It's a typical tale, Summer starts and you are itching to rip the tarpaulin from your Lawnmower or Garden Tractor, only to find that the drive belt needs replacing! The only trouble is that the old one is worn beyond use and any identifying markings are gone. You may then go to your nearest Garden Machinery store with your mower make and model only to find that they can't match up your belt, or nearest delivery could be 2 weeks away!
This Guide shows you how to match up a belt yourself so that you know which one to get for your Lawnmower.
If you have the belt there to measure you need to check the following dimensions:
Top Section: This is the measurement across the top surface width of the belt.
Section Height: This is the measurement of the inner to the outer width.
(When taking these measurements, allow for wear and tear. An average measurement from different parts of the section height and width should be ok).
External Length: This can usually be measured with a Tailor's tape measure, or a metal flexible tape. It helps if you can make a mark with a pen or even Tip-ex where you have started to measure from. Try to be as accurate as possible with this measurement.
All Garden Machinery belts usually come in two types of thickeness: SPZ or SPA. These are termed as Wedge belts, and can be plain, cogged, or even with Kevlar cords for extra strength(Kevlar belts are usually Green or Blue in colour, and are sometimes called 'Power rated').
SPZ section drive belts typically have a Top Section width of 9.7mm, and a Section Height of 8mm.
SPA section drive belts typically have a Top Section width of 12.7mm, and a Section height of 10mm.
Now for the length measurements:
Once you have an accurate external length (and it doesn't hurt to measure again just to make sure) you can easily work out the internal length. Some suppliers may ask for either internal or external measurements.
For SPZ belts subtract 37mm from external measurement to get your Internal length.
For SPA belts, subtract 45mm.
This kind of measuring will guarantee that you get the correct size belt for your machine. Most mowers or lawn tractors have room for adjustment, usually around 1-1/2", so any deviations in measurements due to wear or stretch will not matter as long as your measurements are as near to accurate as possible.
You may find that you have no belt to measure. In this instance use a long piece of string or twine around the pulleys where the belt will travel, and then measure the groove depth of the pulley and also the groove width. By using the string you will get a pretty close idea of the internal length.(remember to mark the string off and measure to that mark with a tape)
We will have more guides to come on subjects such as Bearings, O Rings, Seals, Chains and Belts.
Here at Mayday Seals and Bearings we source and stock a large variety of drive belts for almost any purpose, so if you need something that isn't currently listed send us an Ebay message, or phone us on: 01242 241 022 and our dedicated Sales team will be only to happy to discuss any questions or requirements you may have.