The compressed air is used for obtaining brake application. The brake pipe and feed pipe run throughout the length of the coach. Brake pipe and feed pipe on consecutive coaches in the train are coupled to one another by means of respective hose couplings to form a continuous air passage from the locomotive to the rear end of the train. The compressed air is supplied to the brake pipe and feed pipe from the locomotive. The magnitude of braking force increases in steps with the corresponding reduction in brake pipe pressure and vice-versa.
Source: IRFCA
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Back again after some commitments with some braking action this time..
BRAKING SYSTEMS OF INDIAN RAILWAYS: I have mentioned in the first blog post of this that any railfan is concerned with the deceleration of a train as equally to that of acceleration as it is very very vital to have PROPER BRAKING SYSTEMS and personnel trained to PROPERLY and TIMELY USE BRAKING SYSTEMS. I would like to share two of IR's major braking systems as far as what i know:
AIR BRAKING SYSTEM: This is the most widely used braking system in...
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india in which there are single pipe and multipipe air brake operations usually for goods and passenger rakes respectively.Braking is achieved as compressed air forced the piston to move through the brake cylinder.
The twin pipe operation has brake and feed pipes passing from the locomotive to the last coach of the formation ensuring a continuity in brake pressure, compressed air is flown from the locomotive to al these compartments through these pipes. Each compartment has a Air reservoir and brake cylinder, the brake cylinder connected to brake pistons which actually move the brake shoes. The feed pipe continuously charges the auxilary reservoirs underneath every compartment irrespective of brake application. When the driver applies brakes, the compressed air in the brake pipe is actually released to the atmosphere, upon drop in equilibrium of brake and feed pressures, a valve releases compressed air from Auxiliary reservoir underneath every compartment to the brake cylinder thereby moving the brake piston connected to the shoe. This action is maintained as the AR is continuously charged by the FP irrespective of loss of BP till the driver releases the brake. When brake is released the brake pipe is closed again thereby building its pressure from LOCO compressor, when pressure in BP is in equilibrium with that of FP the compressed air in brake cylinder is discharged to atmosphere and braking is not in force anymore.
In a single pipe operation FP is not in use, braking is directly proportional to the air charge present in the AR under every wagon, braking is stopped once BP regains pressure, the AR is again continuously charged from BP once continuity is in place.
Railfanning Note: When chain is pulled, the BP valve under that particular compartment is released thereby releasing the continuity of the braking system forcing the brake cylinders to apply brakes. This is more or less like a failure of a bulb in a series electrical connection where others cannot glow anymore.Kindly note that till crew come and close the valve under the compartment, continuity is not regained.This however can be overcome in VACCUM BRAKING.