In 1903, the first U.S. patent for an automobile electric self-starter was issued to Clyde J. Coleman of New York City (No. 745,157). He invented the self-starter in 1899, but the invention was impractical.
The license was purchased by the Delco Company, which was taken over by the General Motors Corporation. Charles Kettering at General Motors modified the self-starter, and made it practical. It was first installed on Cadillac cars in 1911. By 1920, nearly every car had a self-starter.
The self-starter is a necessity for internal-combustion engines, because the Otto cycle requires the pistons already be in motion before the ignition phase of the cycle. This means that the engine must be started in motion by an outside force before it can power itself. Originally a hand crank was used to start the engine, but it was inconvenient and rather hard work to crank the engine up to speed. For the self-starter an electric motor, called a starter motor or sometimes just plain starter, is used in place of the hand crank to put the engine into motion.
The starter, strong as it is, is not strong enough to turn the engine over so we have to gear it down, usually about 14 to 1.
If the starter works and the solenoid does not click, the solenoid might be dead or it might be that the starter button is corroded and not making good ground or the wire going to the button may be broken.
Check for continuity between the starter cable or terminal bolt, on the side of the starter, and the brush that is wired to the end of the stator coil, also called field or pole coil.
The modern starter motor is a series-wound direct current electric motor with a solenoid switch (similar to a relay) mounted on it.
Modern starter motors have a "bendix" — a gear and integral freewheel, or overrunning clutch, that enables the flywheel to automatically disengage the pinion gear from the flywheel when the engine starts.
This allowed lower current to be drawn from the battery to run the starter, and still had the initial torque needed to turn the flywheel approximately at 200 rpm.