The TOTO tensioning device was designed for use with Jennmar’s Superstrand Cable systems and the TG Hollow Cable, where it will be preloaded to. The assembly can tension cables up to 8-10 tonnes using standard bolter miner rigs.

The device works by using a left-hand thread form within an assembly to tension the cable. After installation the cable is anchored at the proximal end of the device and as right-hand rotation is applied to the assembly via a dolly, it lengthens, thus tensioning the cable.

The product’s major breakthrough is the elimination of hydraulic tensioners, reducing the amount of manual handling for operators on the bolter miner and also for outbye secondary support applications.

“Existing cable tensioners can weigh 12-18 kilograms, so this product will dramatically reduce the amount of manual handling and time taken to install the cables,” Jennmar national sales manager John Naylor said.

“Many cable tensioners involve high-pressure hydraulics. Eliminating the need for hydraulically powered tensioners will eliminate the associated safety hazards and risks with the current system.”

Jennmar first developed the idea for TOTO when they saw the issues surrounding the weight of existing cable tensioning units. From a safety point of view, the company desired to move away from hydraulic systems of tensioning the cable with their reported manual handling strains and risk of hydraulic injection.

From a cost point of view, traditional tensioners sometimes require repairs, which also results in downtime.

When developing the device, Jennmar had to overcome the problem of rotation winding up energy into the wire strand.

“It had to be such that the assembly and tightening spanner used with the device would go through the gripper jaws of the bolter miners,” Naylor said.

“The size and weight of the unit was minimised while still achieving 50 tonnes strength for our cable bolts. Finite element analysis was used to achieve the preliminary designs and the usual destructive testing has followed to prove the capacity of the system.”

He said with the new device, the anchoring and tensioning of cable bolts would be as easy as installing a standard threaded rock bolt.

The device is in its first commercial production run. TOTO will be assembled onto Jennmar’s cables at its Smeaton Grange and Mackay manufacturing facilities.