In 1975 Hese started developing and manufacturing TT- drives for west German coal mines. At first their advantages were applied to lengthening the belt conveyor systems in the coal haulage roadways out from the longwall face. In the middle of the 1980s large conveyors began also to be equipped with TTdrives.

The advantages, Hese reports were the connection of a couple of short plants to one single belt conveyor unit, the use of smaller pulley sizes, drives and engines in spread over larger axis-centre distance, “the use of belts with lower stability and continuous belt conveyor units without intermediate transfers.

“Since the beginning of the 90s all underground large belt conveyors have been equipped with TT-drives. Furthermore, the opportunity was used to improve the capacity of old, conventional plants by implementing TT-drives without changing the existing drive and without replacing the belts.”