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 (split point).
Standard value: 1.72 - 2.7 MPa (249 - 391 psi)
2. Output fluid pressure when input fluid pressure is 7.0 MPa (101.5 psi).
Standard value: 2.9 - 3.5 MPa (420 - 507 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.