SkyTrak 6036 Service Manual - Manual (Page 159)

Section 9 Hydraulic System
Model 6036/6036T S/N 9B0500 thru 14833 9-9
Relieve hydraulic pressure before servicing any
hydraulic component. Escaping hydraulic fluid
under pressure can penetrate the skin causing
serious injury.
5. Start the engine. Extend and retract the boom
several times to purge the system of air.
6. Depress the accelerator to full throttle. Place
the joystick in the “extend” position and hold
until the extend cylinder has fully extended.
Continue holding the joystick in the “extend”
position until the pressure readings are taken.
7. Check the pressure gauge reading. It should
read 2850 ± 50 psi
(196,4 ± 3,4 bar). If not,
adjust the boom extend port relief valve, Fig.
9.3, 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 ± 2 Nm) 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. Extend and retract the boom
fully several times to purge the system of air.
11. Install the transmission cover after adjustment.
Boom Retract Port Relief Valve
1. Engage the park lock, place the travel select
lever in neutral, level the boom and stop the
engine.
2. Operate the hydraulic controls after the engine
has stopped to relieve any trapped pressure.
• Should any of the hydraulic lines going to
the extend cylinder fail, there will be a loss
of hydraulic system pressure to the cylin-
der.
Example: If there was a hydraulic line
failure in the pressurized retract line during
retracting, 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 retraction
preventing an elevated load from retracting
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 cartridge. In the event that
the counterbalance valve cartridge was disabled for
emergency boom lowering or any unauthorized
adjustments are ever made to this cartridge,
remove and replace the cartridge with a new part.
Failure to replace this cartridge with a new part may
alter the holding characteristics of the counterbal-
ance valve creating an unsafe condition for machine
operation.
b. Pressure Checks and Adjustments
Boom Extend Port Relief Valve
1. Engage the park lock, place the travel select
lever in neutral, level the boom 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.
9.5.
Warning
Warning
Relieve hydraulic pressure before servicing any
hydraulic component. Escaping hydraulic fluid
under pressure can penetrate the skin causing
serious injury.
Wait for the hydraulic fluid to cool before serv-
icing any hydraulic component. Hot hydraulic
fluid can cause severe burns.
Before starting the engine be sure all hydraulic
connections are tight and all tools are removed
from the forklift.
Warning
Warning
Warning
Wait for the hydraulic fluid to cool before servic-
ing any hydraulic component. Hot hydraulic
fluid can cause severe burns.