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 348 of 836
TM 9-2320-272-24-4
5-50. CENTER SUPPORT MAINTENANCE (Contd)
1.
2.
3.
4.
5.
6.
7.
8.
Remove filter screen (14) and seal ring (13) from center support (10). Discard filter screen (14) and
seal ring (13).
NOTE
The second and third clutch pistons are disassembled the
same way. This procedure covers the second clutch piston.
Remove second clutch piston (11) from center support (10).
Remove inner seal ring (5) and outer seal ring (6) from second clutch piston (11). Discard seal
rings (5) and (6).
Remove four self-locking retainers (1) from pins (12) on second clutch piston (11). Discard self-locking
retainers (1).
Remove retainer (2) and twenty springs (3) from second clutch piston (11).
Remove two step-joint seal rings (7) from center support (10). Discard step-joint seal rings (7).
NOTE
Bushing is removed only if it fails inspection (task c).
Mark location of bushing notch on center support for
reassembly.
Replace checkball if bushing is replaced.
Press bushing (8) out of center support (10) with arbor press and mandrel. Discard bushing (8).
Remove checkball (9) from center support (10). Discard checkball (9).
1.
2.
3.
4.
5.
6.
For general cleaning instructions, refer to para. 2-14.
For general inspection instructions, refer to para. 2-15.
Inspect center support (10) cavities for obstruction or foreign material. Remove obstruction or
foreign material.
Measure depth of anchor bolt hole in center support (10). If hole is not 1.610 in. (40.89 mm) deep,
rework center support (10) as follows:
a. Drill 1.610 in. (40.89 mm) hole in center support (10).
b. Counterbore 0.469 in. (11.91 mm) diameter 0.66-0.70 in. (16.8-17.8 mm) deep.
c. Tap hole using 3/8 in. (9.53 mm) tap UNC2B min. Full thread to depth of dim. A.
Inspect four pins (12) on each piston (4) and (11) for bends and breaks. If any pin (12) is damaged,
replace piston (4) or (11).
Inspect all springs (3) for discoloration due to overheating. If discoloration is present, discard
springs (3).
5-342
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