TM 5-5420-234-14&P
5-2. DIRECT SUPPORT TROUBLESHOOTING (continued).
4.
MAIN FRAME DOES NOT LOAD (continued).
COUNTERBALANCE VALVE TEST
WARNING
The main frame cylinders may be under hydrau-
lic pressure. Steps 1 thru 4 must be performed to
relieve hydraulic pressure, before removing coun-
terbalance valves from main frame manifold.
Failure to comply with this warning may result in
damage to equipment and injury to personnel.
(1)
Turn engine switch to ON and light control switch to
STOP LIGHT position.
(2)
Turn LHS MODE SELECT switch to AUTO position.
NOTE
Perform Step 3 only if main frame and hook arm are
not in the stowed position.
MAIN FRAME
PORT VB
MANIFOLD
(3)
Hold a piece of metal over the main frame down and
hook arm down proximity switches until main frame
reaches fully retracted or fully extended position.
(4)
Turn off engine and light control switches after a
minimum of three minutes.
NOTE
Oil will drip from main frame manifold when
counterbalance valve is removed.
(5)
Remove counterbalance valve from right main frame
PORT VA
manifold port VA.
(6)
Remove counterbalance valve from right main frame
manifold port VB and install in port VA.
(7)
Install remaining counterbalance valve in right main
frame manifold port VB.
COUNTERBALANCE
(8)
Start engine and engage the PTO.
VALVE
(9)
Turn the light control switch to the STOP LIGHT
position. Place LHS MODE SELECT switch in the
HOOK ARM ONLY (manual mode) position.
(10) Attempt to load the main frame using the remote
control or cab controls. Note the operation of the
main frame.
(11) Shut off engine and turn light control switch to OFF
position.
(12) If the main frame now loads properly, the
counterbalance valve installed in the right manifold
port VA is faulty. If the main frame still does not
load, the counterbalance valve in the left manifold
port VB is faulty.
5-27
