R2900G Load Haul Dump Braking System Service Brake System Pressure - Test Caterpillar

Show/hide table

Personal injury or death can result from escaping fluid under pressure. Escaping fluid under pressure, even a very small pin-hole size leak, can penetrate body tissue and cause serious injury and possible death. If fluid is injected into your skin, it must be treated by a doctor familiar with this type of injury. Always use a board or cardboard when checking for a leak.

With Service Brake Pressure Gauges

1. Move the machine to a hard, level surface.

2. Engage the parking brake and stop the engine.

3. Install the steering frame lock.

4. Start the engine and allow the hydraulic oil to reach normal operating temperature.
   Show/hide table

   Illustration 1	g01027322
   (1) Service brake pressure gauge for the front axle (2) Service brake pressure gauge for the rear axle

5. Observe service brake pressure gauge (1) and service brake pressure gauge (2). Both the pressure gauges should read 0 kPa (0 psi).

6. With the brake accumulator charging valve operating at cut-out pressure, depress and hold down the service brake pedal. Observe the service brake pressure gauges. The correct service brake pressure is 5860 ± 345 kPa (850 ± 50 psi).

7. If the service brake oil pressure is not correct and the brake accumulator charging valve is functioning correctly, replace the service brake control valve.

Without Service Brake Pressure Gauges

Note: Front service brake system pressure can be tested on the right side or the left side of the front axle. Rear service brake system pressure can be tested on the right side or the left side of the rear axle.

1. Move the machine to a hard, level surface.

2. Engage the parking brake and stop the engine.

3. Install the steering frame lock.

4. Release the braking system oil pressure.

   Reference: Refer to Systems Operation, Testing and Adjusting, "System Pressure - Release" for the machine that is being serviced.

   Show/hide table

   Illustration 2	g01028248
   Location of the test port for the service brakes (left side) (1) Plug

   Show/hide table

   Illustration 3	g01027854
   Location of the test port for the service brakes (right side) (1) Plug

5. Remove plug (1) from the test port for the service brake marked "S". Install a 6V-3965 Fitting As and a 3J-1907 O-Ring Seal into the test port marked "S".

6. Connect a 177-7861 Hose As and an 8T-0857 Pressure Gauge to the 6V-3965 Fitting As.

7. Purge the air from the braking system.

   Reference: Refer to Systems Operation, Testing and Adjusting, "Braking System Air - Purge" for the machine that is being serviced.

8. Start the engine and allow the hydraulic oil to reach normal operating temperature.

9. With the brake accumulator charging valve operating at cut-out pressure, depress and hold down the service brake pedal. Observe the 8T-0857 Pressure Gauge. The correct service brake pressure is 5860 ± 345 kPa (850 ± 50 psi).

10. If the service brake oil pressure is not correct and the brake accumulator charging valve is functioning correctly, replace the service brake control valve.

11. Release the braking system oil pressure.

    Reference: Refer to Systems Operation, Testing and Adjusting, "System Pressure - Release" for the machine that is being serviced.

12. Disconnect the 8T-0857 Pressure Gauge from the 6V-3965 Fitting As.

13. Remove the 6V-3965 Fitting As from the test port for the service brake. Install plug (1).

14. Purge the air from the braking system.

    Reference: Refer to Systems Operation, Testing and Adjusting, "Braking System Air - Purge" for the machine that is being serviced.