Load Compensator: Testing and Inspection

Rear Brakes Locking On Application

Height Sensing Proportioning Valve:

Fig. 3 Master cylinder & brake warning switch.:

Symptom When a premature rear wheel slide is obtained on brake application, it could be an indication that the fluid pressure to the rear brakes is above the reduction ratio for the rear line pressure and that a malfunction has occurred within the proportioning valve unit which should be tested.

To test the proportioning valve, proceed as follows:
1. Disconnect the external spring at the valve end.
2. Install one gauge and "T" of set C4007-A or equivalent in the line from either master cylinder port to the brake valve assembly.
3. Install the second gauge to either rear brake outlet port between proportioning valve assembly and the rear brake line.
4. Bleed both hydraulic circuits and the gauges.
5. Have a helper exert pressure on the brake pedal (holding pressure) to get a reading on the valve inlet gauge and check the reading on the outlet gauge.
- The inlet pressure should be 500 psi and the outlet pressure should be 100-200 psi.
- If not, replace the valve torque mounting bolts to 250 inch lbs.
- If the valve tests OK re-adjust external spring and road test vehicle.