The triple safety valve is used to separate the line from the compressor into three autonomous circuits - two main ones (front axle wheel brake drive and rear bogie wheel brake drive) and one additional one (emergency brake release system drive), as well as for automatic shutdown of a damaged circuit with in order to maintain pressure in healthy circuits

The triple safety valve consists of a body 1, three covers 2, three valves 3, 6 and 8, three diaphragms 5 and two bypass valves 7.

Triple Safety Valve

Fig. 1. Three protective valve: 1 - body, 2 - cover, 3,6,8 - valves, 4 - spring, 5 - membrane, 7 - bypass valves

Compressed air from the compressor enters cavities A and B under valves 3 and 6 through the housing outlet.

When the pressure in the cavities reaches 520 kPa, valves 3 and 6 open, overcoming the forces of the balancing springs 4 and bending the membranes 5.

Compressed air through terminals I and II is directed to the receivers of the front axle and rear bogie brake drive circuits, respectively.

Simultaneously with the start of filling the receivers, valves 7 open and air enters the cavity above valve 8.

After reaching a pressure of 510 kPa, valve 8 opens and compressed air fills the circuit of the emergency brake release system.

If the circuits of the pneumatic actuator are in good condition, the membranes 5 additionally sag under the action of air pressure in cavities A, B and C. Therefore, valves 3, 6 and 8 are open even when the pressure in these cavities is below the specified value.

Kamaz Triple Safety Valve

If one of the circuits fails, for example, the I circuit, the pressure in the internal cavity of the faulty circuit (in the I output) decreases and valve 3 closes under the action of spring 4 .

But since in the cavity under valves 3, 6 and 8 proair must be supplied from the compressor, and the membranes of healthy circuits are affected compressed air from the receivers, valves 6 and 8 of healthy circuits open at a pressure lower than the opening pressure of the valve in the faulty circuit, and air will not enter the leaky circuit.

When the air pressure at the valve body inlet exceeds the set value, the non-hermetic circuit valve will open and the excess air will be vented to the atmosphere, i.e. the pressure in the hermetically sealed circuits will be maintained at a pressure corresponding to the opening pressure of the non-hermetic circuit valves (520 or 510 kPa).

In case of failure of the line coming from the compressor, valves 3, 6 and 8 close under the action of springs 4 and the pressure in the pneumatic drive circuits is maintained.

The receivers are used to accumulate compressed air and supply it to pneumatic brake actuators, as well as to supply other consumers and vehicle systems.

The cars are equipped with six receivers with a volume of 20 liters each, four of them are connected in pairs, forming a single volume of 40 liters. The receivers are mounted on the brackets of the car frame and attached to them with clamps.