
TM 9-1829A, April 1944
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2021-07-07
d.
Magnet (including first gear):
If magnet shaft shows excessive wear, if squared connection for cable tip is
damaged, or if first gear is worn, magnet and shaft must be replaced. Care must be taken so that magnet does
not come in contact with tools, metal objects, etc., as this will cause magnet to lose its strength.
e.
Hair spring:
The hair spring should lie perfectly flat, and coils should be evenly spaced and not touch each
other at any point. If hair spring is bent out of shape and cannot be readily straightened with tweezers, discard.
f.
Odometers:
Wipe dials clean with rag. Do not wash in drycleaning solvent, as lubricant will be removed.
Inspect for free movement of figure wheels and see that gear teeth are intact. If defective, discard complete
assembly.
g.
Main frame:
Inspect bearing surface (for magnet shaft) for wear or scoring. Be sure all threads are in good
condition, and that field plate is in place. If intermediate gear has not been removed inspect for excessive
looseness, and for worn or damaged teeth.
h.
Second and third gears:
Inspect for excessive wear and broken teeth. If defective, discard.
31. Assembly and calibration
a.
Replace odometer intermediate gear assembly:
Place washer over odometer drive gear shaft and place
shaft through frame with drive gear on inside. Place another washer over shaft (outside of frame). Rest end
of drive gear shaft on anvil of staking fixture (T-178717 Det. 4) held in vise. Using female punch, drive spur
gear on shaft as far as it will go. Using staking tool (T-178717 Det. 3) stake outside end of drive gear shaft
securely (fig. 64). Check to see that gear turns freely.
b.
Replace magnet
(including first gear): Place front thrust washer over magnet shaft. Lubricate first gear (on
magnet shaft) with small amount of No. 00 grease O.D. Lubricate shaft with watch and clock oil and place in
frame. Place rear thrust washer and magnet shaft collar over end of shaft. Using magnet assembly fixture (T-
170666 with Det. 1), tighten down (fig. 65) until collar is pressed all the way onto shaft.
Caution: Care must
be taken when using fixture to make sure that it does not come in contact with steel portion of magnet, causing
it to be weakened.
Figure 65: Pressing collar on magnet shaft, using fixture (T-170666 with Det. 1)
Using fixture (T-170666 with Det. 6) flare end of magnet shaft (fig. 66). Allow about 0.003 inch end play
(barely perceptible) in magnet shaft. Check to see that magnet turns freely.
Figure 66: Flaring magnet shaft, using fixture (T-170666 with Det. 6)