Caterpillar Tractor Co.

Elwood Chaney

John W Crayton

Means are provided for maintaining a uniform height of deposited weld material in an electrical arc welding apparatus of the kind having a welding head driven by a travel motor along a juncture between two workpieces which are to be joined. A first signal, indicating departure from a desired fill depth, is produced by sensing variation of the welding current from a predetermined normal magnitude. The first signal is applied to summing junction together with a predetermined selectable reference signal of opposite polarity so that the two signals cancel out as long as the desired weld fill height is being maintained. Upon a departure from the desired weld fill height an output signal from the summing junction activates a servomotor which adjusts the speed of the travel motor as necessary to maintain the uniform weld depth. Means are further provided for assuring continuance of the welding head movement in the event that the melt should be lost because of proximity to an edge of the workpiece or because of an opening therein.

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Peoria, IL, United States of America

Elwood Chaney