ELBOW 8K0968 - Caterpillar

How the Starting System Works
The starting system converts electrical energy from the battery into mechanical energy in order to start the engine.
Illustration 1 g01073449
A basic starting system has four parts:Battery - Supplies energy for the circuitStarter switch - Activates the circuitSolenoid (motor switch) - Engages the starting motor drive with the flywheelStarting Motor - Drives the flywheel to crank the engineWhen the starter switch is activated a small amount of current flows from the battery to the solenoid and back to the battery through the ground circuit.The solenoid performs two functions. The solenoid engages the pinion with the flywheel and closes the switch inside the solenoid between the battery and starting motor, which completes the circuit and allows high current to flow into the starting motor.The starting motor converts the electrical energy from the battery into rotary mechanical energy in order to crank the engine. The starting motor is similar to other electric motors. All electric motors produce a turning force through the interaction of magnetic fields inside the motor.Starting Motor
Illustration 2 g01079926
A review of some basic rules of magnetism is needed, to understand the basic operating principles of starting motors.The following information is the basic rules of magnetism:
Like poles repel. Unlike poles attract.
Magnetic flux lines are continuous and exert force.
DuriCurrent-carrying conductors have a magnetic field that surrounds the conductor in a direction that is determined by the direction of the current flow.If a conductor has a current that has passed through the conductor, there will be a magnetic field that is formed. A permanent magnet has a field between the two poles. When the current carrying conductor is placed in the permanent magnetic field, there will be a force that is exerted on the conductor because of the magnetic field. If the conductor is formed in a loop and placed in the magnetic field, the result is the same. Since current flow is in opposite directions in the coil, one side will be forced upward while the other side is forced downward. This will provide a rotational effect or a torque effect on the coil.Starting Motor Principles
Illustration 3 g01073452
The pole pieces in the field frame assembly can be compared to the ends of a magnet. The space between the poles is the magnetic field.
Illustration 4 g01073454
If a wire (field winding) is wrapped around the pole pieces and current is passed through the wire, the strength of the magnetic field between the pole pieces increases.
Illustration 5 g01073455
If you feed current from the battery into a loop of wire, a magnetic field is also formed around the wire.
Illustration 6 g01073457
If the loop of wire is placed in the magnetic field between the two pole pieces and current is passed through the loop, a simple armature is created. The magnetic field around the loop and the field between the pole pieces repel each other, causing the loop to turn.
Illustration 7 g01073459
A commutator and several brushes are used to keep the electric motor spinning by controlling the current that is passing through the wire loop. The commutator serves