Forward always, backward never

A global mining company was having problems with its inclined conveyor because material was building up on the conveyor belt, causing it to stop repeatedly or require maintenance. Tsubaki helped them find a solution to this problem. With the BS-F backstop, which has a roller-supported clamp cage guide, operating costs were reduced.

The uncontrolled backward movement of an inclined conveyor in mining can injure people and/or cause severe damage to machinery in the event of a stoppage or blockage if the conveyor is heavily loaded. The mine operator had installed ratchet and pawl backstops in his conveyor to prevent it from running backwards when it stopped. However, due to the tooth pitch of the pawl, the locking did not occur immediately, but with a delay that caused a backlash at each stop or standstill.

This backlash caused small accumulations of material on the conveyor belt, which became increasingly jammed. This caused downtime for repair and maintenance. The mine operators turned to Tsubaki with the problem and a request to find a solution. Engineers at the leading manufacturer of drive technology products suggested replacing the existing freewheels with the BS-F backstop, which eliminates backlash.

Up to 1,000,000 Nm torque

The backstop offers high torque and can withstand overloads of up to 1,000 kNm due to its flattened sprag design. This stops the conveyor belt without delay and material accumulations are reliably avoided. 

The most important design feature of the BS series is the high-precision manufactured sprags. The BS backstops are pre-lubricated with a low-temperature grease at the factory. Due to the low contact friction in freewheeling operation, there is only slight heating. The backstops therefore operate with very low wear and energy efficiency, which gives them a long service life. In ratchet operation, the synchronous and homogeneous engagement of the sprags in the larger models is ensured by a roller-supported sprag cage guide. Combined with low speed and constant lubricant distribution, this design reduces wear on the components. 

The environmental conditions in mining are harsh. Dust and dirt can penetrate the machines and impair their mechanical function. Therefore, the developers have equipped the backstop with a flexible labyrinth seal that prevents the ingress of dust or water. A self-lubricating system with a temperature-adapted grease ensures constant lubrication. Relubrication is only necessary once a year.

Compact and flexible design

Thanks to the higher torque capacity of the BS-F freewheels compared to similar designs with integrated rollers, the overall design is correspondingly more compact. This facilitates the retrofitting of existing conveyor systems of the mine operator. Installation was quick and without any necessary modifications. The narrow I-beam fits into virtually any existing conveyor structure. Operation is also quieter compared to other backstops on the market.

After replacing the backstops, the mine operator is very satisfied, not least because the investment leads to a reduction in TCO (total cost of ownership) in the long term.