What is the main purpose and function of the brake combination valve?

It senses pressure going to the front brakes only. When you press the pedal and pressure rises, the switch is forced closed. This completes the electrical circuit and turns on the Brake Lights. This type of combination valve eliminates the need for a brake light switch on the pedal assembly.

What are the 3 functions of a 3 function combination valve?

A three-function combination valve contains the proportioning valve, metering valve, and a pressure differential switch.

How do brake proportioning valves work?

The proportioning valve reduces the pressure to the rear brakes. If equal braking force were applied to all four wheels during a stop, the rear wheels would lock-up before the front wheels. The proportioning valve only lets a portion of the amount of pressure to the rear wheels thus preventing rear wheel lock-up.

What is the purpose of metering valve?

A brake metering valve is used to Balance the Braking Forces. It is only found on vehicles with front disc and rear drum brakes. The metering valve holds back fluid to the front brakes until enough pressure is created to overcome the return springs inside the rear drums. It is also known as a “metering block.”

What do combination valves contain?

Combination valves include a metering valve, a proportioning valve, and a pressure differential switch. This valve operates every time you use your brakes and gets a lot of work, which means it may wear out at some point in the life of your vehicle.

What are the purposes of the proportioning metering and pressure differential valves in a brake system?

The proportioning valves are found on vehicles with front disc, rear drum brake systems. They keep the rear brakes from locking up during sudden, hard braking by restricting fluid pressure to the rear brakes.

Can a proportioning valve cause front brakes to lock up?

The proportioning valve is able to reduce pressure to the rear brakes to prevent rear wheel lock up when the brakes are heavily applied. The metering valve is used on disc/drum combination brake systems to control front brake lock up during initial braking.

Can you eliminate a proportioning valve?

the only downside to getting rid of the stock prop valve is that the brake light won’t light up when you lose pressure in either the front or rear brakes. another option is to gut the proportioning part of the prop valve so that it functions as a distribution block and run an adjustable valve in the rear line.

What are the purposes of the proportioning metering and pressure differential valves?

The metering valve works with a proportioning valve to achieve balanced braking in these systems. A proportioning valve is located in-line to the rear brake system. It’s used to prevent rear-wheel lockup during sudden and hard braking situations.

What is the purpose of the pressure differential valve?

The differential valves are used to detect differential pressure. Detection of malfunction or failure of one of the two or more hydraulic circuits is the most common use.