TM 9-1829A, April 1944
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2021-07-07
c.
Replace second gear:
Place frame and magnet assembly in vise (not too tightly) with opening for second
gear bushing on top. Lubricate gear teeth with small amount of No. 00 grease, O.D. Do not overlubricate.
Place tiny brass thrust washer over lower end of second gear and place in frame. Drive brass bushing into
place (fig. 93) allowing about 0.003 inch end play. Test for free turning.
Figure 93: Driving second gear bushing in place
d.
Test magnet strength to determine proper hair spring:
Place hair spring selector (408164) on frame and
magnet assembly. Place assembly on calibrating machine (fig. 94) and run master at 60 miles per hour
(chapter 13). The reading obtained from the hair spring selector can be converted to hair spring tension (in
degrees) by referring to “Hair Spring Chart” (par. 31 f) after determining pointer deflection (in degrees) at 60
miles per hour of speedometer being repaired (see following list). Select proper hair spring from kit (408082).
Figure 94: Magnet strengt tester (408164; on frame and magnet assembly) attached to calibrating machine (T-170645)