770G and 772G Off-Highway Truck (OEM) Hydraulic and Braking System: Operational Checks

WARNING: Personal injury or death can result from sudden machine movement.Sudden movement of the machine or the release of oil under pressure can cause injury to persons on or near the machine. To prevent possible injury before testing and adjusting the hydraulic system, perform the procedure in the Testing and Adjusting, "General Information" section.

NOTICE
Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting, and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Refer to Special Publication, NENG2500, "Dealer Service Tool Catalog" for tools and supplies suitable to collect and contain fluids on Cat products.Dispose of all fluids according to local regulations and mandates.

Service Brake Check

Note: The Brake Valve (Front Service Brake) activates the front service brakes. The Brake Valve (Rear Service Brake, Retarder Control, Traction Control) activates the rear brakes.

1. Upon starting of the engine, allow the brake accumulators to charge and allow the accumulator charging valve to reach the cut out pressure.

2. Move the transmission control to the NEUTRAL position. When the transmission control is moved from the PARK position, the parking brakes are automatically disengaged.

3. Depress the service brake control fully.

4. Move the transmission control to the FIRST GEAR position.

5. Increase engine speed to 1200 rpm. The machine should not move.

6. If the machine moves, inspect the brake system for wear or for damage. See Systems Operation/Testing and Adjusting, "Braking System Troubleshooting".

Parking Brake Check

Note: The Brake Valve (Parking) activates the rear wheel brakes. The wheel brakes are applied by spring pressure and the wheel brakes are released by oil pressure. The parking brake is applied when the transmission control is in the PARK position. The parking brakes are applied proportionally by the secondary brake pedal.
The parking brake tests consist of the following two tests.

Brake Drive Through Test

Note: This test should be conducted when the truck is empty.

1. Move the parking brake to the ON position.

2. Move the transmission control to the FIRST GEAR position.

3. Increase engine speed to 1200 rpm. The machine should not move.

4. If the machine moves, inspect the parking brake system for wear or for damage. See the Systems Operation/Testing And Adjusting, "Braking System Troubleshooting".

Brake Slope Test

Note: This test should be conducted when the truck is loaded to the normal rated capacity.

1. Load the truck to the normal rated capacity.

2. Park the machine on a slope of no more than 15 percent.

3. Depress the service brake pedal.

4. Shift the transmission control to PARK. Shifting the transmission to PARK will apply the parking brakes.

5. Release the service brake pedal.

6. If the machine moves, inspect the parking brake system for wear or for damage. See the Systems Operation/Testing And Adjusting, "Braking System Troubleshooting".

Retarder Brake Check

Note: The Brake Valve (Front Service Brake) activates the front service brakes. The Brake Valve (Rear Service Brake, Retarder Control, Traction Control) activates the rear brakes.

1. Stop the machine on a level area.

2. Pull the manual retarder control lever completely to the DOWN position.

3. Move the transmission control to the FIRST GEAR position.

4. Increase the engine speed to 1050 rpm. The machine should not move.

5. If the machine moves, inspect the brake system for wear or for damage. See Systems Operation/Testing and Adjusting, "Braking System Troubleshooting".

Brake Cooling System Check

Refer to Systems Operation/Testing and Adjusting, "Brake Oil Overheating Troubleshooting" for a brake cooling system that is overheated.

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770G and 772G Off-Highway Truck (OEM) Hydraulic and Braking System: Operational Checks 2013-01-22T12:29:00-08:00 Rating: 4.5 Diposkan Oleh: Unknown