tact across the battery and motor terminals of the
solenoid, and the starter motor begins to turn the
flywheel of the engine.
When the start switch is opened, current no longer
flows through the windings. The spring now pushes
the plunger back to the original position, and, at the
same time, moves the pinion gear away from the
When two sets of windings in the solenoid are used,
they are called the hold-in winding and the pull-in
winding. Both have the same number of turns around
the cylinder, but the pull-in winding uses a larger
diameter wire to produce a greater magnetic field.
When the start switch is closed. part of the current
flows from the battery through the hold-in winding,
and the rest flows through the pull-in windings to
motor terminal. then through the motor to ground.
When the solenoid is fully activated (connection
across battery and motor terminal is complete), cur-
rent is shut off through the pull-in windings. Now
only the smaller hold-in windings are in operation for
the extended period of time it takes to start the
engine. The solenoid will now take less current from
the battery. and heat made by the solenoid will be
kept at an acceptable level.
A magnetic switch (relay) is used for the starter
solenoid circuit. Its operation electrically, is the
same as the solenoid. Its function is to reduce the
low current load on the start switch and control
low current to the starter solenoid.
The circuit breaker is a safety, switch that opens
the battery circuit if the current in the electrical
system goes higher than the rating of the circuit
A heat activated metal disc with a contact point
completes the electric circuit through the circuit
breaker. If the current in the electrical system gets
too high. it causes the metal disc to get hot. This heat
causes a distortion of the metal disc which opens the
contacts and breaks the circuit. A circuit breaker
that is open can be reset (an adjustment to make the
circuit complete again) after it becomes cool. Push
the reset button to close the contacts and reset the