Adjustable speed belt gear motors are space-saving, continuously adjustable drives. In the standard version the central adjustment is manufactured with a hands wheel. Unlike inverter operation the motor power remains continuous and the torque increases if the rate of the engine drops.
The variable speed gear 
unit housing has a tested Variable Speed Belt Gear Motors Speed Reducer Gearbox symmetrical design. The adjusting pulleys have got a wedge designed symmetrical cross section with low mass. The form of the pulleys guarantees uniform flank pressure and for that reason high power transmission, also at high belt quickness.
The result is optimal control behaviour with uniform distribution of forces and minimal energy consumption.