a short length of shafting that transmits power from an engine or motor to a machine
jackshaft in American English
(ˈdʒækˌʃæft, -ˌʃɑːft)
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 (distinguished from main shaft)
2.
a shaft on which an idle wheel or fairlead turns
Word origin
[1895–1900; jack1 + shaft]This word is first recorded in the period 1895–1900. Other words that entered Englishat around the same time include: calling card, cutback, flamenco, freewheel, hit-and-run