Apart from being called the combination valve, it is also widely known as a proportioning valve. This valve is found in vehicle disc braking system. It has the duties of moderating pressure between the front and rear of the car brake. This has the duty or regulating the brake force applied to the different wheels as applying same braking force to all wheels of the car at the same time might result in the back wheels getting locked up. Vehicles that have drum brakes behind have much reduced for the brake drum compared to the disc brake available in the front.
This is where the duty of the proportioning valve comes into play. This regulates the amount of brake force supplied to each wheel of the car.
Over years of use the proportioning valve might wear out and fail in its work of regulating the flow of brake force to different wheels thus creating problems. Read below for the symptoms
Rear Wheels Gets Locked up
Since this valve has the primary work or reducing the flow of brake force to the wear wheels, a bad or worn or failing proportioning valve would show off by locking the rear brakes when the brake force is applied. This is very visible on wet surfaces. This is no good omen, so contact a mechanic to have this issue diagnosed and fixed immediately. It could require the replacement of the proportioning valve.
How to Test For Faults
After discovering there is an issue with the proportioning valve but yet u are not sure and want to test to confirm your suspicion yourself, there is a safe way of doing it. This is what you do, locate a parking lot without people and ensure you have someone with you. The duty of the second person is to stand and observe the rear tires. Have this person stay a safe distance from the car while you drive the car and attempt having a medium stop a few times and then a force stop. If in this test you have the rear brakes lock while the front still turns normally, then you having a bad or faulty proportional valve on your hands.
Who Should Repair/Replace A Bad Proportioning Valve?
Since the brake is a safety part of the car, it is advised that faulty brake parts be repaired by professionals in that field. This is imperative since `specialized tools are made for use by professionals to check and fix an otherwise hidden fault. It no gain saying that the brake is a vital safety part of the car that can be used in an emergency situation hence the need for it to work well.
As already stated above, look out to observe if you are having a rear brake that is locking particularly on wet surfaces and have the entire brake system inspected and replaced as soon as possible. Also ensure to have the job performed by a reputable mechanic to avoid safety issues during driving.
Go and have your car driven well.