jackshaft

/ˈdʒækˌʃæft/
noun
  1. A rotating shaft that transmits power from one part of a machine to another, often used in engines, vehicles, or industrial equipment.
    • The jackshaft connects the motor to the conveyor belt in the factory.
    • In a go-kart, the jackshaft transfers power from the engine to the rear axle.
    • He replaced the worn bearings on the jackshaft to reduce vibration.