Lever 1, rigidly secured to lever d, is linked by tie-rod 2 to the brake pedal. The force exerted on the pedal is transmitted through lever 1, plunger 3, sliding sleeve 4, spring 5 and its thrust member 6 to diaphragm 7 whose shaped nut 11 rests on plate 8. The edges of plate 8 rest on the stems of input valve 9, connected to the tank, and discharge valve 10, connected to the atmosphere. When the brake pedal is released, the input valve is closed and the open discharge valve connects the space under diaphragm 7 with the atmosphere. This space is connected through passage a to the brake chambers of the wheels (of an automobile). When the brake pedal is depressed, plate 8 opens input valve 9 and closes discharge valve 10. Compressed air from the tank is admitted through valve 9 and passage a into the brake chambers, producing the braking action. The pressure under diaphragm 7 increases, bending the diaphragm upward and compressing spring 5. Plate 8 follows the diaphragm. Since spring 12 of the input valve is taken several times stronger than spring 13 of the discharge valve, the input valve is closed and the discharge valve remains closed. If the brake pedal remains in a constant position, a certain constant pressure is maintained in the brake chambers. If the pivressure on the pedal is increased, a new amount of compressed air is delivered from the tank, the pressure in the brake chambers increases as does the braking action. If the pressure on the pedal is reduced, diaphragm 7 bends upward, the discharge valve is opened to some extent, and the pressure in the space under the diaphragm, as well as in the brake chambers, is reduced because a part of the air is released into the atmosphere. This reduces the braking action. When the pedal is released, spring 5 returns it to its initial position, diaphragm 7 is bent upward, input valve 9 remains closed, and discharge valve 10 is completely opened. This releases the brakes.
$4043$EHP,Va$