operating problems downstream the present invention obviates such problems by simulating a u201c zero mass u201d dancer vis a vis the web in contact therewith to that end a servo motor is utilized in lieu of the conventional force generators that have been used to pivot the dancer arm and tension the web any action by the web that causes the dancer arm to shift position is monitored by a position sensor typically an encoder other types of position sensors can be utilized as well for this purpose however an output signal from the position sensor is transmitted as input to a controller that signals the servo motor to correct the web tension so as to return the dancer arm to its predetermined u201c neutral u201d position the term u201c servo motor u201d as used herein and in the appended claims means an electric hydraulic or other type of motor that serves as the final control element of an automatic feedback control system for mechanical motion referring to fig1 a web tensioning system 10 is shown utilizing web tensioning device 12 engaging a tensioned segment of web 14 web tensioning device 12 includes dancer arm 16 that carries at the free end 18 thereof a dancer such as rotatably mounted dancer roll 20 that also serves as a web redirect roller fixed end 22 of dancer arm 16 is pivotably mounted to base 24 by shaft 26 which is affixed to dancer arm 16 and in turn is journaled in base 24 also fixedly mounted to shaft 26 is an encoder such as incremental rotary optical encoder 30 which serves as an angular position sensor and indicates the relative angular position of pivot shaft.