Abstract: A tool holder useful in storage battery assembly is disclosed whose jaws are activated by an internally located piston in one of the jaws. The jaws are mounted on a multiplicity of guide rods floatingly such that when the jaws are closed a work piece will cause them to center up over the work piece despite design variations in the work piece.

Abstract: A method and apparatus is provided for applying an electrical welding current between contacting members upon detecting a predetermined electrical resistance therebetween. Measurement current pulses are applied through the contacting members prior to the initiation of a weld current therethrough. Measurement voltage pulses, induced by the applied measurement current pulses, are compared against a reference voltage level. When the magnitude of the voltage pulses decreases to a value less than the reference voltage level, a weld signal is generated which causes the application of the weld current through the contacting members for a predetermined period of time.