773E and 775E Off-Highway Truck Hydraulic System: Hoist System Troubleshooting

Hoist and brake gear pump (1) Hoist pump section(2) Brake pump section

Performance tests can be used for diagnosing poor performance and for finding the source of oil leakage inside the hydraulic system.

Problem: The hoist system does not operate.

Probable Cause

• The parameter setting for the hoist system has not been enabled.

Problem: The hoist and brake gear pump makes noise and the cylinder rods do not move evenly. Also, there are air bubbles in the oil.

Probable Cause

• The low pressure relief valve in the hoist control valve opens at low oil pressure.
• The high pressure relief valve in the hoist control valve opens at low oil pressure.
• There is a loose connection in the oil line of the inlet side of hoist pump section (1) .
• There is a loose connection in the oil line of the inlet side of brake pump section (2) .
• The hoist pump section (1) is too worn.

Problem: The temperature of the oil is too hot.

Probable Causes

• The viscosity of the oil is incorrect.
• The low pressure relief valve in the hoist control valve opens at low oil pressure.
• The high pressure relief valve in the hoist control valve opens at low oil pressure.
• The hoist pump section (1) is too worn.
• The brake pump section (2) is too worn.
• There is a restriction in an oil passage.
• The load on the system is too high.

Problem: The output of the hoist pump section is too low.

Probable Cause

• The hoist and brake hydraulic tank oil level is too low.
• The viscosity of the oil is incorrect.
• The hoist pump section (1) is too worn.

Problem: The pressure of the oil is too low.

Probable Cause

• The low pressure relief valve in the hoist control valve opens at low oil pressure.
• The high pressure relief valve in the hoist control valve opens at low oil pressure.
• The hoist pump section (1) is too worn.
• An O-ring seal failed in the hydraulic system.

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773E and 775E Off-Highway Truck Hydraulic System: Hoist System Troubleshooting 2013-01-10T19:02:00-08:00 Rating: 4.5 Diposkan Oleh: Unknown