... electric motors are 3 phase, 380VAC, 50 Hz, 1440 rpm. Special motor electricity systems like 110~460VAC, 50/60Hz, Single/Three Phases ... screw jack, the control of motor speed is necessary. Electric motor drive revolutions are not exceed 1800 RPM.electric screw lifts Lifting Speed ... :gear ratioT :travel stroke per revolutionExample, 4 poles(1500 rpm) electric motor,jacks model RN-0.5T-1/5(1 turn 1 ...