5-2. DIRECT SUPPORT TROUBLESHOOTING (continued).
MAIN FRAME DOES NOT UNLOAD (continued).
MAIN FRAME UNLOAD PRESSURE TEST
The LHS hydraulic system operates at
oil pressures up to 3,625 psi (24,994
kPa). Never disconnect any hydraulic
line or fitting without first dropping pres-
sure to zero. Failure to comply with this
warning may result in serious injury or
death to personnel.
(1) Remove plug and O-ring from port TPMB on
main hydraulic block assembly.
(2) Install hose adapter, hose, and pressure
gage on main hydraulic block assembly.
(3) Start engine and engage the PTO.
(4) Turn the light control switch to the STOP
LIGHT position. Place LHS MODE SELECT
switch in the HOOK ARM ONLY (manual
(5) Attempt to unload the main frame using the
remote control or cab controls.
Fully extending or retracting hydraulic
cylinders will put the hydraulic system
into relief. This should be limited to 10
seconds. Failure to comply with this
caution may result in damage to equip-
During an empty unload cycle, the hy-
draulic pressure will read approximately
1,000 psi until the main frame hydraulic
cylinders are fully extended. Full relief
pressure of 3,100 to 3,300 psi will be
reached at full extension of the hydrau-
(6) Observe the readings on the pressure gage
(7) Shut off engine and turn off light control
(8) Remove hose adapter, hose, and pressure
gage from main hydraulic block assembly.
(9) Install plug and O-ring in port TPMB on main
hydraulic block assembly.