CYLINDER BLOCK GP 2201952 - Caterpillar

Solenoid
Illustration 5 g00292316
Typical Solenoid SchematicThe solenoid is an electromagnetic switch that does two basic operations:
The solenoid closes the high current starter motor circuit with a low current start switch circuit.
The solenoid engages the starter motor pinion with the ring gear. The solenoid has windings (one or two sets) around a hollow cylinder. A spring loaded plunger (core) is located inside the cylinder. The plunger can move forward and backward. When the start switch is closed and electricity is sent through the windings, a magnetic field is made. The magnetic field pulls the plunger forward in the cylinder. This moves the shift lever that is connected to the rear of the plunger. The shift lever engages the pinion drive gear with the ring gear. The front end of the plunger then makes contact across the battery and motor terminals of the solenoid. The starter motor then begins to turn the flywheel of the engine. When the start switch is opened, current no longer flows through the windings. The spring pushes the plunger back to the original position. At the same time, the shift lever moves the pinion gear away from the flywheel. When two sets of windings in the solenoid are used, the windings are called the hold-in winding and the pull-in winding. Both windings have the same number of turns around the cylinder. In order to produce a stronger magnetic field, a larger diameter wire is used in the pull-in winding.When the start switch is closed, part of the current flows from the battery through the hold-in winding. The rest of the current flows through the pull-in windings to the motor terminal. The current then goes through the motor to the ground. When the solenoid is fully activated, current is shut off through the pull-in windings. Only the smaller hold-in windings are in operation for the extended period of time that is required to start the engine. The solenoid will now take less current from the battery. The heat that is generated by the solenoid will be kept at an acceptable level.Starter Motor
The starter motor is used to turn the engine flywheel fast in order to get the engine started. The starter motor has a solenoid. When the circuit between the battery and the starter motor is complete, the pinion will turn the engine flywheel. A clutch gives protection for the starter motor so that the engine can not turn the starter motor too fast. When the start switch is released, the starter pinion will move away from the ring gear.
Illustration 6 g00292330
Starter Motor Cross Section (1) Field winding assembly (2) Solenoid (3) Clutch (4) Pinion (5) Commutator (6) Brush assembly (7) ArmatureWiring Diagrams For Grounded Electrical Systems
These systems are used in applications when it is not necessary to prevent radio distortion and/or chemical changes (electrolysis) of grounded components.
Illustration 7 g00536187
Charging System With Electric Starter Motor (1) Start switch (2) Ammeter (3) Alternator (4) Battery (5) Starter motorWiring Diagrams For Insulated Electrical Systems
These systems are most often used in the following