Variable drive with protection against jamming for movable parts

A displacement drive having an obstruction prevention function for a movable part, comprising:

• a first arrangement for stopping one of a rotation speed of the displacement drive and a velocity of the displacement drive in response to an obstruction in the path of the movable part;
• and
• a second arrangement for reducing according to a predefined functional relationship, before a closed position of the movable part is reached and within the specific displacement range, one of the rotation speed and an output of the displacement drive to a corresponding one of a minimum rotation speed and a minimum output;
• wherein the reduction to one of the minimum rotation speed and the minimum output is performed within a specific position range, one of the minimum rotation speed and the minimum output is achieved at a specific position before the closed position of the movable part, and one of the minimum rotation speed and the minimum output is substantially constant for a finite period of time prior to the movable part reaching the closed position, and wherein the second arrangement subsequently increases one of the rotation speed and the output to a maximum value in order to provide a maximum closing force for the movable part when the movable part is less than approximately 4 mm from the closed position in an area of a rubber seal.