Ahead in the chain game

A bespoke longwall chain tensioner is maximising the operating potential and safety characteristics of the new AFC ribbed chain.

Developed in a collaboration between Motion Australia’s fluid power business unit CRAM and consulting mechanical engineers PHD Engineering, the new tensioner has been developed to maintain the integrity and functionality of existing chain tensioning systems while taking the construction of the AFC chain into consideration. The new tensioner will also improve reliability and efficiency.

The AFC chain is structurally different in that it has a steel rib across the middle of each link, which makes it incompatible with existing chain tensioners. The new tensioner is designed to clamp over the chain, rather than the traditional hook-the-link system.

Correct tensioning of the longwall chain is vital for the smooth operation and performance of the conveyor. A hydraulic control circuit, operating through dual hydraulic cylinders, initially tensions the conveyor to a start-up force which will avoid any breakaway friction. Once the conveyor is operating at optimum efficiency, the tensioning is reset to a (generally) reduced level of force – a level that allows for normal operation and avoids overstressing any components.

At this stage of the design process, and because of their experience in the maintenance and servicing of longwall chain tensioners and particularly the cylinders used on such systems, CRAM was called in. The design of the new chain tensioner would see the level of efficient functionality retained however the new components in the system – to account for the different structure of the chain – would require more robust hydraulic components.

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