Improving the Fatigue Life of Connecting Rods in Chain Saw Engines 670009
Steps taken to improve fatigue life of connecting rods in small high performance 2-stroke cycle engines are outlined.
Design and surface treatments to improve the life of conrod bolts are covered, and the design of the cracked joint for minimum stress in the bolts is derived. Optimum case-core ratio at the conrod joint for maximum strength and good break characteristics is worked out.
The hazards of rough spot face surfaces, out-of-square bolts, tight threads, insufficient or too much initial bolt tightening torque are shown. The inadequacy of shot peening in some cases and metallurgical and forging defects are also discussed.