Abstract: A hydraulically driven welding machine employs a closed loop control system for maintaining a constant speed of a generator. A feedback device produces a controlled frequency proportional to the actual generator frequency. The controlled frequency is compared with a reference frequency preset in the machine. Any error between the controlled and referenced frequencies is used to control a proportional flow control valve to regulate the flow of hydraulic fluid through a hydraulic motor that rotates the generator to maintain a constant generator speed under varying welding conditions. The source of the hydraulic fluid may be a hydraulic system of a motor vehicle. In an alternate embodiment, an adjustable orifice produces a pressure drop in the hydraulic system. A change in generator speed changes the pressure drop. The pressure drop is used to control a valve that diverts the proper amount of fluid flow to the hydraulic motor to maintain a constant pressure drop and thus a constant generator speed.

Abstract: A method and system for remotely controlling operational parameters of welders by communicating over a welding cable thereof with a remote device electrically coupleable between a workpiece and an electrode holder of the welder. The operational parameters include remotely enabling and disabling the welder, remotely choking the engine thereof, remotely controlling coarse and fine current adjustment, and remotely controlling other parameters otherwise controllable from a control panel of the welder.

Abstract: A gauge in the nature of a hand tool determines the radius of a rounded corner disposed between two flat side surfaces on a workpiece. As the gauge is placed in a position to straddle the workpiece, a pair of spaced, perpendicular stops on the gauge engage the flat surfaces of the workpiece to align the latter relative to the gauge. The device also includes a bar which is shiftable along a line bisecting the angle between the flat stops, and an axially shiftable arm is pivotally mounted on one end of the bar. A dial indicator having a work contactor is secured to one end of the arm, and as the work contactor is moved to slidingly traverse the convex surface of the workpiece, the indicator reveals whether the pivotal axis of the work contactor coincides with the center of curvature of the convex surface. Both the arm and the bar are shifted until the pivotal axis coincides with the center of curvature, whereupon the radius of the convex surface may be readily measured by means of a depth micrometer.