TM-9-2320-272-24-3
TRUCK, 5-TON, 6X6, M939, M939A1, AND M939A2 SERIES TRUCKS (DIESEL)
TECHNICAL MANUAL; UNIT, DIRECT SUPPORT, AND GENERAL SUPPORT MAINTENANCE MANUAL; VOLUME 3 OF 4
JUNE 1998
TM-9-2320-272-24-3 - Page 52 of 799
TM 9-2320-272-24-3
4-52. AIR COMPRESSOR MAINTENANCE (Contd)
8.
9.
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11.
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15.
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17.
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19.
20.
21.
22.
Remove four screws (l), lockwashers (2), washers (3) compressor head cover (4) gasket (5),
compressor head (6), and gasket (7) from compressor crankcase (16). Discard lockwashers (2) and
gaskets (5) and (7).
Press exhaust valve seat (33) from hole (34) on bottom of compressor head (6).
Remove O-ring (32), exhaust valve seat (33), seal (31). exhaust valve (30), exhaust valve spring (29),
and wear plate (28) from compressor head (6). Discard O-ring (32), exhaust valve seat (33), seal (31),
exhaust valve (30), exhaust valve spring (29), and wear plate (28).
Remove two screw-assembled lockwashers (17), four screws (19), and washers (18) from compressor
crankcase (16) and support (25). Discard screw-assembled lockwashers (17).
Use care when removing crankshaft from connecting rod to avoid
damage.
Rotate crankshaft (27) 90 degrees before or after top dead center of piston (14) for ease of removal.
Remove support (25), crankshaft (27), and gasket (26) from compressor crankcase (16). Discard
gasket (26).
Install crankshaft (27) and support (25) in soft-jawed vise.
Remove screw (24) and washer (23) from drive gear (22) and crankshaft (27).
Compressor drive gear is drilled and tapped for metric threads.
Using gear puller, remove drive gear (22) from crankshaft (27).
Using arbor press, remove spacer (21), thrust washer (20), and crankshaft (27) from support (25).
Remove support (25) from vise.
Remove piston (14) and connecting rod (15) from compressor crankcase (16).
Remove top (9) and intermediate (10) compression rings from piston (14). Discard compression
rings (9) and (10).
Do not drive piston pin from bore. Damage to piston may result.
It may be necessary to heat piston in hot water to remove piston
pin.
Remove two oil rings (11) and oil ring expander (12) from piston (14). Discard oil rings (11) and
oil ring expander (12).
Remove two retaining rings (8), piston pin (13), and connecting rod (15) from piston (14).
4-316
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