JLG 740A, Service And Maintenance Manual

Page: 306 / 408

SECTION 5 - HYDRAULICS
5-20 – JLG Lift – 3121160
5.10 HYDRAULIC COMPONENT START-UP
PROCEDURES AND
RECOMMENDATIONS
From a hydrostatic component standpoint, the goal at
system start up is to put into functional operation, the
hydrostatic system in such a way as to preserve the
designed life span of the system. The following start-up
procedure should be adhered to whenever a new pump
or motor is initially installed into a machine, or a system is
restarted after either a pump or motor has been removed
and/or replaced.
THE FOLLOWING PROCEDURE MAY REQUIRE THE MACHINE TO
BE DISABLED (WHEELS RAISED OFF THE GROUND, WORK FUNC-
TIONS DISCONNECTED, ETC.) WHILE PERFORMING THE PROCE-
DURE IN ORDER TO PREVENT INJURY. TAKE NECESSARY SAFETY
PRECAUTIONS BEFORE MOVING THE VEHICLE/MACHINE.
Prior to installing the pump and/or motor, inspect the
unit(s) for damage that may have been incurred during
shipping and handling. Make certain that all system com-
ponents (reservoir, hoses, valves, fittings, heat exchanger,
etc.) are clean prior to filling with fluid.
Fill the reservoir with recommended hydraulic fluid. This
fluid should be passed through a 10 micron (nominal, no
bypass) filter prior to entering the reservoir. The use of
contaminated fluid will cause damage to the components,
which may result in unexpected vehicle/machine move-
ment.
NOTE: If a pump or motor is being replaced due to internal
damage, the remaining units (pump or motors) need
to be inspected for damage and contamination, and
the entire hydraulic system will need to be flushed
and the fluid replaced. Failure to do so may cause
considerable damage to the entire system.
5.11 REXROTH VARIABLE DISPLACEMENT
PUMP (PRIOR TO S/N 0300121643)
The variable displacement axial piston pump is a swash-
plate design for hydrostatic drives in open circuits. The
flow is proportional to the speed and the displacement. By
adjusting the swashplate, it is possible to vary the flow
steplessly. See Figure 2-43 for pressure settings and
schematic.
1. Variable, swashplate design SAE nominal pressure
3600 psi (248 bar), peak pressure 4600 psi (317
bar).
2. Pump, open circuit.
3. Displacement Vgmax 2.75 in
3
(45 cm
3
).
4. Pressure and flow control. (DFR1)
5. Series 52.
6. Clockwise rotation.
7. NBR seals (Nitrile rubber to DIN ISO 1629)
8. SAE 1.00 in. (2.54 cm) splined shaft.(not suitable for
through drive)
9. SAE 2 bolt mounting Flange - SAE 101-2 (B)
NOTE: The Drive Pump and Displacement Pump must be
filled with oil before starting the engine. As the tank
is being filled, remove the specified plug from the
Variable Displacement Pump. As oil enters the tank
it flows to the pumps, fills them and flows out the port
where the plug was removed. Removing the plug
gives the air a place to escape. In approx. 5 min.,oil
should flow out the port. Replace the plug, the proce-
dure is completed.