A car engine will stall-that is to say, it will suddenly stop when you do not want it to – if it is unable to provide sufficient power to overcome the load on the back wheels.
This power is provided by the explosion of the petrol and air mixture pushing down on the pistons. If the load on the pistons from the crankshaft is exerting a greater force than that created by the explosion, the pistons will not move down the cylinder and the engine will stop. This can happen if the clutch is engaged too rapidly or if the hand brake is left on.
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