Return to Master Table of Contents PROCEDURAL TROUBLESHOOTING BASELINE RECOMMENDATIONS INITIAL CHECKS AND TESTS TO ESTABLISH OPERATING CONDITION OF THE EXCAVATOR Triage Summary An excavator that fails to deliver designed performance should be checked for the following: Hydraulic flow, first, and Hydraulic pressure, afterwards, in a specified order of priority through different points of the system. To verify adequate available hydraulic flow, before any other tests are performed through the circuit:
Check engine operation - at 2,150 RPM with no load at 2,000 RPM stall load If engine RPM drops excessively with a load or fails to surpass rated speed (1,900 RPM), performance problems may be due to inadequate hydraulic flow caused by lagging rotational speed. NOTE: Verify actual flow on the excavator against rated performance, with a flow meter. If engine tests meet specifications and adequate torque and horsepower are available at the pump drive flex coupling, pull out the electrical tray under the operator’s seat to inspect the self-diagnostic display. If the EPOS trouble code display is clear, check hydraulic functions in the following sequence:
Pilot pressure Negacon, negative control pressure Main relief pressure (front and rear pump) Swing pressure Port relief pressure (individual control functions; crowd, bucket, boom, travel) Power boost circuit Standard performance tests; cylinder speed, hydraulic motor (travel and swing) speed, cylinder oil-tightness "permissible drift" test NOTE: System specification performance tests of individual activator function are determined by flow rate through the component or circuit, not the control pressure or system pressure available to the actuator.
Poor flow through the individual circuit may indicate that the component is worn beyond tolerance limits, while all other hydraulic functions are adequate. IMPORTANT It is suggested that the troubleshooter maintain the testing sequence of the preceding list. Checks and adjustments nearer the middle or the end of the list may depend on adequate functioning of systems tested nearer the top of the list. Page 11 Hydraulic System Troubleshooting, Testing and Adjustment