Video demonstrates conveyor safety device

It also demonstrates how fitting a tension release mechanism eliminates the danger and provides the solution that protects both employees and expensive plant.

For years backstop sprag clutches have been fitted on inclined conveyors to stop them from running backwards, out of control, when stopped in a loaded condition. The same safety components are fitted to theme park rides to prevent cars from running downhill in the event of power loss. The sprags in the backstop allow a shaft to rotate in one direction by slipping, but stand up and lock immediately if it tries to turn the other way.

With inclined conveyors carrying a heavy load, such as coal, the problem arises if a blockage occurs between the lower belt and the return end shaft. The backstop sprag clutch will only allow the drive to turn in one direction, and so tension builds in the upper belt as the slack in the lower belt cannot feed back through the drive.

Fatal accidents have occurred when this obstruction is removed, as the sudden release of tension in the top belt pulls the lower belt rapidly and with extreme force around the end drum. The massive, uncontrolled force it releases has pulled workers removing blockages into conveyors, and has caused the load on the top belt to explode in all directions.

The solution to this problem is to fit one of Renold’s tension release and torque limiting backstop clutches to the gearbox. The range has been designed to enable the extreme tension in the upper belt to be safely released in a controlled way. This is achieved through the controlled friction slippage of the sprag clutch element of the backstop.

Renold’s safety tension release and torque limiting backstop clutch range, not only protects employees from dangerous accidents, but also protects plant and equipment and guards against costly downtime.