TM 9-2320-279-34-3
M977, M985, and M984E1 Crane Maintenance Instructions (Cont)
b. Test Procedure.
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
(10)
(11)
Close bleeder valves (9) and (11).
Extend and retract cylinder (1) three to five times while checking
Extend cylinder (1) full stroke and maintain pressure of 2500 psi (1
minimum of one minute while checking for leaks.
Relieve pressure and uncouple quick-disconnect (4).
NOTE
With piston port blocked, pressurizing rod side will cause an ini
the cylinder due to the compression of air within the system.
Apply 2000 psi (13.8 mPa) to hose (8).
for leakage at rod seal (13).
7.2 mPa) on hose (5) for
tial retraction of
Slowly open bleeder valve (9) to retract cylinder (1) approximately 1 inch (25.4 mm).
NOTE
If cylinder extends while applying pressure to the rod side port, cylinder has an
internal leak at the piston seal and/or holding valve.
Close bleeder valve (9) and maintain 2000 psi (13.8 mPa) to hose (8) while checking for leaks and
observing if cylinder (1) extends.
Slowly open bleeder valve (9) to retract cylinder (1) to midpoint of stroke and repeat Step 7.
Slowly open bleeder valve (9) to fully retract cylinder (1).
Relieve pressure and disconnect cylinder (1).
Plug or cap all ports.
c. Follow-on Maintenance. If cylinder leaked, or extended while pressurizing the rod side port,
repair cylinder before using.
END OF TASK
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