Caterpillar Tractor Co.

Robert J Price

Thomas C Meisel

Load skidding vehicle having a positionally biased grapple

An element (12) having a chamber (28) such as, for example, a boom (12) of an excavator (10) or a draft tube of a scraper is subject to torsional loading during use of the element (12). Torsional loading creates tensile stresses (T) on the welds (22) of the excavator boom (12), which can lead to weld failure. A method for controllably treating the metal of the element (12) includes heating the element (12) and pressurizing the chamber (28), maintaining the element (12) and chamber (28) at a preselected temperature and pressure (P.sub.1), respectively, and cooling the element (12) and depressurizing the chamber (28). The method produces residual compressive stresses (C.sub.2) in the metal, such as in the root area (23) of the welds (22) of the excavator boom (12), for increasing fatigue life under torsional loading of the boom (12).

Growing community of inventors

Peoria, IL, United States of America

Robert J Price