US ARM Y AVIATION SYSTEMS COMMAND AVIATION R&T ACTIVITY

Abstract lot each of spur gears made from a single heat of AISI 8620.MS 6274 material in the noninvolute Spur gear endurance tests were conducted to design and in the standard involute design. The investigate the surface pitting fatigue life of gear pitch diameter was 8.89 cm (3.50 in.). Test noninvolute gears with low numbers of teeth and conditions included an oil inlet temperature of low contact ratios for use in advanced applica- 320 K (116 'F), which resulted in an oil outlet tions. The results were compared with those for temperature of 350 K (170 'F), a maiTum Hertz a standard involute design with a low number of stress of 1.49 GPa (216 ksi), and a shaft speed of teeth. The gear pitch diameter was 8.89 cm 10 000 rpm. (3.50 in.) with 12 teeth on both gear designs. Test conditions were an oil inlet temperature of The work reported herein was conducted as a 320 K (116 an oil outlet temperature of joint effort of NASA Lewis Research Center, 350 K 1170.F%,a maximum Hertz stress of 1.49 GPa General Electric Co. Ordinance Systems Diision. (216 ksFT-"aid a speed of 10 000 rpm. The follow- and ITW Spiroid Division. ing results were obtained: The noninvolute gea