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Parts of a Dynamo Motor

by Steve Johnson

A dynamo motor, also known as an generator, is a device that can convert mechanical energy into an electric current. The concept of the dynamo is often attributed to Michael Faraday, who discovered that moving a magnet around a closed electric circuit can induce an electric current to flow in it. Modern dynamos or electric generators are made of several components that are essential for their function.

Magnetic Circuit

On a modern dynamo motor, the magnetic circuit is made of several parts that include an armature core, a yoke, an air gap, and poles. An armature core is composed of sheet steel with a blanking die and thin magnetic steel laminates. These laminated sheets are either welded or bonded together to keep them from splitting apart. The poles are either steel laminates or solid steel, and they have field coils that set up the magnetic fields in the machine. The top and bottom poles are also called a pole head and a pole shoe, respectively. These poles usually fan out and are designed to smooth the flow of air on the air gap. The yoke is the casing where the completed poles are mounted, and it provides the magnetic path between the poles.

Electric Circuit

The electric circuit is made of an armature winding, a commutator, a field winding and brushes. The armature winding is made up of copper wires that are insulated from the armature core. In a dynamo motor, the armature winding receives the voltage generated by the motor. Armature windings are connected to the commutator. The commutator acts as the mechanical rectifier that converts AC voltage to DC voltage, and it's usually made of silver-bearing copper. The commutator conducts the current to an external circuit through the brushes.

Mechanical Support

The mechanical support of a dynamo motor is composed of a shaft, a frame, end bells, and bearings. In most cases, the yoke and the frame are the same, and they are usually made of steel or aluminum that encases the whole dynamo motor. The armature is placed inside the frame by using a steel shaft supported by two lubricated bearings that can either be a ball, a roller, or a sleeve type. Once the armature is placed inside the frame, both ends of the frame are enclosed using the end bells. The end bells are usually made of the same material used on frames and yokes.

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