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The Electrical System:
The Starter
 At one time or another, most of us have seen pictures of vintage cars that had an external handcrank located at the front of the car. You can imagine how inconvenient it would be if every time you needed to start your car you had to run to the front of the car and manually crank the engine. In fact, it was not unheard of for bones to be broken if the engine kicked back. Image Right: Modern Electric System
In 1912 inventor extraordinaire Charles Kettering invented the electric starter.
Within four years over 95% of the manufactured automobiles were equipped with the new electric starters.
The electric starter is activated by turning the ignition key. When the key is turned, a switch completes an electrical circuit from the battery to the starting motor. An electrical switch or solenoid causes a plunger to extend a small gear, called a pinion gear until it meshes with the crank shaft’s flywheel. The starting motor’s pinion gear engages the flywheel and causes it to turn until the engine can operate under its own power.
When the engine starts the key is released causing the circuit to be broken and the plunger retracts, disconnecting the pinion gear and starting motor from the flywheel.
 The starter converts electricity to mechanical energy in two stages. Turning on the ignition switch releases a small amount of power from the battery to the solenoid above the starter. This creates a magnetic field that pulls the solenoid plunger forward, forcing the attached shift yoke to move the starter drive so that its pinion gear meshes with the engine's crankshaft flywheel. When the plunger completes its travels, it strikes a contact that permits a greater amount of current to flow from the battery to the starter motor. The motor then spins the drive and turns the meshed gears to provide power to the crankshaft, which prepares each cylinder for ignition. After the engine starts, the ignition key is released to break the starting circuit. The solenoid's magnetic field collapses and the return spring pulls the plunger back, automatically shutting off the starter motor and disengaging the starter drive.
When the starter is not in use, the drive unit is retracted so that its pinion is disengaged from the flywheel. As soon as the starter is activated, the forward movement of the solenoid plunger causes the shift yoke to move the drive in the opposite direction and engage the pinion and flywheel. The pinion is locked to its shaft by a clutch that unlocks if the engine starts up and the flywheel begins turning the pinion faster than its normal speed. By allowing the pinion to spin freely for a moment, the clutch protects the motor from damage until the drive is retracted. |
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1. Electrical System
2. The Battery
4. The Alternator
5. The Voltage Regulator
6. Lighting
7. Lighting System Basics
8. Interior Lights
9. Voltage
10. Turn Signals and Hazard Lights
11. The Horn
12. Windshield Wipers
13. The Defroster
14. Electrical Symbols
15. Types Of Electrical Circuits
16. Electrical Circuit Defects
17. Introduction To Automotive Batteries
18. Battery Construction
19. Battery Operation
20. Specific Gravity
21. Voltage And Capacity
22. Battery Ratings
23. Testing Automotive Batteries
24. Preventive Maintenance Of Batteries
25. Optical Battery & Antifreeze Tester
26. Measuring Specific Gravity With The Optical Battery Tester
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