(ON SLIDE #206) Electrical Circuits of the Starting System. c. Any internal combustion engine must be cranked manually to start it running on its own. Early equipment was started by the driver through the use of a hand crank. A system of cranking the engine with an electric motor was developed as technology progressed. The modern electric starting system has reduced the task of starting an internal combustion engine to the turn of a key or the pushing of a button. To accomplish this task electrically, a typical starting system consists of the start and control circuits. (ON SLIDE #207) (1) Start circuit. The circuit that delivers the heavy current required to crank the engine with sufficient torque and speed to overcome the mechanical forces of friction and compression include: (a) A power source such as a battery or batteries capable of supplying the necessary electrical energy. (b) A starter motor able to change the electrical energy into the mechanical horsepower and torque required to start the engine. (c) A solenoid that closes the circuit between the motor and power source and shifts the drive mechanism into mesh with the starter ring gear on the flywheel or flex plate. (d) Heavy gauge wire to transmit the electrical energy between the power source, solenoid, and motor. (ON SLIDE #208) (2) Control circuit. One method of controlling the starter engagement is by a pushbutton on the instrument panel. Pushing the button closes the control circuit so that current can be supplied to the solenoid coil. Current practice, however, is to eliminate a separate pushbutton switch by incorporating a start position into the key switch. A relay is frequently used in the control circuit to supply current to the solenoid coils. Only
(ON SLIDE #206) c. Electrical Circuits of the Starting System. Any internal combustion engine must be cranked manually to start it running on its own. Early equipment was started by the driver through the use of a hand crank. A system of cranking the engine with an electric motor was developed as technology progressed. The modern electric starting system has reduced the task of starting an internal combustion engine to the turn of a key or the pushing of a button. To accomplish this task electrically, a typical starting system consists of the start and control circuits. (ON SLIDE #207) (1) Start circuit. The circuit that delivers the heavy current required to crank the engine with sufficient torque and speed to overcome the mechanical forces of friction and compression include: (a) A power source such as a battery or batteries capable of supplying the necessary electrical energy. (b) A starter motor able to change the electrical energy into the mechanical horsepower and torque required to start the engine. (c) A solenoid that closes the circuit between the motor and power source and shifts the drive mechanism into mesh with the starter ring gear on the flywheel or flex plate. (d) Heavy gauge wire to transmit the electrical energy between the power source, solenoid, and motor. (ON SLIDE #208) (2) Control circuit. One method of controlling the starter engagement is by a pushbutton on the instrument panel. Pushing the button closes the control circuit so that current can be supplied to the solenoid coil. Current practice, however, is to eliminate a separate pushbutton switch by incorporating a start position into the key switch. A relay is frequently used in the control circuit to supply current to the solenoid coils. Only
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