jackshaft

[ jak-shaft, -shahft ]

noun

, Machinery.

1. Also called countershaft. a short shaft, connected by belting, gears, etc., that transmits motion from a motor or engine to a machine or machines being driven ( main shaft ).
2. a shaft on which an idle wheel or fairlead turns.

jackshaft

/ ˈdʒækˌʃɑːft /

noun

1. a short length of shafting that transmits power from an engine or motor to a machine

Word History and Origins

Origin of jackshaft¹

First recorded in 1895–1900; jack ¹ + shaft

Example Sentences

The connection to the outdrive is accomplished with a long jackshaft.

From Time Magazine Archive

Just as important, no clumsy jackshaft is needed.

From Time Magazine Archive

The jackshaft places the engine in the center of the boat away from the transom, improving performance and clearing the stern area for fishing.

From Time Magazine Archive

With either power plant, the engine is separated from the sterndrive by a jackshaft, thus allowing the iron to be placed farther forward.

From Time Magazine Archive

The Mercruiser Bravo 3X outdrive, designed specifically for high-winding turbo diesels, spins a pair of counter-rotating props and is connected to the engine via an AquaDrive jackshaft that relies on constant-velocity joints to reduce noise and vibration.

From Time Magazine Archive