Bearing/Shaft Fits

I have experienced difficulty in fitting a shaft into a ball bearing/pillow block. Should it slide in quite easily ?

The bearings are manufactured with the intention that there should be some interference in the fit with a nominal sized shaft, which will give a degree of retention when the shaft is positioned. This means that some pressure may be required in the fitting process, and ideally the force on the bearing should be transmitted or resisted via the inner race, typically using, say, a sleeve, because damage may occur to the bearing if excessive axial force is applied to the outer race. The shafts which we supply are towards the negative end of the tolerance band, which will normally allow fitting with minimal interference.

It is important that the end of the shaft has a chamfer and is smooth and free from burrs to assist the initial alignment of the fit, and that the surface of the shaft is not scored or bruised.

If the shaft is cut to a shorter length to suit the application, the cut end will need to be squared, chamfered, and de-burred. To avoid damage to the surface during the cutting operation, the shaft should ideally not be held in a vice or lathe chuck with hard serrated jaws, but should be protected by using soft jaws/jaw pads.

If the shaft is introduced into the bearing with poor alignment, damage and pick-up of metal at the contact point may unfortunately make it difficult to subsequently achieve a smooth fit. Rubbing down and polishing of the shaft and bearing bore will normally improve this condition. 

Bore Size - too small

I want to order a gear/pulley/sprocket from your range, but I need it with a bore size which is larger than the standard size. Can I open up the bore by putting through a drill of the required size?

Firstly you need to carefully check that the required bore size is compatible with the size of the item, and will not destroy it, or weaken its structure.

Please note also that clamping the item and drilling out the bore may result in significant loss of bore concentricity and/or alignment. A better result will normally be achieved by putting the item up on a lathe, checking that it runs concentrically, and enlarging the bore with a drill and reamer or by boring it.

The scope for re-boring the sprockets is limited, but generally they are available with several bore size options, both metric and imperial, as standard. 

Bore Size - too big

I want to order a gear/pulley/sprocket from your range, but I need it with a bore size which is smaller than the standard size which you offer. Can you help ?

We do offer a range of bore reducers for products with metric bores, and these give options for converting many of our products to smaller bore sizes. To see the range of available sizes go to the bore reducers page

There is a facility on most of our website product pages which shows the specific bore reducer options which are available for each item.

Generally the sprockets in our range are available with several bore size options, both metric and imperial, as standard. However, further alternative sizes are potentially available by using an appropriate bore reducer.

Fixing onto Shafts

What are the methods of fixing a pulley/gear/sprocket onto a shaft ?

The products manufactured in metal are supplied with setscrews fitted as standard.

For the products which are molded in plastic, we do offer an adhesive kit for bonding them onto shafts (see ourAdhesive Kit). This will not be suitable where there is a need to remove or re-position the item, and it may then be preferable to drill and tap through the wall of the hub and fit setscrews, or drill through the hub and shaft and fit a pin.

Our sprockets have bores which are sized to give an interference fit on a shaft, which is an adequately secure fixing method, bearing in mind that this product is intended for relatively low levels of torque transmission. 

Replacements for repair of appliances, toys, machines etc

A gear in my child’s toy has broken, and attached is a photograph of it. Can you supply a replacement? I have an old ABC machine, model XYZ, on which a drive gear has failed. Can you supply a replacement?

The gears in mass-produced products are normally designed and manufactured specifically for that product, and so are likely to have a unique combination of dimensions, tooth type, number of teeth, shafting, compound gearing, etc. This unfortunately means that they are usually not readily replaceable with a standard proprietary gear, and the manufacture of a one-off replica of the original gear would probably be prohibitively expensive, in relation the value of the appliance or toy.

For this reason, it will always be worth taking trouble to check if a replacement is available from the manufacturer or his agent.

Given the huge variety of gear types in use, it is not possible to conclusively identify a particular gear type from photographs or approximate dimensions. If the damaged gear closely resembles any of the gears in our range (for which drawings and dimensions are shown on the website), it may be worth posting it to us, so that we can take detailed precise measurements and positively identify the gear type.

Our address is here. Please ensure that you include your address and contact details, so that we can return your gear to you, with our findings.

Open-length Belting

Can the open length belting be joined, so that it forms a closed loop belt (truly endless belt) of any required length ?

The open length belting cannot be successfully joined such that the necessary strength, flexibility, and tooth-form continuity would be maintained through the joint.

It is primarily intended for use in linear drive systems, as illustrated at:-

Open Length Belting

Belt Length/Number of Teeth

Can you supply belts as your standard range, but with a different length/number of teeth than those shown on your website?

If it is a size which we do not stock as standard, we will check if there is tooling to manufacture it. If so we will quote price and delivery, based on required quantity. 

Belt Width

Can you supply belts which are a different width, but otherwise the same as (Part No) on your website?
Normally we can obtain these, and will quote price and delivery, based on required quantity

Belt Stretch

Do the synchronous/toothed belts stretch, and if so by how much?

The belts are manufactured with tension cords lying within the flexible belt material. These provide the necessary tensile strength of the belts, and effectively prevent them from stretching.

If they were able to stretch, the tooth pitch would change, so that they would not remain synchronous with the toothed pulleys.

