Understand the process of timing pulley and it's belt sizing process
06 Sep, 2021

Understanding the timing pulley and belt sizing process

The timing pulley gets used in various manufacturing units. Timing pulleys mainly link two simultaneously rotating shafts. The timing pulley and timing belts come with teeth and lock the rotation of both shafts but keep the entire system truly functional and smooth. Due to the teeth facility, the timing pulley can easily eliminate slippage out of the equation.

Sizing of Belts

Timing pulley and belt size are very important when it comes to enjoying the maximum possible benefits. There are several variables you need to consider to calculate the perfect size of the pulley belt. Width, no of teeth, material, and so many other things are there to consider when it comes to picking a perfect pulley belt. Apart from this, there are some important factors that must consider such as shaft speeds, power transmission, working environment, and other important factors based on the situation.

Rotation Ratio of Timing Pulley

Timing pulley and belt will always come with a rotation ratio between two linked shafts. According to the shaft rotation speed, the ratio will be decided. Enabling the right rotation ratio is important to calculate the teeth of the timing pulley.

Calculating an Ideal Belt Length

Designing as well as figuring out the distance between the centers of two connected shafts and pitch diameters are important in order to create an ideal timing pulley and pulley belt size. The pulley manufacturer will mention the pitch diameter. The manufacturer will help you in choosing the ideal pulley belt length. But if you are making an online purchase, you have to follow some formulas to get your ideal length pulley belt to support your system.

The formulas are:

2C + [{π (D1 + D2)}/2]


2C + [{π (D1 + D2)}/2] + [(D1 – D2)²/4C] The second formula offers more accurate results according to the experts and manufacturers.

·         C stands for the center to center distance between the shafts that are intended to be connected.

·         D1 stands for pitch diameter of large timing pulley

·         D2 stands for pitch diameter of the small pulley

If there is no pretension on the belt, these formulas are not going to work. The recommended pretensions range from one to eight percentages. Belts are built in certain lengths and that’s why you may need to slightly adjust the shaft spacing. Or you may need to enable changes in pulley diameters in order to find which way works better for you.


From this brief discussion, you will get the most effective information and belt length calculation formulas. You can try and let us know your experience.

Get in Touch

Connect with us if you wish to discuss your next batch of job or next project

Need Help?