With a JIS 0 class Spur Gears of AISI9310 steel, module 4, presure angle 25 degree tooth profile, the numbers of pinion teeth 21 / gear teeth 29 carburized and tooth surface hardness HRc 59, the relationships of the load and the service life (S-N) diagram were investigated by running test on the power-circulated type gear tester.
MIL-L-23699 equivalent synthetic oil at 50° C were fed at a ratio of 0.8 l/min and circumferential velocity of 8.8 m/sec.
Also the running performance of the gears, variation of tooth profile errors, affairs of damage, etc. were examined.
Types of tooth surface fatigue mere scoring, spalling, or micropitting.
A durability limit of Hertz-stress was assumed to be around 2GPa at the load cycle of 108.