TM-9-2320-272-24-4
TRUCK, 5-TON, 6X6, M939, M939A1, AND M939A2 SERIES TRUCKS (DIESEL)
TECHNICAL MANUAL; UNIT, DIRECT SUPPORT, AND GENERAL SUPPORT MAINTENANCE MANUAL; VOLUME 4 OF 4
JUNE 1998
TM-9-2320-272-24-4 - Page 446 of 836
TM 9-2320-272-24-4
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16.
NOTE
Replace entire differential gear assembly if helical ring gear,
spider, spider gears, bevel gears, or thrust washer fails inspection.
Inspect two bearings (2) and races (1) (TM 9-214). Replace bearing (2) and race (1) as a set
if either part fails inspection.
Inspect two differential gear housings (4) for chips, burrs, cracks, pitting, scoring, and breaks. For
repair of minor damage, refer to para. 2-16. Replace entire differential gear assembly if differential
gear housings (4) are damaged.
Measure inside diameter of bearing races (5) and outside diameter of differential gear housing
hubs (3). The difference between measurements (press fit) must be within 0.0015-0.0035 in.
(0.0381-0.0889 mm). Replace entire differential gear assembly if press fit is not within limits.
Inspect four thrust washers (12), bevel spider gears (ll), two thrust washers (6), bevel side gears (7),
spider (9), and helical ring gear (8) for cracks, breaks, chips, burrs, scoring, and pitting. For repair of
minor damage, refer to para. 2-16. Replace entire differential gear assembly if any part fails
inspection.
Measure outside diameter of four spider arms (10). Measurement should be 1.122-1.123 in.
(28.50-28.52 mm). Replace entire differential gear assembly if spider arm(s) (10) are not within
limits.
Measure inside diameter of four bevel spider gears (11). Measurement should be 1.128-1.130 in.
(28.65-28.70 mm). Replace entire differential gear assembly if bevel spider gear(s) (11) are not
within limits.
Inspect two bearings (19) and races (18) (TM 9-214). Replace bearing (19) and race (18) as
a set if either part fails inspection.
Inspect bevel ring gear (13), sleeve (15), spacer (16), and helical pinion gear (17) for chips, breaks,
cracks, burrs, nicks, and scores. For repair of minor damage, refer to para. 2-16. Replace bevel ring
gear (13), sleeve (15), spacer (16), and helical pinion gear (17) if damaged.
Measure inside diameter of bearing races (20) and outside diameter of pinion gear shaft (21). The
difference between measurements (press fit) must be within 0.0000-0.0015 in. (0.0000-0.0381 mm).
Replace helical pinion gear (17) and bearings(s) (19) if press fit is not within limits.
Inspect bearing (14) (TM 9-214). Replace bearing (14) if damaged.
Measure outside diameter of bevel ring gear (13) and inside diameter of race on bearing (14). The
difference between measurements (press fit) must be within 0.0006-0.0011 in. (0.015-0.028 mm).
Replace bevel ring gear (13) and bearing (14) if press fit is not within limits.
Measure outside diameter of bearing (14) and inside diameter of spacer (15). The difference between
measurements (press fit) must be within 0.0030-0.0058 in. (0.076-0.147 mm). Replace bearing (14)
and sleeve (15) if press fit is not within limits.
5-440
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