometimes causes frame to stick to case.
Note: If instrument has reset odometer,
first remove the screw and knob from reset shaft.
c.
Remove pointer and dial:
Grasp the pointer hub between the thumb and forefinger, and twist gently in a
direction reverse from normal pointer travel. Lift the pointer off the shaft while performing the twisting
operation. Use a small screwdriver to remove the two dial screws, and lift dial off frame.
Note: It is important
to use a screwdriver that fits the dial screw slots because a poor-fitting screwdriver will often slip and mar
the dial or break off luminous paint.
d.
Remove front jewel and bracket:
Remove two bracket retaining screws and lift off jewel and bracket. Note:
Look for and salvage the speed cup staff thrust washer. This washer may stick to jewel in bracket, or on step
of speed cup staff. On front reset speedometers, the reset shaft should be removed from the jewel bracket.
e.
Remove odometer-total and trip not of the quick-reset type:
Remove the retainer from the left end of the
odometer shaft. To do this, raise clip until enlarged portion of clip slot is over the odometer shaft, then push
the shaft into the frame and lift the clip upward. Push the odometer shaft out with short piece of wire or rod.
Centralize the short rod in the frame and lift the odometer out as a unit.
f.
Remove odometer-quick-reset trip type
(fig. 18): Remove the retainer from the left end of the trip odometer
shaft, tip the speedometer slightly to the left, and permit the shaft bushing and spacer to slide off the shaft.
Lift out the odometer by first moving it to the left, and then remove thrust washer, trip drive gear, and drive
gear spring.
Note: Do not remove the retainer which is clipped to the shaft at the left of quick-reset figure
wheels. Service the quick-reset odometer and shaft only as an assembly.
Figure 18: Quick reset trip odometer removed from frame
g.
Remove reset shaft:
Remove the solid reset shaft and gear assembly from the main frame by lifting the lower
coil of the reset shaft spring from the groove around the shaft. Remove reset knob if used. Lift reset shaft out
of frame. Flexible reset shafts are serviced as part of the main frame.
h.
Remove third gear:
Lift out of frame.
i.
Remove field plate and speed cup:
With a small pair of pliers, remove tapered pin securing end of hair
spring in regulator arm of field plate. Push hair spring end out of regulator arm hole. Remove two screws
holding field plate in position. Lift the two parts out successively, first the field plate, making sure the hair
spring is not caught, then the speed cup.
Note: AC speed cups are serviced as an assembly of the cup, staff
and hair spring. Do not disassemble.
j.
Remove second gear
(fig. 19): Use punch to drive out the second gear, bushing, and thrust washer. Drive
from the end opposite to the inserted bushing. Remove thrust washer which usually sticks to side of main
frame.
Note: Use care in driving out the second gear to avoid marring bearing hole in frame.