How Stuff Works
Car owners were getting cranky before this arrived...
Fuzz talks starter motors
Steam-powered automobiles took some preparation before they were ready for the road, and so the internal combustion engines fitted to early cars seemed like a dream in comparison.
With an assistant, a spot of tweaking and a lot of fiddling with levers within the hub of the steering wheel, the motorist of the day could be off and away for a trundle within 10 minutes or so.
Simple. But that which was once a luxury soon became a chore, so restless minds turned their attention to simpler methods of engine starting, some of them rather dangerous. Enter a bright spark and the idea of using a more powerful battery to provide power to an electric starter motor, featuring a small, retractable driving pinion gear, meshing with a ring gear fitted to the engine’s flywheel. Genius.
This allowed for much easier, oneperson starting of car engines, with the driver depressing a switch in the floor to activate the starter, leaving hands free to mess about with all the other essential settings.
Further advances in automatic ignition advancing and retardation left car owners with, in comparison, virtually nothing to do but stamp on, pull or push a button and mess about with choke settings to effect start-up of recalcitrant powerplants.
In more modern times, these actions were further reduced to the idiot-proof turning of a key. And soon, even the driver will be taken out of the equation.
There have been many types of starter motor, but the basic core remained the same for 100 years or more. A basic, relatively robust and powerful electric motor was, naturally, the core of the action, but it was the engagement of the pinion gear into the flywheel ring gear that was where differences began to occur. Initially, operated by a pull switch, a lever on the motor physically pushed the pinion into mesh with the ring gear before associated electrical contacts met, supplying power to the motor, thus cranking the engine. Following on from this and commonly referred to as a ‘Bendix’ starter, further automation enabled the pinion, now set on a coarse square section thread on the starter output shaft, to be thrust rearward into mesh, and then back along the thread due to action of the engine starting, buffered by a strong spring.
Later, a development of the first method was employed, using a solenoid to thrust the pinion forward into mesh and keeping it in place until full start-up had occurred.
This was essential with diesel engines and some higher performance petrol lumps, and it basically remains common today.
‘The engagement of the pinion gear into the flywheel ring gear was where the big differences began to occur’