Variable Speed Pulleys

Variable Speed Pulleys

To understand how variable speed pulleys work, it is first important to know what they are intended to do. The purpose of a variable-speed pulley is changing the revolutions per minute (rpm) on a rotating shaft—either speeding them up or slowing them down

A drive system typically consists of two pulleys: a variable-speed (mounted on the driveshaft) and a fixed diameter (mounted on the driven shaft).

The drive shaft is the power source, like a motor; it also turns at high speeds. The driven shaft requires an increase or decrease in speed—this happens by way of another component called a belt that transfers the power from one to the other.

The variable speed pulley has one or two movable flanges that are closed by spring pressure.

There are two types of variable speed pulley systems.

Movable shaft center distance:  As the moving motor base increases the distance between its two shafts, it moves a belt that engages with a variable-speed pulley.  At extreme positions of flange separation (maximum and minimum pitch diameters PD and pd), no belt engagement takes place.

Fixed shaft center distance:  A variable-speed pulley is mounted on the drive and driven shafts.  The size of the driven pulley can be adjusted manually, and a mechanical action controls its position based on rpm requirements. As the driven pulley is opened, the driven pulley will decrease in speed and the opposite, as the drive pulley is closed the driven pulley will increase in speed.

The speed range of variable-speed pulleys is nearly infinite, within standard ratio limits. Our pulleys offer an economical alternative for many applications that may not require the expense of AC/DC variable speed motors and controllers. Our variable-speed pulleys are designed for belt sizes from 1/4" V (variable) to 5/8", and horsepower ratings between 1/12 HP and 1HP.