Stall Torque = 20 Kg/cm. The unit is Kg*cm. And when a wheel of 4" diameter, i.e. 2"=5cm radius is directly mounted to the shaft, the "force" is 20Kg*cm / 5cm = 4kg. This means: If you put a string around the wheel and use it as winch, it could lift a weight of almost 4kg (8.8lbs) before it stalls. Motor Rated RPM = 133.