crankspindle

Crankspindle is a term found in older machine-tool literature and some niche catalogs, and it does not have a single, universally accepted definition in modern engineering. In general, it refers to a spindle arrangement that incorporates a crank mechanism to impart oscillatory or constrained motion to the spindle axis, or to a spindle that is driven by a crank-driven drive train. The exact configuration and purpose can vary by era and manufacturer.

Construction and design features commonly associated with a crankspindle include a spindle mounted for rotation in bearings, a crank pin or eccentric connected to the spindle, and a linkage (such as a rod or lever) that converts rotational input into an off-axis or oscillatory motion of the spindle. The eccentricity of the crank determines the amount and nature of the motion, which may be used to produce intermittent feed, indexing, or timed tooling action. Modern implementations are typically specialized and may emphasize reliability of the drive train, lubrication, and clamping arrangements for tooling.

Operation and function depend on the intended application. In some designs, a rotating drive shaft turns the crank, which then causes the spindle to oscillate or move with a controlled eccentricity. In other contexts, the crank mechanism serves to convert linear or rotary input into a specific motion profile for the spindle, such as intermittent feeds in early automation or cam-driven sequences in stamping equipment.

Applications of crankspindles are largely historical, appearing in older automatic lathes, textile machinery, and certain stamping or indexing machines. Today, the term is infrequent in contemporary practice, with related concepts more commonly described as crank-driven spindles or oscillating spindles. See also: crankshaft, spindle (machining).