Railway Wagon Breaking System

About Railway Wagon Breaking System:- :- 

Braking system in railway wagon is very important to maintain speed as well as to decelerate speed and stop the train. It is done by converting kinetic energy into heat energy. The mostly used braking systems are air braking and vacuum braking system.

Air brakes are mostly used because of its advantages such as short braking distance, high braking force, compact light equipments etc. It uses compressed air as the force used to push the blocks on to the wheels. The vacuum brake is also very popular. They are similar to the air brakes only difference is that during application in vacuum brake, air is provided through brake pipe, while in air brake, air is removed from brake pipe. Electronically Controlled Pneumatic Braking system is used for overcome the problems associated with air braking system. In this case braking command is transmitted to wagons electronically by sending signals and codes. In Dynamic braking system and Regenerative braking system, motor works as a generator to convert mechanical energy into electrical energy & this electrical energy is converted into heat energy by main resistor or transmitted to overhead wire. To avoid accidents an Automatic Control Systems like Auxiliary Warning Systems are used to stop or automatically control speed of train according to signal aspects. 

Principle Parts

1.   Driver’s Brake Valve

2.   Exhasters

3.   Brake Pipe

4.   Dummy Coupling

5.   Coupled Hoses

6.   Brake Cylinder

7.   Vacuum Reservoir

8.   Ball Valve

Vacuum Reservoir

The operation of the Vacuum Brake relies on the difference in pressure between one side of the brake cylinder piston and the other.  In order to ensure there is always a source of vacuum available to operate the brake, a vacuum reservoir is provided on, or connected to the upper side of the piston.

Dummy Coupling

At the ends of each vehicle, a dummy coupling point is provided to allow the ends of the brake pipe hoses to be sealed when the vehicle is uncoupled.  The sealed dummy couplings prevent the vacuum being lost from the brake pipe.

Exhasters

A two-speed rotary machine fitted to a train to evacuate the atmospheric pressure from the brake pipe, reservoirs and brake cylinders to effect a brake release.  It is usually controlled from the driver's brake valve, being switched in at full speed to get a brake release or at slow speed to maintain the vacuum at its release level whilst the train is running.  Exhausters are normally driven off an electric motor but they can be run directly from a diesel engine. 

Brake Application 

The vacuum has been reduced by the admission of atmospheric pressure into the brake pipe. This has forced the piston upwards in the brake cylinder. By way of the connection to the brake rigging, the upward movement of the piston has caused the brake blocks to be applied to the wheels. The movement of the Piston in the brake cylinder relies on the fact that there is a pressure difference between the underside of the piston and the upper side. During the brake application, the vacuum in the brake pipe is reduced by admitting air from the atmosphere.  As the air enters the ball valve, it forces the ball upwards to close the connection to the vacuum reservoir. This ensures that the vacuum in the reservoir will not be reduced. At the same time, the air entering the underside of the brake cylinder creates an imbalance in the pressure compared with the pressure above the Piston.

Conclusion

Braking system is very important part of the railway wagon. Air braking system is very advantageous system. The biggest advantage that air brakes have over vacuum brakes is that the maximum pressure is 70psi instead of only 17psi. Air brake equipment can thus also be smaller and lighter. This advantage increases at high altitude, e.g. Peru. The main advantage for vacuum brakes is that the vacuum can be created by a steam ejector with no moving parts, whereas an air brake system requires a noisy compressor. Many vacuum braking systems are change to air braking system when the demand for braking power increases. The similarity in both is brake controlled by Brake pipe. Twin pipe system reduces the time required to charging the auxiliary reservoir. Both braking systems are also called automatic braking system, because if connecting hose is broken for any reason, pressure is lost from the brake pipe, because of this air pressure from auxiliary reservoir enters to the brake cylinder, and then brakes are apply because of movement of Piston.