Hydraulics — Drive System Pressure Tests

Drive Pressure Test

This test determines the condition of the drive/piston pump.

STEP 1

Tilt the platform according to “Tilting the Platform” on page 61.

STEP 2

IMPORTANT: Start with a pressure gauge rated for a higher pressure than required, and move to lowerpressure gauges as needed. Gauges will be damaged if the pressure exceeds the capacity of the gauge.

On the drive/piston pump, connect pressure gauges rated for 414 bar (6000 psi) to test fittings (A) and (B).

STEP 3

Start the machine and allow it to warm to operating temperature (120° F / 49° C).

STEP 4

Carefully drive the mach ine against an immovable object, such as a tree.

STEP 5

Drive the machine against the object and record the pressure on gauge.

NOTE: Pressure will ramp up at either the (A) or (B) ports depending upon whether the drive is in forward or reverse.

STEP 6

Check the pressures at both low and high idle. Pressure should be 400 ± 15 bar (5800 ± 218 psi). in both forward and reverse.

NOTE: The higher value represents relief pressure for the drive system. Using the travel pedal, it should be possible at high idle to ramp pressure all the way up to relief pressure if the tires do not slip. Inability to reach relief pressure can indicate a malfunctioning relief valve, internal leakage in the system, or other drive circuit problems.

IMPORTANT: A malfunctioning relief valve or other internal problems could cause pressure to exceed relief pressure, If the pressure spikes higher than relief pressure, stop the pressure check and shut down the engine immediately. Exceeding relief pressure can cause serious damage to the hydraulic system.