At present Voith’s 562 Turbo Transmission Technology is used primarily in China with a total of more than 40 turbo couplings at work.

“Month after month, the armoured face conveyor systems in this country set new extraction records. Armoured face conveyors have also achieved an efficiency record in the USA, where maximum production outputs were realised under extreme conditions,” Voith said.

The TTT is also currently being used in the world’s longest AFC with an axle distance of more than 400m.

Before being installed underground at Xstrata’s Ulan mine, the system, with its unique dimensions and capacity, was tested above ground fully laden with coal. According to Voith the testing provided “impressive results”

AFCs are put through their paces at every longwall around the world, with 20 and more starting attempts not rare during a day – with the motor’s pull-out torque fully utilised.

With the TTT, Joy offers mine operators a drive system for AFCs with outputs of up to 2MW. At the heart of the drive is a fill-controlled Voith turbo coupling – which allows the system to introduce the correct amount of power to the chain.

“The power flow ranges from low for empty conveyors up to three times the nominal power if required. In the event of a chain blockage, the hydrodynamic coupling slips and protects the chain against damage,” Voith said, adding dynamic jolts during sudden blockages are absorbed by an additional Voith Safeset safety coupling.

“Other advantages of the Voith technology inside the TTT manifest themselves in the overall handling of the system. Thanks to the externally supported and hence low-wear operation of the turbo coupling there are no down times even after many years of extreme usage, and this means maximum availability – even with high starting frequencies,” Voith said.