A study of practical reliability estimation method for a gear reduction unit

A life and reliability model is presented for double-reduction spur gear unit. The reliability model is based on the pitting fatigue life and the Weibull distributions of the individual reliabilities of the main transmission components. The system model distribution is also a Weibull one. The gear reduction unit reliability is presented as a system life for 90 percent probability of survival of the entire assembly based on the corresponding lives for the individual components. The variation of life with load for a given reliability is modeled with a power-law relation. This model extends the Weibull reliability theory to double-reduction spur gear unit. It allows different design configurations to be compared easily from a standpoint of life at the design stage. It also provides a framework for more exact life analyses of the gear reduction units.