Starter Motor Working Method – Working Principle.

The starting motor working method is discussed in this article. Read the article and learn how a starter motor works?



Starter Motor Working Method


Starter Motor Working Method

Whereas in a generator the mechanical energy is converted into electrical energy. In a motor, the electrical energy is converted into mechanical energy. If a current from an outside source is applied to the terminal of a generator, the armature will revolve and the generator will act as a motor. 
The starter motor working method is based on the simple principle that when a current-carrying conductor is placed in a magnetic field, a mechanical force is experienced by the conductor, and the direction of the force is given by Fleming’s right-hand rule. 
Direction of current flow in alternator.


This Fig shows ac conductor carrying current in it. The direction of the current flow in it is indicated by the arrow. This causes the magnetic field around the conductor in an anticlockwise direction. This conductor is placed in the magnetic field of a magnet. 
The lines of force of this field are straight from the north pole to the south pole. The circular magnetic field to the right of the conductor is in the same direction as the straight-line magnetic field from the magnet. To the right of the conductor, it is in the opposite direction. This strengthens the magnetic field to the left and weakens the magnetic field to the right right of the conductor causing the magnetic lines of force to distort around the conductor. Because the magnetic lines of force have rubber-band characteristics, they try to straighten up to a minimum length. The more current flowing, the more lines of force will be distorted around the conductor and the stronger will be the push, the conductor will move faster. 

Working Principle of Simple Starter Motor

Working Principle of Simple Starter Motor


In an elementary motor, the conductor is U-shaped. Its two ends are connected to the two halves of a split copper ring. Stationary brushes have sliding contact with the ring, which is connected to a battery to supply the current to the conductor. The conductor is placed in a magnetic field. 
The U-shaped conductor loop and the split ring are designed so as to rotate together, and the brushes remain stationary. The split ring is called the commutator. The current flows from the battery through the brushes, commutator, and conductor in the direction shown by arrows. This causes the hand-left part of the conductor to be pushed upward and the right-hand part to be pushed downward. Thus, the conductor loop rotates in a clockwise direction. As the two sides of the loop reverse position, the direction of the current flows through the two sides also reverses. The force is thus continuous to rotate the loop- the motor is said to be running. 

Components of Starter Motor With Their Specific Work

A starter motor is a crucial component in an internal combustion engine’s starting system. This system is responsible for starting the engine with the help of cranking. Let’s break down the components of a starter motor and understand their working principles:

1. Armature

The armature rotates in the middle of the starter motor. It consists of a core made of soft iron with multiple windings of insulated wire. When electric current flows through these windings, it creates a magnetic field. This magnetic field interacts with the field coils.

2. Field Coils

The field coils are the types of coils of wire that surround the armature. These coils are connected to the battery and generate a strong magnetic field when current flows through them. This magnetic field then turns the magnetic armature field to rotate.

3. Commutator

The commutator is attached to one end of the armature shaft. It is a cylindrical shape material. It consists of multiple parts made of a conductive material separated by insulating material. As the armature starts the rotation, the commutator helps to reverse the direction of current flow in the armature windings. This ensures the continuous rotation in armature windings.

4. Brushes

Brushes are spring-loaded contacts that press against the commutator segments. Brushes are responsible for transferring the current from the battery to the armature windings. As the armature rotates, the brushes maintain contact with the commutator, ensuring a steady flow of current to the windings.

5. Solenoid

The solenoid is a type of electromagnetic switch, that connects the battery to the starter motor when the ignition key is turned to the “start” position. It consists of a coil of wire wrapped around a movable plunger. When current flows through the coil, it creates a magnetic field that pulls the plunger, engaging the starter motor’s pinion gear with the engine’s flywheel.
This system helps the engine to crank and start the engine. 


To get appreciable power in an actual motor, many conductor loops rotate in a strong magnetic field. The natural magnetic field of the magnetic poles is strengthened by field winding in such a direction as to aid the magnetic field between the two poles. 
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