Nilfisk-Advance 56507009, Troubleshooting Manual

Page: 31 / 82

FORM NO. 56043129 - SR 1900 - 31
Symptom Possible Cause
Wheel drive functions sluggish or slow • Engine not operating in high-speed setting or engine speed is too
slow (2400 RPM).
• Air in hydraulic fluid (loose fittings).
• Propulsion pump inlet restriction (cavitation of hydraulic fluid).
• Worn drive wheel motor (*test working pressure & wheel drive
speed).
Wheel drive in one direction only • Inspect propulsion pump relief valves for:
A. Debris that allows valve seat to be held open,
B. Damaged or weak valve spring,
C. Valve unloading pressure setting too low for application.
No wheel drive in either direction • Check that pump bypass valve (tow valve) is in correct position.
• Check connection of foot pedal linkage (cable assembly) to
propulsion pump arm.
• Worn propulsion pump (*test output oil volume with a flow
meter).
• Defective propulsion pump charge circuit. Test its relief valve
pressure setting (65-100 psi).
• Worn or damaged wheel drive motor
No hydraulic system functions drive or accessory • Check for a damaged coupling connection from the engine to the
pump shaft input.
*Note: See in the hydraulic specification manual section, tables that list all the individual system component values (pressures, flows,
RPMs etc).
WHEEL DRIVE SYSTEM
Hydraulic Wheel Drive System
Troubleshooting Check List