INDIAN RAILWAYS – GRADUATED & QUICK SERVICE APPLICATION

GRADUATED APPLICATION

When a reduction in BP pressure is caused by the Driver’s Brake Valve. The air pressure under the diaphragm in chamber 5 drops quickly causing the diaphragm to flex down and close the passage to the CR, thus isolating it from BP in chamber 1 and 2 due to the isolating of CT a pressure difference  is set across the diaphragm separating these two chambers which lift the Hollow stem to open the inlet valve. Then air from MR will flow into chamber 9 from where it is led into chambers 11 and 16 and also to the bottom side of inlet valve in chamber 11 the air pressure builds up under diaphragm and lifts it up, thereby withdrawing the pin from valve 6. In inlet valve, air passes through the valve opening and also enters chamber 10 and lifts the diaphragm of inlet valve and closes the valve passage. A pressure of 0.5+0.2 bar is enough to close the inlet valve passage. Once this passage is closed air flows only through the “application choke – goods” into the BC. In chamber 8 on top of the upper diaphragm assembly downwards and finally Bringing the inlet Exhaust valve to lap position. As soon as the balance is reached in this diaphragm assembly, no more  air can flow into BC. In case of full service application or an emergency application, the maximum BC present that is requires to balance the main valve diaphragm assembly is 3.8+0.1 bar with BP regime pressure set at 5 bar. Similarly every time the BP pressure is reduced in steps, the phenomenon will repeat, and air from AR will gradually flow into BC in corresponding steps.

QUICK SERVICE APPLICATION

As soon as the BP pressure is reduced  , the pressure in chamber 4 under the QSB upper diaphragm is reduced, causing the diaphragm assembly of the build to move down to open inlet valve 13. Then air enters build 12 and builds up pressure under the seat in chamber 17, developing an upwards force on the diaphragm assembly. This sudden surge of a large volume of air causes a local pressure depression equal to 0.4 bar in chamber 2 of the  main valve, thus helping the quick propagation of the BP pressure reduction through the length of train. The builds is exhausted once the BC pressure reaches around 0.8bar during the brake release operation. This facilities quick service propagation. Should an application be made immediately.