SkyTrak 6036 Service Manual - Manual (Page 116)

Section 9. Hydraulic System
9-3 Model 6036 S/N 9B0499 and Before
ing, the counterbalance valve would lose pilot
pressure closing off flow returning to the
reservoir. The oil in the base end of the
cylinder would then be trapped, which would
immediately stop boom lowering and prevent
an elevated load from falling to the ground
uncontrolled. The load can be lowered safely
to the ground by following the “Emergency
Boom Lowering” procedures in your Owners/
Operators Manual.
IMPORTANT: DO NOT attempt to reset the
counterbalance valve cartridges. In the event that
the counterbalance valve cartridges were disabled
for emergency boom lowering or any unauthorized
adjustments are ever made to these cartridges,
remove and replace both cartridges with new
parts. Failure to replace these cartridges with new
parts may alter the holding characteristics of the
counterbalance valves creating an unsafe condi-
tion for machine operation.
b. Pressure Checks and Adjustments
Main Relief Valve
1. Engage the park lock, place the travel select
lever in neutral, and stop the engine.
2. Operate the hydraulic controls after the
engine has stopped to relieve any trapped
pressure.
3. Remove the transmission cover from the
frame.
4. Install a tee and pressure gauge capable of
measuring 0 - 4000 psi (275,6 bar) in the
tandem pump outlet of the 30 gpm section,
Fig. 9.1.
5. Start the engine. Raise and lower the boom
fully several times to purge the system of air.
6. Depress the accelerator to full throttle. Place
the joystick in the “lower” position and hold
until the hoist cylinders have fully retracted.
Continue holding the joystick in the “lower”
position until the pressure readings are taken.
7. Check the pressure gauge reading. It should
read 3,000 ± 50 psi (206,7 ± 3,4 bar). If not,
adjust the main relief valve, Fig. 9.2, by turning
the adjustment screw clockwise to increase
pressure or counterclockwise to decrease
pressure. Torque nuts on relief valve to 10 ±
1.5 lb-ft (13,5 ± 2 N m) after adjustment.
8. Stop the engine. Operate the hydraulic
controls after the engine has stopped to
relieve any trapped pressure.
9. Remove the pressure gauge and tee from the
tandem pump and reconnect the hydraulic
line.
10. Start the engine. Raise and lower the boom
fully several times to purge the system of air.
11. Install the transmission cover after adjustment.
Warning !
Warning !
Wait for the hydraulic fluid to cool before servic-
ing any hydraulic component. Hot hydraulic fluid
can cause severe burns.
Warning !
Before starting the engine be sure all hydraulic
connections are tight and all tools are removed
from the forklift.
Relieve hydraulic pressure before servicing any
hydraulic component. Escaping hydraulic fluid
under pressure can penetrate the skin causing
serious injury.