JLG 18RS Service Manual - Manual (Page 141)

SECTION 5 - HYDRAULICS
3121284 – JLG Lift – 5-51
5.4 HYDRAULIC DRIVE PUMP PRE-FILL PROCEDURE
The case of the hydraulic drive pump, MUST be pre-filled
before starting the engine. Failure to do so can cause prema-
ture failure of the pump.
1. Fill the hydraulic reservoir.
2. Determine if the hydraulic oil tank sight level gauge is
higher than other hydraulic components.
a. Determine if the hydraulic oil tank sight level gauge
is higher than the hydraulic drive pump assembly.
b. Determine if the hydraulic oil tank sight level gauge
is higher than all hydraulic hose loops or routings
between the hydraulic tank and the drive pump
assembly.
c. If sight level gauge is the highest hydraulic oil level
point, proceed to step 3.
d. If sight level gauge is NOT the highest hydraulic oil
level point, low pressure air may need to be applied
to the hydraulic oil tank (fill cap via air regulator) in
conjunction with step 4 to get hydraulic oil to move
over the air locks created by these high spots.
3. If the machine is to be equipped with a hydraulic oil
cooler option;
a. Determine if there is a hydraulic tee fitting installed
at the hydraulic drive pump that has a cap fitting
attached to it. (this will generally be at or near the
top of the hydraulic drive pump body). This cap fit-
ting is to be used to manually fill the hydraulic drive
pump case.
b. Remove cap fitting.
c. Fill hydraulic drive pump case with hydraulic oil.
d. Reattach and torque ‘cap’ fitting.
e. Pre-filling of the hydraulic drive pump w/oil cooler
option is complete (Step 4 can be omitted at this
point.)
4. If machine is NOT equipped with a hydraulic oil cooler
option;
a. Locate a case access port on the hydraulic drive
pump. Preferably one located at or near the top or
upper sides of the pump.
b. Using the proper wrench, remove the O-ring plug to
allow air to escape from the hydraulic drive pump
case.
c. Hydraulic oil will flow by gravity from the hydraulic
tank to the drive pump.
d. When hydraulic oil starts to flow out this port, the
pump is full.
e. Re-install the O-ring plug and torque.
5. Pre-filling of the hydraulic drive pump is complete.
5.5 PRESSURE SETTING PROCEDURE
NOTE: All pressures are set from the ground control station except
steer. The engine RPM's will be at 1800.
1. P1 MAIN RELIEF VALVE. Pressure gauge at the MP1
port. The P1 relief valve is located right next to the TS
port. Activate telescope in to the end of stroke and hold.
The gauge should read 2700 PSI. Using a ¾” wrench and
a ¼” allen wrench, turn clockwise to increase pressure,
counter-clockwise to decrease.
2. TELESCOPE OUT RELIEF VALVE. Pressure gauge at the
MP1 port. The Telescope out relief valve is located to the
left of the MP1 port. Activate telescope out to the end of
stroke and hold. The gauge should read 2200 PSI. Using
a ¾” wrench and a ¼” allen wrench, turn clockwise to
increase pressure, counterclockwise to decrease.
3. STEER RELIEF VALVE. Pressure gauge at the MP2 port.
Locate the P2 Main relief valve next to the MP2 port.
Loosen the jam nut and screw the adjustment clockwise,
until it bottoms out. This valve needs to be set higher
than the steer relief. Locate the Steer relief valve directly
below the P2 Main relief. (½ way down the manifold.)
From the platform, activate steer right. The gauge
should read 2750 psi. Using a ¾” wrench and a ¼” allen
wrench, turn clockwise to increase pressure, counter-
clockwise to decrease pressure. Checking steer left the
pressure will be 0-100 psi lower.