Types of electrical braking pdf


















The atmospheric valve remains open and the vacuum valve remains closed when the brakes are not applied. When the brake pedal is depressed, the atmospheric valve opens, the vacuum valve also piston opens and the engine exhausts air inside the servo cylinder. Working against flexible diaphragms in the brake chamber, air brakes are applied by compressed air pressure rather than foot pressure.

The diaphragms are connected to the brake rod which connects to the brake operating cams on the wheel brakes. These diaphragms are controlled through valves operated by hand or foot. The brake valve controls brake operation by directing the flow of air from a reservoir against diaphragms in the brake chambers when the brakes are applied, and from brake chambers to the atmosphere when the brakes are released.

The hydraulic brakes are applied by fluid pressure. The pedal force is transmitting to the brake shoe by means of a confined liquid through force transmission. The force applying to the pedal is multiplied and transmitted to all the brake shoes by a force transmission system. The master cylinder is connected by tubing to the wheel cylinder on each of the four wheels. The system is filling with the liquid under light pressure when the brakes are not in operation.

The liquid is known as brake fluid is a mixture of glycerine and alcohol or castor oil, denatured alcohol, and some additives. Electric brakes are also using for some motor vehicles, although these are not very popular. Warner electric brake is one of the examples of such brakes.

These types of braking system have an electromagnet within the brake drum. The brake is worked when the current from the battery is used to energize the electromagnet, Which activates the mechanism to extend the brake shoe against the brake drum, and thus brake applied. The severity of braking is controlled through a rheostat, which is driven by the driver through the foot-pedal.

It is necessary to take only the current from the battery to the electromagnet. In addition, these are much faster than other types of brakes. The below figure shows the self-energizing brake diagram.

Drum-type hydraulic wheel brakes are provided with self-activated or servo features, In which the force of the rotating drum is used to increase the brake pressure. When the vehicle is traveling forward, the drum starts rotating in an anticlockwise direction. Because the primary shoe is attached to the secondary shoe at the bottom position, the secondary shoe is forced against the anchor pin that is located at the top.

This action causes both shoes to be in severe contact with the drum and the braking pressure is applied more evenly. A great braking force is to be needed to apply the brakes in case of motor vehicles fitted with disc brakes, as well as for heavy commercial vehicles.

Power assisted brakes are using to equate the limited strength of the driver with the great braking force. Generally, the entire intake manifold vacuum is used by the power-assisted system. Therefore, they are also known as vacuum brakes. In this system, when the brake pedal is depressed, fluid is forced from the master cylinder to the primary chamber of the wheel cylinder. Now the intermediate piston provided at the end of the master cylinder also closes the diaphragm valve in the reaction chamber.

This results in isolating the vacuum from the air side of the boost system. The sir control spool is opened to admit air at atmospheric pressure with the movement of the intermediate piston further along its bore. If you have liked this article then please share it with your friends.

Enter your email address. Sign Up. He is a mechanical engineer by profession and has five years of experience in the mechanical engineering field. The direction of the motor gets reversed and inturn causes braking the wheel. In generators, the use of the plugging type braking system results in decreased speed due to the reversal of terminals of the supply, reversal of torque, and restriction of rotation of the motor.

An external resistor is used to limit the current flowing through the plugging circuit. The more power is wasted during the plugging. It is also known as dynamic resistor braking or dynamic rheostat braking. In this type, the resistance is provided to the motor by the rheostat connected to the circuit is capable of acceleration or deceleration of the vehicle.

This resistance helps to reduce the speed and stops the electric vehicle. The resistor or rheostat in the circuit dissipates excess energy on the capacitor by connecting a resistor in parallel with the capacitor.

When the motor acts as a generator, reverse current flows through the circuit, and the torque changes and causes braking. The resistance in the circuit can be removed to maintain the constant torque while braking the motor. The hydraulic braking system uses liquid as a pressure for the movement or force or to increase the force. The pressure applied on a liquid can be called as hydraulic pressure.

This hydraulic pressure helps in braking the vehicle by transferring pressure to the final brake drum or disc rotor via braking lines. Instead of using brake fluids, hydraulic brakes are used to accelerate or stopping the vehicle. It is mostly used in all types of bikes and cars because of their effectiveness, the highest brake generating force capacity. Blaise Pascal states that when the pressure applied to a fluid confined incompressible fluid in a system can transmit equal pressure in all directions throughout the fluid.

This law was given by Blaise Pascal in A braking system is a mechanical device that helps in accelerating or decelerating the speed of the system. It inhibits motion by absorbing energy from the system. The braking system is necessary in control systems to ensure the speed and time profile, stops the running systems in case of emergency, ensures system stability when not in use.

The two types of brake assist systems are hydraulic brake assist system and mechanical braking assist system. Thus, this is all about the braking — definition, types, mechanical braking, electrical braking, regenerative braking, plugging type braking, dynamic braking, and hydraulic braking systems.

The torque-slip characteristics for motoring and braking operation of 3 phase induction motor is shown here, Uses: We use dynamic or rheostat braking in cranes. Plugging On Induction Motor Plugging induction motor braking is applied by just reversing the supply phase sequence. Due to the reversal of phase sequence, the direction of rotating magnetic field gets reversed. This produces a torque in the reverse direction and the motor tries to rotate in opposite direction.

This opposite flux acts as brake and it slows down the motor. During plugging the slip is 2 - s , if the original slip of the running motor is s.

Disadvantages of plugging induction motor braking : 1. This heat is more than produced when rotor is normally locked. So we can't apply plugging frequently as due to high heat produced rotor which can damage or melt the rotor bars and even may over heat the stator as well. Advantages of plugging induction motor braking : 1. It the quickest way. Braking On Induction Motor This is also similar to dynamic braking of induction motor, connections of stator are disconnected from the supply and connected to a dc source.

When d. As rotor is rotating, rotor cuts the flux produced by the stationary poles. Thus the a. This voltage produces an a. The motor works as a generator and the R losses are dissipated at the expenditure of kinetic energy stored in the rotating parts.

Thus D. C dynamic braking is achieved. This is the quick way to stop induction motor along with high load. Advantages of d. Quick, Less heat produced as compared to the plugging method.



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