SECTION 4 - BASIC HYDRAULIC INFORMATION & SCHEMATICS
4-2
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5. With cylinder fully retracted, shut down engine and
carefully disconnect hydraulic hose from cylinder
extend port.
6. Activate engine and retract cylinder. Check extend
port for leakage.
7. If extend port leakage is less than 6-8 drops per min-
ute, carefully reconnect hose to extend port, than
activate cylinder through one complete cycle and
check for leaks. If leakage continues at a rate of 6-8
drops per minute or more, cylinder repairs must be
made.
Cylinders With Single Counterbalance Valve
OPERATE ALL FUNCTIONS FROM GROUND CONTROL STATION ONLY.
1. Using all applicable safety precautions, activate
hydraulic system.
2. Shut down hydraulic system and allow machine to sit
for 10-15 minutes. If machine is equipped with bang-
bang or proportional control valves, turn ignition
switch to on, move control switch or lever for appli-
cable cylinder in each direction, then turn ignition
switch to off. If machine is equipped with hydraulic
control valves, move control lever for applicable cyl-
inder in each direction. This is done to relieve pres-
sure in the hydraulic lines.
Carefully remove hydraulic hoses from appropriate
cylinder port block.
3. There will be initial weeping of hydraulic fluid, which
can be caught in a suitable container. After the initial
discharge, there should be no further leakage from
the ports. If leakage continues at a rate of 6-8 drops
per minute or more, the counterbalance valve is
defective and must be replaced.
4. To check piston seals, carefully remove the counter-
balance valve from the retract port. After initial dis-
charge, there should be no further leakage from the
ports. If leakage occurs at a rate of 6-8 drops per min-
ute or more, the piston seals are defective and must
be replaced.
5. If no repairs are necessary or when repairs have been
made, replace counterbalance valve and carefully
connect hydraulic hoses to cylinder port block.
6. If used, remove lifting device supporting platform or
release and stow safety prop, activate hydraulic sys-
tem and run cylinder through one complete cycle to
check for leaks.
4.4
OSCILLATING AXLE - LOCKOUT CYLINDER TEST
(IF EQUIPPED)
LOCKOUT CYLINDER SYSTEM TEST MUST BE PERFORMED QUARTERLY,
ANY TIME A SYSTEM COMPONENT IS REPLACED, OR WHEN IMPROPER
SYSTEM OPERATION IS SUSPECTED.
NOTE:
Ensure platform is fully lowered prior to beginning
lockout cylinder test, and that the surface used to
approach the ramp is flat and level.
Left Side Wheel Test
1. Place a 4 inch (10.16 cm) high block with ascension
ramp in front of left wheel of the oscillating axle.
2. From platform control station, select LOW drive
speed.
3. Set the DRIVE control switch into position and care-
fully drive the machine up ascension ramp until left
oscillating axle wheel is on top of block.
4. Verify the axle oscillates to maintain contact with the
ground/ramp. (All four wheels on the ground).
5. Raise machine platform above stowed position to
drive cutout height, approximately 6 to 9 ft. (2 to 3m)
for the 330LRT and 430LRT.
6. Carefully drive the machine back off the block and
ramp.
7. Have an assistant check to see that the left oscillating
axle wheel that was on the block is in position on the
ground. The axle should oscillate so that all four
wheels maintain contact with the ground.
8. In the current position (platform raised and all four
tires on flat and level surface), carefully drive
machine up the ramp block again.
9. Have an assistant check to verify that the axle did not
oscillate and remained locked (one wheel is off of the
ground).
10. Carefully drive the machine back off the block and
ramp.
11. Lower the machine platform; the lockout cylinder
should then release and allow wheel to rest on the
ground. It may be necessary to activate DRIVE to
release cylinders.
12. If the lockout cylinders do not function properly,
have qualified personnel correct the malfunction
prior to any further operation.
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