Variable speed belt gear motors are space-saving, constantly adjustable drives. In the typical edition the central adjustment is made with a hand wheel. Unlike inverter procedure the motor power remains continuous and the torque boosts if the velocity of the electric motor drops.
The variable speed gear unit housing has a tested symmetrical design. The adjusting pulleys have got a wedge Variable Speed Belt Gear Motors Speed Reducer Gearbox formed symmetrical cross section with low mass. The shape of the pulleys ensures uniform 
flank pressure and therefore high power transmission, actually at high belt rate.
The effect is optimal control behaviour with uniform distribution of forces and minimal energy consumption.