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What is a Toothed Drive Belt?

A Toothed drive belt (Also referred to as a cogged belt or a timing belt) is a fixed length flexible belt that has raised notches (referred to as teeth or cogs) spanning the width of the belt. They will sit on 2 or more pulleys that often have a matching tooth pitch and configuration.

Toothed belts are most commonly made of rubber with teeth on the inside and a flat outside. Very few are made from polyurethane or are double sided, but they do exist.

If you are looking for a belt for a power tool or garden machine, enter the model number of it into the search bar above. We try and list every belt by the model number of the machine it fits. This makes it easy for you to find and gives you the confidence of knowing it will fit.

How do I measure a Toothed Drive Belt?

Measuring a toothed belt is made up of 3 measurements. The length, the pitch of tooth and the width. Before measuring check the outside of the belt carefully as there are usually codes printed on the outside of the belts that will save you doing the following:


If the belt has snapped then lay it on a tape measure and measure it end to end. However if it is not, and it is not usable, then cut it as this method is by far the easiest and most accurate way of measuring. 

When a belt is still in use you will only be able to get a rough measurement from it. It is best to wrap a fabric tape measure around the outside of the belt. Without a fabric tape measure you will need to wrap something that doesn’t stretch around your belt and then lay that on a tape measure. This will get you to within a few mm of the true length.

Belts can be metric or imperial so it is always best to take both measurements.

Tooth Pitch

Now that you have the length, the easiest way to calculate the pitch of the teeth is to count the number of teeth on the belt. Marking every tenth tooth with a pen that shows up / marking ten teeth on a piece of paper and moving the belt round can speed up this process.

When you have the number of teeth you simply need to divide the metric length by the number of teeth and that will give you the pitch. If it is a round millimeter or .5 of a millimeter you will know that it is a metric pitch belt, if it is somewhere between that then it will be an imperial pitch that are difficult to calculate.

The most common metric pitchs are 3M (3mm), 5M (5mm) & 8M (8mm). We also stock a limited range of 2M & 4.5M. Imperial 


This is the easiest one, just lay the belt width ways on a tape measure.

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Toothed Belt Belts Drive 3M 5M XL L MXL T5 8M 4.5M Polyurethane rubber timing transmission, toothed teeth drive belt belts curvilinear trapezoidal profile measure identify cogged cog timing size pitch

What are the different tooth profiles of a Cogged Drive Belt?

There are many profiles, but the 2 most common are Trapezoidal and Curvilinear.

Trapezoidal teeth excel in transmitting forces efficiently. Nevertheless, at elevated levels of torque and speed, the blunt shape of these teeth can lead to rapid wear. Despite this drawback, trapezoidal teeth continue to be widely used, especially as the primary choice for precision conveying and linear positioning belts.

Curvilinear profile is a smooth rounded shape. Its advantages include reduced tension loss and relief from the high force concentration. However this profile has increased play between the grooves of the pulleys and teeth of the belt.

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Why has my Toothed Drive Belt failed?

There are 2 main reasons that toothed belts fail:

  1. They strip the teeth off of the belt – this can occur due to the age of a belt and general wear but be aware that it can also be because one of the pulleys has moved towards the other by a very small amount causing the belt to slip. You may find that you fit a new belt and it continues to slip and strips the teeth off the replacement belt.
  2. The belt snaps / is pulled apart – this again can occur due to the age of a belt but it is most common when the secondary pulley jams and the motor carries on pulling the belt. The teeth are so strong that it will not allow the belt to slip and instead pulls the belt apart. It is essential that you rectify the jamming problem before fitting a new belt.

How do I fit a Toothed Drive Belt?

To fit a toothed belt you will need to place it onto the smallest pulley(s) and hold it on there. Then place some teeth onto the large pulley and whilst holding the belt turn the pulleys by hand so that the large pulley takes the belt with it.

Please be aware that they are very tight belts to fit and there is normally no adjustment. DO NOT use any tools to lever the pulley on as it will damage the belt and it could snap as soon as you start the machine.

I have some information but I don't know what to do now?

When you have identified what you can please contact us by email sales@solenttools.co.uk or by phone on 02380578057 and we will do our best to help find the right belt for your machine.

Please note that we are unable to help with automotive belts.

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