4 positioned above the surface of beam 1 the mounting brackets 11 15 16 and 17 are affixed to the backside of the slay beam 1 so as to hold the tensioning device in the thread 39 s travel path tensioner 6 includes a motor 12 such as a stepper or servo motor a torque sensor 13 connected to the motor 39 s shaft and tensioner arm 14 mounted on the torque sensor 13 for holding the gripper 18 with the gripper 18 open the tensioner is in the rest position to enable the shuttle 5 to pass underneath it recognition that a shuttle 5 has passed sensor 8 of fig1 activates the motor 12 and begins rotation of arm 14 when the tensioner passes position x in fig2 a controller signals the gripper 18 to close as soon as the gripper has closed the tensioner 6 starts to stretch and tension the thread the position y where the gripper is fully closed is generally perpendicular to the thread path of travel the final tension position z is where motor rotation stops because either the servo motor reaches an electric resistance equal to the set resistance corresponding to the desired tension or the torque sensor.