Service Manual Instruction Manual

SECTION 5 - HYDRAULICS
3121616 – JLG Lift – 5-71
5.9 PRESSURE SETTING PROCEDURES
COLD TEMPERATURES HAVE A SIGNIFICANT IMPACT ON PRESSURE READINGS.
JLG INDUSTRIES, INC. RECOMMENDS OPERATING THE MACHINE UNTIL THE
HYDRAULIC SYSTEM HAS WARMED TO NORMAL OPERATING TEMPERATURES
PRIOR TO CHECKING PRESSURES. JLG ALSO RECOMMENDS USING A CALI-
BRATED GAUGE. PRESSURE READINGS ARE ACCEPTABLE IF WITHIN +/- 5% OF
SPECIFIED PRESSURES.
Main Relief, Steer, Swing, and Lift Down
1. Install pressure gauge at quick disconnect on port MP
on main valve.
2. With aid of an assistant, activate telescope in.
3. Monitor pressure gauge and adjust main relief valve to
3000 PSI (206.85 Bar).
4. With the aid of an assistant, activate steer left.
5. Monitoring pressure gauge and adjust steer left relief
valve to 1800 PSI (124.1 Bar).
6. With aid of an assistant, activate steer right.
7. Monitor pressure gauge and adjust steer right relief
valve to 1800 PSI (124.1 Bar).
8. With aid of an assistant, activate swing left or right.
9. Monitor pressure gauge and adjust swing relief valve to
1700 PSI (117.2 Bar).
10. With aid of an assistant, activate lift down.
11. Monitoring pressure gauge and adjust lift down relief
valve to 1200 PSI (82.7 Bar).
Platform Level
1. Install pressure gauge at quick disconnect on port M3
on main valve.
2. With aid of an assistant, activate platform level forward.
3. While monitoring pressure gauge, adjust platform level
relief to 2800 PSI (193.06 Bar).
4. Install pressure gauge at quick disconnect on port M4
on main valve.
5. With aid of an assistant, activate platform level back-
ward.
6. Monitor pressure gauge and adjust platform level relief
valve to 1800 PSI (124.11 Bar).
Articulating Jib Boom (If Equipped)
1. Install pressure gauge at quick disconnect on articulat-
ing valve.
2. With aid of an assistant, activate articulating jib up.
3. Monitor pressure gauge and adjust articulating jib up
relief valve to 1500 PSI (103 Bar).
4. With aid of an assistant, activate articulating jib down.
5. Monitor pressure gauge and adjust activate articulating
jib down relief valve to 1200 PSI (83 Bar).
Figure 5-131. Articulating Jib Boom Pressure Adjustment
4 Wheel Steer (If Equipped)
1. Activate "2 wheel steer" at platform console using steer
select switch.
2. Install pressure gauge in port MP on main control valve.
3. With aid of an assistant, activate steer left and right.
Adjust front steer relief valve to 2500 PSI (172.4 Bar). This
pressure only affects the front axle.
4. Activate “crab” or “coordinated” steer at platform con-
sole using steer select switch
5. Disconnect wire DIN connectors on front steer valve at
main control valve block. When steer is activated only
rear steer will work.
6. Install pressure gauge in port MP on main control valve.
7. With aid of an assistant, activate steer left and right.
Adjust rear steer relief valve to 2500 PSI (172.4 Bar). 2500
PSI (172.4 Bar) at valve bank will give 2000PSI (137.9 Bar)
at cylinders.
8. Reconnect front steer DIN connectors at valve bank.
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