Timing Pulley:What Is, Types,Material,Interesting Guide

The pulley is a prevalent part of many types of machinery around us.

The timing pulley can adjust with misalignment and operate with desired timing.

This pulley is designed in such a way that it can prevent misalignment in the belt and pulley. The construction of the pulley is carried out with teeth and pockets on the periphery of the pulley hub.

The power is transferred smoothly with the mating of teeth and pockets with the belt. The teeth and pockets on this pulley differentiate it compares to others.

Types of timing pulley

The types of pulleys are differentiated by tooth profile, type of material, Dimensions, and applications.

For example, anti-backlash pulley, trapezoidal pulley, metal pulley, etc.

The pulley can be made with a variety of materials according to requirements.

The commonly used pulley is made with steel and aluminum. The pulley of other applications can be made from plastics.

Aluminum and nylon are the materials best suited for the manufacture of the timing belt pulley. This pulley required some particular type of feature to maintain a timing that can be fulfilled with these materials.

Timing pulley
Timing Belt and pulley Credit Wikipedia

What is timing pulley

The specialized pulleys are designed according to the requirement in applications.

The timing pulley contains the teeth and pockets on the periphery of the pulley hub.

This pulley transmits power by frictional force caused between the pulley and the belt surfaces. Though teeth and pockets are helpful to overcome misalignment and maintain timing, they are not used to transmit power.

The teeth on the timing pulley are engaged with the holes provided on the timing belt. The pockets on the timing pulley are mating with the lugs provided on the timing belt.

What is a timing pulley flange

The flanges are the supporting part of the pulley, as discussed below,

The function of flanges is not to allow the belt to escape from the pulley surface. It will help to maintain the lateral of the timing belt.

The flanges are mandatory on the pulley to keep the belt running on the pulley. The belt will jump out from the pulley if we do not provide proper flanges.

The flanges are made up of steel rings of various sizes. The size of the flange depends on the size of the pulley.

The flanges can be mounted on the pulley by pressing and fastening. The minor overlap is provided on the pulley to mount the flange on it.

What is the function of timing belt pulley

One can clearly define the function of the timing belt pulley with its name.

The precise homogeneous rotation between two shafts. It eliminates the slippage of the belt on the pulley.

There are no pockets or teeth over the traditional pulley. The timing belt pulley consists of teeth and pockets which not allow the belt to slip or misalign over a pulley. This pulley keeps the belt attached to the pulley surface.

1024px 2001 honda accord timing belt terabass
Timing Belt Credit Wikipedia

How does the timing belt pulley work

The working principle of the timing belt pulley is similar to a traditional pulley.

This pulley is run with friction force caused between the pulley surface and belt.

The importance of teeth and pocket is to keep the belt attached to the pulley surface. They are helpful to assist timing and reduce misalignment. The teeth and the pocket are not used to drive the pulley.              

How to design timing belt pulley

The design of the timing belt pulley can be done with a few steps.

  • Find the maximum torque for your drive.
  • Find the largest pulley dimensions and drive ratio
  • Selection of the desired tooth profile and calculate the number of the teeth required
  • Determine the teeth in mesh (TIM). Determine design torque by dividing the maximum torque with TIM
  • Find the center distance of drive and determine the belt pitch length
  • Calculate the number of teeth on the belt by the ratio of the belt pith length and the tooth pitch
  • Determine the effective tension by utilizing data of the pitch radius and the design torque
  • Calculate the required break strength by the ratio of the effective tension to strength factor
  • Selection of pulley dimension and the belt dimension based on the design torque

How to remove timing belt pulley

This pulley is required a few steps to remove from the system

The middle tensioner bolt is loosened first by pushing the spring downward. The belt is now free.

How to measure a timing belt pulley

The dimension for the timing belt pulley can be determined as below

The pulley outside diameter and pitch circle diameter charts are used to determine the dimension of the pulley.

These charts are also helpful to find the interference for system design. The pitch circle diameter is the primary variable for designing the timing belt pulley.

How do you pick a timing belt and pulley

The selection of the pulley can be done based on some factors

The material, size, and environment are three essential factors  for the selection of the pulley.

The environment factor consists of temperature variation, oil and grease contact, and chemicals and gases.

The sizing of a belt can be done by finding the designed dimensions of the pulley and belt according to applications.

The material of the belt and pulley is selected according to environmental conditions and design.