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.
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