Jackshaft

A jackshaft, also called a countershaft, is a common mechanical design component used to transfer or synchronize rotational force in a machine.

Another 1872 author wrote: "Gear wheels are used in England to transmit the power of the engine to what is usually called the jack shaft.

For example, in the 1890s, the generating room of the Virginia Hotel in Chicago had two Corliss engines and five dynamos, linked through a jackshaft.

In his electric-motor driven railroad truck, the motor was geared to a jackshaft mounted between the side frames.

A sliding dog clutch inside the jackshaft was used to select one of several gear ratios on the chain drive to the driven axle.