TM 9-1829A, April 1944
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2021-07-07
Figure 28: Removing second gear
Figure 29: Removing magnet shaft collar, using dismantling wrench (T-170654)
12. Cleaning, inspection, and repair of parts
a.
General cleaning:
After speedometer has been disassembled, thoroughly clean frame and intermediate gear,
second gear, third gear, speed cup, field plate, hair spring, screws, metal washers, and brackets with brush
and dry-cleaning solvent. In the cleaning process remove every trace of grease, dust or foreign matter of any
kind. Only a thoroughly clean part will reveal defects such as wear, small cracks, and dents which might
easily be hidden from view. After these parts have been cleaned, dry with compressed air, being careful not
to damage hair spring. Wipe other parts clean with a cloth.
b.
Inspection and repair:
(1)
Case:
Inspect for dents, out-of-round condition, or for being damaged in any way.
(2)
Main frame:
Inspect for dents of any kind, such as small cracks, or rough bearing surface; be sure all
threads are in good condition; if necessary, insert screws to test. Check for being out of line and make
sure locating pins are in good condition.
(3)
Magnet:
Inspect alinement and discard magnet if bent. Be sure both magnet bar and magnet clips are
firm and solid, and that the gear teeth are in good condition. Install magnet in frame, and check amount
of stock on end of magnet shaft to make sure there is enough to flare over when installing shaft and collar
in main frame. Be sure rear jewel is clean.
(4)
Gears:
Inspect for rough, worn or chipped teeth. Inspect bearing surfaces for roughness and excessive
wear, and check for bent shaft.
(5)
Field plate:
Make sure plate is smooth both inside and outside, and that it seats firmly on main frame
without touching or interfering with speed cup.
(6)
Speed cup:
Lay speed cup staff on edge of smooth surface with large cup part extending over edge, and
roll staff back and forth to detect a bent shaft. If staff is bent, install new speed cup. Examine lower end
of speed cup staff, being sure it is not bent or broken.