07-03-2011, 02:47 PM
Presented By :-
Sumit Khune
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Vacuum brake
Overview of Vacuum brake
History-
The vacuum brake is a braking system employed on trains and introduced in the mid-1860s. . A variant, the automatic vacuum brake system, became almost universal in British train equipment and in those countries influenced by British practice.
Overview of Vacuum brake
It was an alternative to the air brake, known as the vacuum brake. Like the air brake, the vacuum brake system is controlled through a brake pipe connecting a brake valve in the driver's cab with braking equipment on every vehicle.
Parts of the Vacuum Brake System
This diagram shows the principal parts of the vacuum brake system
Driver's Brake Valve- The means by which the driver controls the brake.
Exhauster- A two-speed rotary machine fitted to a train to evacuate the atmospheric pressure
Brake Pipe- The vacuum-carrying pipe running the length of the train
Dummy Coupling- At the ends of each vehicle
Coupled Hoses- The brake pipe is carried between adjacent vehicles through flexible hoses
Brake Cylinder - The movement of the piston contained inside the cylinder operates the brakes through links called "rigging“
Vacuum Reservoir -difference in pressure between one side of the brake cylinder piston and the other.
Brake Block - made of cast iron or some composition material
Brake Rigging - the movement of the brake cylinder piston transmits pressure to the brake blocks on each wheel
Ball Valve -needed to ensure that the vacuum in the vacuum reservoir is maintained at the required level
How the automatic vacuum brake works
Vacuum brake cylinder in running position: the vacuum is the same above and below the piston
How the automatic vacuum brake works
Air at atmospheric pressure from the train pipe is admitted below the piston, which is forced up
Present-day use of vacuum brakes
Today's largest operators of trains equipped with vacuum brakes are the Railways of India and Spoornet (South Africa), however there are also trains with air brakes and dual brakes in use.