käsikäivitussüsteeme

Käsikäivitussüsteeme, often translated as hand-crank starting systems, are mechanical devices used to start an engine without the aid of an electric starter motor. They consist of a crank handle that engages with a pinion gear, which in turn meshes with a starter ring gear attached to the engine's flywheel or crankshaft. Turning the crank handle rotates the engine's crankshaft, initiating the combustion cycle.

These systems were prevalent in early automobiles, motorcycles, and other internal combustion engine applications before the widespread adoption of electric starters. The primary advantage of a hand-crank system is its simplicity and reliability, as it has fewer components and does not rely on a battery or electrical system. This made them ideal for situations where electrical systems might be unreliable or unavailable.

The operation of a hand-crank system requires physical exertion. The user inserts the crank into a socket, typically located at the front of the engine, and rotates it with considerable force. Care must be taken during operation to avoid kickback, where the engine fires unexpectedly and violently turns the crank backward, potentially causing injury to the operator. Many systems incorporated a dog clutch or a breakaway mechanism to mitigate this risk.

While largely obsolete in modern vehicles, hand-crank starting systems can still be found on some small engines, such as those used in lawnmowers, generators, and some classic or vintage vehicles where authenticity is desired. They represent an important stage in the development of engine starting technology.