CONTROL GP-SERVICE BRAKE 3E6208 - Caterpillar

Note: There are two separate procedures that may be used to check the operation of the accumulator charging valve and several associated components.ReferenceProcedure 1 is a quick method for checking the cut-out pressure. This procedure also indicates whether the brake accumulator oil pressure sensor and the alert indicator are working correctly. The procedure provides an estimate of the accumulator precharge pressure and an estimate of the number of brake applications before the brake accumulator oil pressure alert indicator turns on.ReferenceProcedure 2 determines whether the cut-in pressure and the cut-out pressure are correct. This procedure also provides the steps for adjusting the brake accumulator charging valve.Procedure 1
Stop the engine. Engage the parking brake. Depress the service brake pedal at least 70 times to remove the oil pressure from the brake accumulators.
Illustration 1 g03385294
Location of the brake accumulator pressure taps (1) Brake accumulator oil pressure sensor (2) Accumulator charging valve (3) Rear brake accumulator pressure tap (4) Front brake accumulator pressure tap
Connect a hose assembly with an 8T-0859 Pressure Gauge (0 to 25,000 kPa (0 to 3,600 psi)) to pressure tap (3) or pressure tap (4) on accumulator charging valve (2) .
Observe the pressure gauge. Before the engine is started, the oil pressure must be 0 kPa (0 psi).
Start the engine. Allow the oil pressure to increase to the cut-out pressure. The correct cut-out pressure should be 14480 345 kPa (2100 50 psi).
After the brake accumulators have been charged and the cut-out pressure has been obtained, stop the engine.
Turn the engine start switch key to the ON position, but do not start the engine.
Apply the service brakes repeatedly, pausing for a second or two between each brake application. Count the number of brake applications. Observe the pressure gauge as you apply the brakes.
Illustration 2 g03689980
Caterpillar Monitoring System display (5) Brake accumulator oil pressure alert indicator
When, the reading on the pressure gauge decreases to 8275 345 kPa (1200 50 psi), brake accumulator oil pressure alert indicator (5) on the dash panel should illuminate, indicating operational status of brake accumulator oil pressure alert indicator (5) and operational status of brake accumulator oil pressure sensor (1) .
Continue to apply the service brakes. Pause for one or two second between each brake application. Also, continue counting the number of brake applications while observing the pressure gauge. The approximate nitrogen precharge pressure in the brake accumulators will be indicated, when the pressure drops off rapidly.
Determine the number of brake applications that were required before the sudden pressure drop off in Step 9. The number of service brake applications should be approximately 65 times.
If the accumulator charging valve cut-out pressure is not within the specification, complete Steps 7 through 2 in "Procedure 2". If the nitrogen precharge pressure is not within the specification, test the brake accumulators for the correct charge pressure.ReferenceFor the correct nitrogen precharge pressure and for information on testing the brake accumulators, refer to Brake Accumulator - Test and Charge, "Braking System, System Operation, Testing and Adjusting", for the machine