Brake Proportioning/Combination Valve: Testing and Inspection

PROPORTIONING VALVE FUNCTION TEST





1. Connect two pressure gauges, one each to the input side and output side of the proportioning valve, as shown.
2. Air bleed the brake line and the pressure gauge.
3. While gradually depressing the brake pedal, make the following measurements and check to be sure that the measured values are within the allowable range.





1) Output pressure begins to drop relative to input pressure.

Standard value: 3.25 - 3.75 MPa (462 - 533 psi)

2) Output fluid pressure when input fluid pressure is 7.0 MPa (996 psi).

Standard value: 4.25 MPa (604 psi)

3) Output pressure difference between left and right brake lines

Limit: 0.4 MPa (57 psi)

4. If the measured pressures are not within allowable ranges, replace the proportioning valve.