LAYSHAFT

Etymology

Noun

layshaft (plural layshafts)

A subsidiary transmission shaft.

Source: Wiktionary

Lay shaft, or Lay"shaft`, n. (Mach.)

Definition: A secondary shaft, as in a sliding change gear for an automobile; a cam shaft operated by a two-to-one gear in an internal- combustion engine. It is generally a shaft moving more or less independently of the other parts of a machine, as, in some marine engines, a shaft, driven by a small auxiliary engine, for independently operating the valves of the main engine to insure uniform motion.

Source: Webster’s Unabridged Dictionary 1913 Edition