The proportioning valve only lets a certain portion of the pressure through to the rear wheels so that the front wheels apply more braking force. If the proportioning valve were set to 70 percent and the brake pressure were 1,000 pounds per square inch (psi) for the front brakes, the rear brakes would get 700 psi. For more information on master cylinders and combination valves and related topics, check out the links on the next page.
And if you use a renewable energy source as the main source of hydrogen, a fuel cell can be considered a renewable energy source. Unlike conventional technologies, fuel is not burned but is combined in a chemical process. A fuel cell consists of two electrodes sandwiched around an electrolyte.
A fuel cell is an electrochemical cell that converts the chemical energy from a fuel into electricity through an electrochemical reaction of hydrogen fuel with oxygen or another oxidizing agent. Fuel cells are different from batteries in requiring a continuous source of fuel and oxygen to sustain the chemical reaction, whereas in a battery the chemical energy comes from chemicals already present in the battery. Fuel cells can produce electricity continuously for as long as fuel and oxygen are su