A Kaiser valve or “king” vale is a pneumatic valve on the tractor that proportions or allocates braking air pressure to different axles of the tractor trailer when the brake pedal is depressed. Because most tractor trailers have 5 axles, each with brakes, the air used to initiate the brakes must be allocated in a precise order from the back to the front axles so the combo vehicle doesn’t jack-knife. The Kaiser valve has been incorporated in the overall anti-lock braking system of modern trucks. Although a fully loaded truck can weigh 10- 20 times as much as an automobile (40,000 to 80,000 lbs.), trucks can break just slightly slower than a car.