Abstract: The present winch may be a so-called single speed or double speed winch. The rope, which loops around a clamping roller with a looping angle smaller than 360.degree., is operated by at least one power system controlled by a control system through a spring clutch. The control system can close the spring clutch for full power transmission or open the spring clutch completely to interrupt the power train from the power system to the clamping roller. In addition the clutch may be opened partially to control the power transmission for precisely rotating the clamping roller in both rotational directions and stopping the clamping roller in any desired angular position.