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.

NOTE: Be sure to bleed the system after you connect the pressure gauges.





2. With the brakes applied, measure the input pressure and the output pressure. If the measured pressures are within the permissible ranges as illustrated, the proportioning valve is good.
3. Reconnect the brake lines in original position and bleed the system.





NOTE: This figure shows characteristics of the proportioning valve during pressure increase.