Drive Pump Pre-Fill Procedure - JLG 400S Service And Maintenance Manual

5.5 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 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. Prefilling of the hydraulic drive pump w/oil cooler
option is complete (Step #4 can be omitted at this
point).s
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SECTION 5 - BASIC HYDRAULICS INFORMATION & SCHEMATICS
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.
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