JLG 740AJ, Service And Maintenance Manual

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SECTION 5 - BASIC HYDRAULIC INFOR M ATION AND SCHE M ATICS
5-80 3121160
INADEQUATE CHARGE PRESSURE WILL AFFECT THE OPERATOR'S ABILITY TO
CONTROL THE MACHINE.
Shut down the engine and connect the external control input
signal. Also reconnect the machine function(s), if discon-
nected earlier. Start the engine, checking to be certain the
pump remains in neutral. With the engine at normal operating
RPM, slowly check for forward and reverse machine operation.
Charge pressure may slightly decrease during forward or
reverse operation. Continue to cycle slowly between forward
and reverse for at least five minutes.
Shut down engine, remove gauges, and plug ports. Check res-
ervoir level and add filtered fluid if needed.
The machine is now ready for operation.
5.12 REXROTH VARIABLE DISPLACEMENT PUMP
(PRIOR TO SN 0300121643)
The variable displacement axial piston pump is a swashplate
design for hydrostatic drives in open circuits. The flow is pro-
portional 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 Dis-
placement 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 procedure is completed.