Howdon Power Transmission LtdHowdon Power Transmission

Paganhill Lane, Cainscross, Stroud, United Kingdom

E: sales@howdon.co.uk  T: 01453 750814

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Torque Limiters Manufacturer | Howdon Power Transmission Ltd

Registered in England: Company No: 1316321 VAT No: GB 298 4367 03

Registered Office: Chargrove House, Shurdington Road, Shurdington, Cheltenham, Glos GL51 4GA

Torque Limiters Manufacturer | Howdon Power Transmission Ltd Howdon Power's Blog Page November Blog

Advantages of a Wedgepin over a traditional round shearpin.


In last month’s blog, we looked at the different types of torque limiters available to prevent expensive mechanical breakdown, and the benefits of fitting torque limiters to your equipment.

Made exclusively by Howdon Power Transmission since 1977, our trademarked Wedgepin torque limiter is a simple fix for the disadvantages of traditional shearpin design. Since then, it’s been used by businesses around the world to protect complex and costly equipment, and limit the associated downtime and expense of repair.

This month, we look at the advantages of the Wedgepin over the traditional shearpin.

The problem with traditional shearpins

Power transmission drives - such as those in steel rolling mills and conveyors - are at risk of unexpected jamming or stopping, and expensive damage to the power train caused by the resulting overload.

A shearpin is a replaceable pin that’s fitted to the equipment couplings to form the weakest link in the drive train. When the coupling hits a power overload, the shearpin breaks - preventing expensive damage to the machinery.

The technical bit

Shearpins usually include a centrally located annular groove that defines the point at which the pin should fail. For this to happen, the shearpin must fit within the coupling elements it connects with no clearance ・called an interference fit.

As it’s hard to achieve an interference fit with a traditional shearpin, shearpins are typically assembled with some clearance. The resultant bending that occurs mean the shearpins need to be replaced regularly as a precaution - causing unnecessary equipment downtime, and the associated costs involved.

A failed or broken shearpin can be hard to remove from the machinery it’s intended to protect, as even the smallest twist in the coupling elements can offset the axes of the respective bores. Stepped shearpins - which are smaller in diameter at one end than the other - are designed to alleviate this problem but, being harder and more costly to manufacture, they can be an expensive solution.

Advantages of the Wedgepin

The Wedgepin is a wedge-shaped shearpin, designed to overcome the problems associated with traditional shearpins. It has the same annular groove - or neck - that determines the breaking torque, but it’s designed to fit on the outside diameter, rather than the face, of the flange, which means it’s easier to access for maintenance and replacement.

The accuracy of shearpins traditionally falls within the +/- 25% range, which often rules out their use. Having carried out stringent in-house testing, and introduced different grades of materials as a result, we’ve reduced that accuracy rating to +/- 10%.

To find out more about the Wedgepin and other Howdon engineering solutions, call our sales team on 01453 750814, email sales@howdon.co.uk, or visit www.howdon.co.uk.