Brake Proportioning/Combination Valve: Testing and Inspection

Check Proportioning Valve Function With Pressure Gauge:

Output Pressure Measurements:

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. Service and Repair
3. While gradually depressing the brake pedal, make the following measurements and check that the measured values are within the allowable range.
a. Output pressure begins to drop relative to input pressure (split point). The standard value is 3.25-3.75 MPa (462-533 psi)
b. Output fluid pressure when input fluid pressure is 7.0 MPa (996 psi). The standard value is 4.25 MPa (604 psi)
c. Output pressure difference between left and right brake lines. The limit is 0.4 MPa (57 psi)
4. If the measured pressures are not within allowable ranges, replace the proportioning valve.