Abstract: A method of monitoring a resistance welding system is provided. The method utilizes a sensor for isolating and determining movement of a pin that typically supports an object to be welded such as a fastener. The movement of the pin is used to determine various present welding operation parameters to reduce cycle time, and increase efficiency and quality of the weld. The present welding operation parameters are compared to learned or stored welding operation parameters, for example, to determine whether a fault should be generated or whether an acceptable weld was achieved.

Abstract: A low-impact drive unit operates by air under pressure. It includes aligned working and pressure chambers. The working chamber contains a working piston and a working piston rod extending from an end of the chamber. The pressure chamber contains a rear outer piston having a cylindrical recess and a central bore. An inner piston is located in the cylindrical recess and has a main piston rod extending through the bore, a bore in a separator separating the chambers, and is affixed to the working piston, so as to move together. The main rod has a longitudinal passage which supplies air from the pressure chamber to the back of the working piston under certain conditions. After the working piston rod contacts a workpiece, force of air pressure on all three pistons act on the working piston rod. An air return passage is provided to return the various components to their initial position after the working operation is complete.