an initial position shown in full lines away from each other each by a distance l into a final position as shown in dot dash lines thereby extending rope 9 by a length of four times distance l in another embodiment of the invention the tension device may include only one movable sheave rope tensioning device 8 fig1 and 2 includes a stationary frame 10 supporting two rodless pneumatic cylinders 14 and 15 each cylinder 14 and 15 having a movable piston not shown to which sheave support 13 is connected sheave supports 13 are adapted to support rotatable sheaves 11 and 12 e g by antifriction bearings in yet another embodiment of the invention rope tensioning device 8 will be positioned in a paper making machine in which rope 9 is used in the paper making machine the tensioning device may be arranged horizontally as shown in fig1 vertically upside down or in any other orientation two or more tensioning devices may be combined in order to tension a twin rope system or a three rope system usually each rope forms an endless loop traveling at the operating speed of the paper making machine at the infeed end of rope tensioning device 8 close to the incoming run 9 a of rope 9 rope.