770G and 772G Off-Highway Truck (OEM) Hydraulic and Braking System: Brake Oil Overheating Troubleshooting

If an overheating condition in the brake system occurs, the operator will probably become aware of the overheating condition through the Caterpillar Monitoring System.

(1) Brake oil temperature gauge (2) Alert indicator(3) Action light

(4) Caterpillar Messenger screen

(5) Caterpillar Advisor screen

The machine receives a signal from the brake oil temperature sensor. The brake oil temperature sensor is located in the brake cooling return line before the hydraulic tank (torque converter, pulled unit, and brake section). Brake oil temperature gauge (1) will display this sensor input.

(A) Temperature reading of 124 °C (255 °F)(B) Temperature reading of 134 °C (273 °F)

Check brake oil temperature gauge (1) regularly. During this test sequence, do not allow the temperature of the brake oil to get too hot. Excessively hot oil may damage the brakes.

When the oil temperature is too hot for the current conditions, the action alarm, the alert indicator (2) and the action light (3) come on. Caterpillar Messenger or Truck Payload Management System (4) (if equipped) will display an event, or Caterpillar Advisor or Vital Information Management System (5) (if equipped) will display an event. If the brake oil is too hot, reduce the load on the machine or slow the machine speed. Also, downshift the transmission to a lower speed. For additional cooling, park the machine in a convenient location. Put the transmission in NEUTRAL, and run the engine at approximately 1500 rpm.

Problem: The oil temperature gauge indicates high temperature, but there are no alarm indicators.

The oil temperature is too hot according to brake oil temperature gauge (1). Action light (3) and the alert indicator (2) are off.

Probable Cause

Look at the events in message area (4) or (5). Determine the location of the error in the electrical system. Refer to Schematic, "770G/772G Off-Highway Truck Electrical Schematic". Consult your Caterpillar dealer for additional information.

Problem: The oil temperature is normal, but the action light is on.

The oil temperature is within the normal range, but action light (3) is on.

Note: Action light (3) is activated when the oil temperature reaches 124°C (255°F). The action light remains activated until the oil temperature decreases to approximately 113 °C (235 °F). Therefore, brake oil temperature gauge (1) may indicate a normal oil temperature while the action light is activated.

Probable Cause

Look at the events in message area (4) or (5). Determine the location of the error in the electrical system. Refer to Schematic, "770G/772G Off-Highway Truck Electrical Schematic". Consult your Caterpillar dealer for additional information.

Problem: The oil temperature is hot.

The oil temperature is too hot according to brake oil temperature gauge (1). Alert indicator (2) and the action light (3) are on. Message area (4) or (5) displays an event about brake oil temperature.

Probable Cause

The machine is being operated improperly.

ReferenceSee Operation and Maintenance Manual for the correct operating techniques of the brake and retarder system.

Operate the machine again. Make sure that engine rpm does not drop below 1700 rpm. Maintaining at least 1700 rpm ensures that enough oil flows through the brake oil coolers in order to keep the oil at normal operating temperature.

Problem: The oil temperature is hot on a properly operated machine.

The oil temperature is too hot according to brake oil temperature gauge (1). Alert indicator (2) and the action light (3) are still on after the machine is operated correctly. Message area (4) or (5) displays an event about the brake oil temperature.

Probable Cause

(6) Gear Pump (Brake, Brake Cooling)

View of Control Valve (Hoist)(7) Brake oil cooler relief valve

• There is a restriction in the oil cooling system. Refer to the brake system Testing and Adjusting, "Brake Cooling Pressure - Check" in order to determine if there is proper brake cooling oil flow.
• Gear Pump (Brake, Brake Cooling) (6) is excessively worn.
• The Brake oil cooler relief valve (7) is set too low. See the Hydraulic System Testing and Adjusting, "Relief Valve (Brake Oil Cooler) - Test and Adjust".

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770G and 772G Off-Highway Truck (OEM) Hydraulic and Braking System: Brake Oil Overheating Troubleshooting 2013-01-22T12:37:00-08:00 Rating: 4.5 Diposkan Oleh: Unknown