member 80 the diameter of the traction wheel 60 and the pivot radius ps of the tensioning foot 70 are selected so that the sliding friction resistance force imposed by means of the pressing member 80 upon the strap will overcome the traction wheel tangential force imposed upon the strap at the maximum available torque corresponding to the desired loop tension the novel tension control system of the present invention does not require the use of auxiliary control system such as for example a pre set tension spring a limit switch responsive to movement of the tensioning foot or an electrical or pneumatic control system responsive to an increased load upon the particular motor that is used within the tool the present invention thus eliminates the need for more complex systems the traction control system of the present invention is particularly well suited for use with tools intended to develop only relatively low levels of tension that is for example 100 pounds force tension the tension control system of the present invention is also especially useful within tools employed to tension thermoplastic strapping and join the overlapping ends of the thermoplastic strapping with a friction fusion weld wherein the weld is formed with a non planar configuration as in the embodiment illustrated in fig2 specifically with reference to fig2 it is seen that the upper strap weld pad 42 has a wavy strap engaging surface with a convex portion.