What Is a Timer Pulley?

Mark Wollacott
Mark Wollacott
Woman holding a book
Woman holding a book

A timer pulley is used to reduce the amount of force needed to move an object. It differs from a normal pulley because its rim has teeth instead of a smooth surface. These teeth lock into receptors in the belt or chain connecting the pulleys together.

Pulleys are a series of two or more wheels connected by a single belt. This belt can be made of fabric, rope, chain or cable. There are a number of types of pulley and pulley systems. As well as the timer pulley, there are also smooth, grooved and variable speed pulleys.

Regardless of the type of pulley used, there are three basic types of pulley system. Fixed pulleys keep the axle in situ, keeping the machine stable, but without amplifying its power. Movable pulleys allow the axle to move in space, and this doubles the machine’s power. A compound pulley mixes fixed and movable elements and can allow for more than double power when used.

The timer pulley works by reducing force and increasing the distance over which an operation can be done. It does not alter the work being done itself. Each additional pulley, if placed in the right position, further reduces the amount of force required to to the job. The pulleys and belts are kept weightless to reduce the amount of friction produced. Any friction will reduce the amount of energy transferred from them to the work being done.

Apart from changes in size, a timer pulley comes in two basic forms: with or without flanges. A flange is a protective rim or lip around either side of the pulley’s rim. The primary function of the flange is to prevent the belt from slipping off the pulley. A flange is not required for small distances, as the timer pulley’s teeth provide a good enough grip. They are required when the pulleys are vertically arranged or when the distance between the pulleys is greater than eight times the diameter of the smallest pulley.

The main advantage of the timer pulley is its positive grip. The presence of interlocking teeth allows for a steady and smooth operation of the machine. They also reduce the noise caused when the machine is in operation. They are also capable of running at faster speeds than regular pitch pulleys. On the downside, timer pulleys are initially expensive to set up.

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