MRO Magazine

News

Curbing killer conveyors

Wythenshawe, Manchester, UK -- A short video showing how Tension Release Backstops can prevent fatal accidents when conveyor belt jams are removed has been posted by Renold on its website. (See link to the video and a case study below).


Wythenshawe, Manchester, UK — A short video showing how Tension Release Backstops can prevent fatal accidents when conveyor belt jams are removed has been posted by Renold on its website. (See link to the video and a case study below).

For many years, standard sprag clutch backstops have been successfully used as safety devices to prevent inclined conveyor belts from running back when stopped in a loaded condition.

However, when conveyors stall because of an obstruction between the bottom belt and the return end drum, extreme tension is caused in the top belt as standard sprag clutch holdbacks do not allow the slack bottom belt to ease through the drive.

The release of these obstructions has caused fatal accidents when the uncontrolled release of tension in the top of the belt rapidly pulls the bottom of the belt around the return-end drum, with a sudden surge of extreme force.

Renold has designed a range of tension-release and torque-limiting backstops to deal with this potentially fatal force.

Fitting a Renold tension-release backstop to the gearbox ensures safe, controlled release of the built-up tension in the top belt. This is achieved through controlled friction slippage of the sprag clutch element of the backstop.

The tension-release backstop is a valuable additional safety device designed not only to increase operational safety for the workforce but also protect expensive plant against costly repairs and production downtime.

The video can be viewed here: http://www.renold.com/Products/SpragClutchFreewheels/Customised/Tension_Release_Backstops_video.asp.

CASE STUDY

Australian mining firm chooses safety product designed for inclined conveyors

Renold Clutches & Couplings of Cardiff  has supplied a safety critical Sprag Clutch Tension Release Mechanism for a new inclined conveyor built by a large mining company at the port of Cape Lambert in the Pilbara region of Western Australia.

Renold worked in conjunction with the David Brown company to design a tension release mechanism that will allow the safe removal of any obstructions at the return end of the conveyor in the event of such an obstruction causing the conveyor to stall.

Following two fatal accidents in the mining industry in 1981, it was realized the danger that existed when attempting to remove obstructions from the return end of stalled conveyors without firstly releasing the tension in the upper side of the belt.

When an obstruction at the return end of the conveyor causes the conveyor to stall then the upper belt is tight and loaded with tension while the lower belt is slack. Removal of the obstruction without first releasing the tension in the upper belt will result in the upper belt rapidly pulling the lower belt around the return roller with great force. This would obviously pose a great danger to any worker who had just removed the obstruction without a tension release mechanism to enable the task to be carried out safely.

Renold Clutches & Couplings supplied a torque-limiting safety holdback sprag clutch that allows the safe and controlled release of tension whenever maintenance work is required when the inclined conveyor is jammed when loaded.