variators

Variator is a term used for a device or mechanism that varies a parameter within a system, most often a mechanical speed or gear ratio. The word comes from the Latin variator, meaning one who varies. In engineering and related fields, variator commonly refers to the variable-pitch components of a continuously variable transmission (CVT) or other variable-speed mechanisms.

In belt-type CVTs, the variator consists of a pair of variable-diameter pulleys and a belt. Each pulley consists of a set of conical halves that move together to change the diameter engaged by the belt. By shifting the opposing pulley halves, the effective gear ratio changes continuously, allowing smooth acceleration without discrete gears. The belt transmits torque between the pulleys, and a separate differential or driveshaft delivers power to the wheels or driven load. Control systems regulate the pulley positions in response to throttle input, load, and speed.

In toroidal CVTs, a different variator arrangement uses input and output discs connected by a rotating set of rollers. The rollers are confined between the discs and can move radially, changing the contact radius and thus the gear ratio. This configuration also enables smooth endless variation of speed but relies on traction and precise roller guidance. Actuation is typically hydraulic or electromechanical, coordinated by a control unit.

Beyond CVTs, the term variator may be used more loosely to denote any mechanism that varies a parameter such as frequency, amplitude, or step size in a system. Applications appear in automotive transmission design as well as in industrial machinery and motion control. See also CVT, torque transmission, and variable-speed control.