Wheel loader starter LG855N:
To make an engine start it must be turned at some speed, so that it sucks fuel and air into the cylinders, and compresses it.
The powerful electric starter motor does the turning. Its shaft carries a small pinion ( gear wheel) which engages with a large gear ring around the rim of the engine flywheel.
In a front-engine layout, the starter is mounted low down near the back of the engine.
The starter needs a heavy electric current, which it draws through thick wires from the battery. No ordinary hand-operated switch could switch it on: it needs a large switch to handle the high current.
The switch has to be turned on and off very quickly to avoid dangerous, damaging sparking. So a solenoid is used - an arrangement where a small switch turns on an electromagnet to complete the circuit.
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