Wednesday, January 22, 2014

Electromagnetic Breaking system

Report and Presentation on Electromagnetic Breaking system

Electromagnetic brakes are likewise often used where an electric motor is already part of the machinery. For example, many hybrid gasoline/electric vehicles use the electric motor as a generator to charge electric batteries and also as a regenerative brake. Some diesel/electric railroad locomotives use the electric motors to generate electricity which is then sent to a resistor bank and dumped as heat. Some vehicles, such as some transit buses, do not already have an electric motor but use a secondary "retarder" brake that is effectively a generator with an internal short-circuit. Related types of such a brake are eddy current brakes, and electro-mechanical brakes (which actually are magnetically driven friction brakes, but nowadays are often just called “electromagnetic brakes” as well).




















Electromechanical brakes operate through an electric actuation, but transmit torque mechanically. When voltage or current is applied, the coil is energized thus creating a magnetic field. This then turns the coil to an electromagnet which develops magnetic lines of flux. This flux attracts the armature to the face of the brake. The armature and hub are normally mounted on the shaft that is rotating. Since the brake coil is mounted solidly, the brake armature, hub and shaft come to a halt in a short amount of time. When current or voltage is removed from the brake, the armature is free to turn with the shaft. In most designs, springs are the ones that hold the armature away from the brake surface when power is released, thus creating a small air gap. Cycling is achieved by turning on and off the voltage or current to the coil. Slippage should occur only during deceleration and when the brake is engaged, there should be no slippage once the brake comes to a full halt.  

 How It Works

Engagement: Electromechanical brakes operate via an electric actuation, but transmit torque mechanically. When voltage/current is applied, the coil is energized creating a magnetic field. This turns the coil into an electromagnet that develops magnetic lines of flux. The magnetic flux attracts the armature to the face of the brake. The armature and hub are normally mounted on the shaft (customer supplied) that is rotating. Since the brake coil is mounted solidly, the brake armature, hub and shaft come to a stop in a short amount of time.

Disengagement: When current/voltage is removed from the brake, the armature is free to turn with the shaft. In most designs, springs hold the armature away from the brake surface when power is released, creating a small air gap.

Cycling:Cycling: Cycling is achieved by turning the voltage/current to the coil on and off. Slippage should occur only during deceleration. When the brake is engaged, there should be no slippage once the brake comes to a full stop.

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