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REV B
Section 4 • Repair Procedures
June 2005
4 - 36
TMZ-34/19
Part No. 52075
6-2
Valve Adjustments -
Hydraulic Power Unit
How to
Adjust the System Relief Valve
1 Connect a 0 to 5000 psi / 0 to 350 bar pressure
gauge to the test port on the hydraulic power
unit.
2 Turn the key switch to ground controls and pull
out the red Emergency Stop button to the on
position at both the ground and platform
controls.
3 Fully raise the primary boom.
4 Press and hold the high speed function enable
button and press and hold the primary boom up
button and observe the pressure reading on the
pressure gauge. Turn the machine off.
5 Hold the relief valve adjusting screw and loosen
the lock nut.
6 Adjust the relief valve screw. Turn it clockwise
to increase the pressure or counterclockwise to
decrease the pressure. Refer to Section 2,
Specifications.
Tip-over hazard. Do not adjust the
relief valve higher than specified.
7 Hold the relief valve screw and tighten the lock
nut. Be sure the relief valve screw does not
turn.
8 Repeat steps 2 through 4 to confirm the relief
valve pressure.
9 Bleed the hydraulic system by raising the
platform to full height. If the pump cavitates or
platform fails to reach full height, add hydraulic
oil until the pump is functioning correctly. Do not
overfill the hydraulic tank.
Component damage hazard. Do
not continue to operate the
machine if the hydraulic pump is
cavitating.
HYDRAULIC POWER UNIT
a
c
d
e
f
b
a
hydraulic tank
b
test port
c
pump motor
d
pump
e
lock nut
f
relief valve adjusting screw
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