Adjustments - JLG 1850SJ Service And Maintenance Manual

SECTION 5 - BASIC HYDRAULIC INFORMATION & HYDRAULIC SCHEMATICS

Adjustments

CONTAMINATION CAN DAMAGE INTERNAL COMPONENTS AND VOID YOUR
WARRANTY. TAKE PRECAUTIONS TO ENSURE SYSTEM CLEANLINESS WHEN
REMOVING AND REINSTALLING SYSTEM LINES
1. Thoroughly clean the outside of the pump.
2. If removing the pump, tag each hydraulic line. When you
disconnect hydraulic lines, cap them and plug each
open port to prevent contamination.
3. Ensure the surrounding area is clean and free of contam-
inants like dirt and grime.
4. Inspect the system for contamination.
5. Check the hydraulic fluid for signs of contamination: oil
discoloration, foam in the oil, sludge, or metal particles.
6. If there are signs of contamination in the hydraulic fluid,
replace all filters and drain the hydraulic system. Flush
the lines and refill the reservoir with the correct filtered
hydraulic fluid.
7. Before reinstalling the pump, test for leaks.
CHARGE PRESSURE RELIEF VALVE.
1. Install a 50 bar [1000 psi] pressure gauge in charge pres-
sure gauge port M3. Install a 10 bar [100 psi] gauge at
case pressure port L1, L2, or L3. Operate the system with
the pump in neutral (zero displacement) when measur-
ing charge pressure.
2. The table below shows the acceptable pump charge
pressure range for some nominal charge relief valve set-
tings (refer to model code located on serial number
plate). These pressures assume 1800 min-1 (rpm) pump
speed and a reservoir temperature of 50°C [120°F], and
are referenced to case pressure.
NOTE: Listed pressures assume a pump speed of 1800 min-1 (rpm)
and charge flow of 26.5 l/min [7 US gal/min]. At higher
5-136
Locknut
19 mm
12 N•m
[9 lbf•ft]
Adjusting screw
5 mm
Figure 5-131. Charge Pressure Adjustment
pump speeds or higher charge flows the charge pressure
will rise over the rated setting.
3. Loosen the locknut and rotate the adjusting screw
clockwise to increase the setting; counterclockwise to
decrease it. Subtract the case pressure reading to com-
pute the actual charge pressure.
NOTE: Pressure change per turn is dependent on charge flow
entering pump.
4. While holding the adjusting screw, torque locknut to 12
Nm [9 lbft].
5. When you achieve the desired charge pressure setting,
remove the gauges and plug the ports.
DISPLACEMENT LIMITER ADJUSTMENT
1. Mark servo cylinder location in case it rotates during dis-
placement limiter adjustment.
2. Loosen the locknut (E550).
3. Rotate the adjusting screw (E450) based on the follow-
ing table. Rotating the adjusting screw clockwise
decreases the maximum displacement of the pump
while rotating the adjusting screw counterclockwise
increases the maximum displacement.
Charge pressure gauge port M3
0 - 50 bar [0 - 1000 psi]
1/4 in
24 N•m [17 lbf•ft]
Case drain port L2
0 - 10 bar [0 - 100 psi]
9/16 in
115 N•m [85 lbf•ft]
E450
4 mm
E550
13 mm
23 N•m
[17 lbf•ft]
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