Cylinder Checking Procedure; Cylinders Without Counterbalance Valves And Steer Cylinder; Lift Pressure Setting Procedure - Oshkosh JLG 1930ES Service Maintenance Manual

SECTION 4 - HYDRAULICS
4.4

CYLINDER CHECKING PROCEDURE

NOTE: Cylinder check must be performed anytime a system
component is replaced or when improper system
operation is suspected.
Cylinders Without Counterbalance Valves and
Steer Cylinder
1. Using all applicable safety precautions, activate
pump motor and fully extend cylinder to be
checked.
2. Carefully disconnect hydraulic hoses from retract
port of cylinder. There will be some initial weeping
of hydraulic fluid which can be caught in a suitable
container. After the initial discharge, there should
be no further drainage from the retract port.
3. Activate pump motor and extend cylinder.
4. If cylinder retract port leakage is less than 6-8
drops per minute, carefully reconnect hose to port
and retract cylinder. If leakage continues at a rate
of 6-8 drops per minute or more, cylinder repair
must be made.
5. With cylinder fully retracted, shut down machine
power and carefully disconnect hydraulic hose
from cylinder extend port.
6. Activate pump motor and retract cylinder. Check
extend port for leakage.
7. If extend port leakage is less than 6-8 drops per
minute, carefully reconnect hose to extend port,
than activate cylinder through one complete cycle
and check for leaks. If leakage continues at a rate
of 6-8 drops per minute or more, cylinder repairs
must be made.
4-4
4.5

LIFT PRESSURE SETTING PROCEDURE

1. Large Nut
2. Pressure Setting Screw
3. P port
Figure 4-1. Lift Pressure Setting
1. Place 120% of the rated load of the machine on
the platform.
2. Increase lift pressure to raise the platform and set
the safety prop.
3. Locate the Large Nut (1) on the underside of the
valve block.
4. Using a 7/8 in. wrench, remove the large nut (1).
This will expose the Pressure Setting Screw (2).
5. Remove plug from P port (3) and install a pressure
gauge.
6. Raise the platform and take a pressure reading.
7. Adjust the Pressure Setting Screw to reach the
proper lift pressure per model as listed in Table 4-
1.
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