PC RV+PC worm gear reducer reducer, is reduced by the mechanical gearing motor (motor) rpm, while the inverter is to achieve the motor by changing the AC frequency (motor) speed regulation purposes. Lower motor speed by inverter, can achieve the goal of energy saving. Model: PC063,PC071,PC 080,PC 090 reduction ratio for 1/3 PC090 for 1/2.42.a. reduction ratio you around 5:1 to 3,600:1