Reliability of sintered gear wheels

This paper discusses the root-strength of relatively small gearwheels with involute profile made of hardened sintered steel, Tests on a pulsator for a large number of test wheels lead to statistically secured statements about the static, the finite life and endurance fatigue strength. The calculation of the stress at failure takes place with the method of DIN 3990. The results deliver a Wohler stress-cycle diagram for a failure probability of 50%, which has to be reassessed to a stress-cycle diagram for running wheels with a failure probability of 1%. Calculations with FEM show that because of the ring design of the test wheels it is necessary to lower the fatigue strength.