It is advisable to have some adjustment for the position of one of the pulleys in a drive system, so that the belt can be installed with moderate tension, to avoid slack running. 

Pulley Centre Distance/Belt Length

How can I find out what size(length) of belt I need to give my required centre distance with the pulleys which I want to use ?

For this, there is a Centre Distance Tool available to use on our website, by clicking on our Centre Distance Tool

There may not be a belt available which gives your exact required centre distance with the designated pulleys, so this provides a means of finding out what centre distance will result from using different combinations of pulleys and belts.

When you have picked the belt type/pitch (MXL/2,03mm or 3M/3mm) which you are using, you can then pick a belt size (number of teeth), and two pulley sizes (numbers of teeth), from our standard range. By re-calculating using different belt and pulley combinations, you can get to the centre distance which is the closest available to your requirement.

Please note that it is always advisable when using synchronous belt drives (where there is no “stretch” in the belt) to allow some adjustment on centre distance, to enable light tensioning of the belt to give smooth running.

This is typically done on a motor drive, for instance, by having slotted motor mounts.

Tensioning can be achieved by fitting a third (idler) pulley, either a toothed pulley running against the inside of the belt, or a flat pulley running against the outside, but this obviously adds additional complexity and cost. 

Belt Type

I need a belt which is not the same type as the ones you offer on the site. Can you help ?

If you can positively identify the tooth pitch, tooth form, belt width, belt length/number of teeth, and material of the belt, we may well be able to source belts to that specification, and quote you price and delivery based on the quantity you require.

If you can send us an example of the belt, we will firstly confirm the specification, and return the sample to you. Please ensure that you include your address and contact details. 

Round Belt

Can a round belt be run on Vee or square grooved pulleys?

It is not recommended, because the contact area between belt and pulley will be minimal, and the drive force reduced accordingly. Also the distortion of the belt section and repeated squeezing action may result in higher operating temperatures, and there may be increased wear rate, and reduced belt life.

Round Belt - Belt Fabrication

Can I buy a length of the belt material unjoined ?

Yes, if you tell us what length of material you require, we will quote you the price by sending you an invoice, which you can pay by credit card or your Paypal account, if you decide that you wish to proceed with the purchase.

Round Belt - Belt Length

How can I check the length of the belt which I need to order, to replace a damaged belt on an existing drive system ?

If you take a non-elastic cord of the same section diameter as the belt (e.g. rope or electrical flex) and measure the length needed to wrap round and between the pulleys, in way the same as the belt, this will give the installed length.

Using narrow string or tape will not give a correct measurement because it will lie at the base of the pulley grooves and will not be equivalent to the centre line of the belt section.

You can specify either the installed or uninstalled length when ordering, and our system will give us the correct dimension for fabrication of the belt. 

How is the length of round belts defined ?

The length of the belt is its circumference at the centre line of its section. If the belt is cut and laid out unstretched in a straight line, the end-to-end measurement will be the uninstalled length. 

What is the difference between “installed” and “uninstalled” length ?

“Installed” length is the length of the belt when it is stretched over the grooved pulleys on which it runs

“Uninstalled length is the length of the belt when it is off the pulleys and unstretched, and this is the condition in which it is fabricated.

The belt is fabricated so that the installed length is 7% longer than the uninstalled length. This puts the belt under sufficient tension to give the necessary friction drive between the belt and the pulleys.

You can specify either the installed or uninstalled length when ordering, and our system will give us the correct dimension for fabrication of the belt. 

Round Belt - Belt Fabrication

How is the belt joined ?

The belt material is aligned and clamped in a jig so that the two ends can be butt welded together, and after cooling, the excess weld flash is removed. 

Round Belt Pulley Groove

What shaped groove is correct for the round belts?

The groove should be half-round (U-shaped) in section, with a diameter to match that of the stretched belt section. This will maximize the surface area of belt in contact with the pulley groove, and hence the friction force available to drive.

motionco has a range of grooved pulleys with the correct profile, for both 3mm and 6mm diameter round belts.

For more information, go to :-

Round Belt Pulleys

General Enquiries - Further Information

Do you have a distributor/agent in my area/country, from whom I could obtain your products?

Although there are retail outlets selling some products from our range in conjunction with the other product offerings which comprise their particular market, we do not have regional authorised distributors offering our full product range.

Our focus is on providing an informative and responsive service through our website, so that our products can be readily accessed nationally and internationally, with the benefit of having the availability of all our stock, sales support and technical resource concentrated on this objective. 

Further Enquiries

Do you have a shop or premises that I can visit to view your products ?

Our premises comprise accommodation for product development and engineering, manufacturing, warehousing and dispatch, sales and marketing, and administration, but regrettably we do not have shop or display facilities which would enable customers to browse the product ranges. While it is nice to have face-to-face contact and exchange of information, the availability of such facilities would be of convenience to a relatively small section of our national and international customer base, but resourcing it would incur overhead costs which ultimately would have to be recovered in the product prices paid by everyone. We are of course happy to meet customers to discuss products and their applications, and to show them the products in which they are interested. Please contact us prior to making a visit, to ensure that we will have an appropriate member of staff available who can deal with your enquiries. Meanwhile, we do strive to make the information on our website as accessible, clear and informative as possible.