Abstract: First and second tractor assemblies apply a preset tension to incremental lengths of fiber which moves continuously through the apparatus. The apparatus performs the functions of fiber pulling and non-destructive testing of all of the fiber. Each tractor assembly includes a tractor wheel and belt wheels. A belt extends around the belt wheels and engages the tractor wheel in an arc. The fiber passes between the belt and the tractor wheel in this arc. The second tractor assembly has a constant torque drive with an unloaded speed which is faster than that of the first tractor assembly. The second tractor assembly pulls the fiber thereby reducing the speed by causing the constant torque device to overload and slip.