A Combination Valve, commonly called a Proportioning Valve, is just what the name implies…a valve that does a combination of things. The valves are available for both disc/drum and for disc/disc brake systems. Valves for both configurations contain a Proportioning Valve and a Brake Pressure Differential Switch while the disc/drum valves also contain a Metering Valve. What is all of this stuff and what does it do? Read on and we’ll explain…..