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What is a Poly V Drive Belt?

Poly V literally means Many V’s. This refers to the profile of the belt with many V shapes next to each other. Without looking at the profile many people say that they are ribbed or grooved drive belts as they appear to have raised ribs or cut out grooves running around the length of the belt on the inside.

These belts are most commonly made using rubber or polyurethane (Both with added strengtheners inside).

How do I measure a Poly V Drive Belt?


If the belt has snapped (and it has not stretched, melted or dis-formed) 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 will need to remove it from the pulleys and then wrap a fabric tape measure around the pulleys. Without a fabric tape measure you will need to wrap something that doesn’t stretch around the top of the pulleys (do not let it fall into the grooves) 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.

Width & Pitch

The width of poly V belts are determined by the number of V shapes (or raised ribs) rather than a measurement.

However it is important to also measure the width as this will help determine the pitch of the V (ribs). There are many pitches including PJ, PH, PK, TB2 & PU.

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.

Why has my Ribbed / Grooved Drive Belt failed?

There are 2 main reasons that toothed belts fail:

  1. The belt snaps / is pulled apart – this 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.
  2. The belt is slipping – this again can occur through age and wear on the belt 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.
  3. The belt has melted / is stuck to the pulleys – this is more typical for the polyurethane belts as they have a lower melting point than the rubber. A lot of people assume it is due to friction, but it is almost certainly that the motor is getting hotter than it should be. The heat will travel down the motor shaft and onto the pulley. It is always best to run a machine without a belt on it for at least 5 minutes to see if the pulley is heating up before ordering a new belt. If you fit a belt and the motor is overheating it will just melt the new one as well.

How do I fit a Ribbed / Grooved Drive Belt?

These belts are extremely tight to fit (due to the start up speed of the motor and the lack of teeth on the belt). They often look too small to go onto the pulleys.

You will need to put 2 of the ribs onto the smallest pulley and hold the same 2 ribs onto the large pulley (it should at least to 12 o’clock / half way onto the large pulley). Whilst holding the belt to both pulleys you will then need to turn the pulleys by hand to force the pulley to take the belt round with it. This will take a few attempts and is not always easy. Once these 2 ribs are on you can then push 1 rib over at a time whilst turning the pulleys to move the belt fully onto the pulley.

If the belt does not reach 12 o’clock / half way onto the large pulley then the belt won’t go on. At this point it is best to measure the length required (as above).

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.

What s the advantage of a Poly V Belt?

Poly-V belts, made up of triangular section longitudinal ribs, offer remarkable flexibility due to their reduced thickness, compared to Vee belts, and achieve higher peripheral speeds. This unique design allows these belts to easily wind up on exceptionally small diameters.

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