The three parameters estimation of Weibull distribution is the first problem in gear reliability design using weibull distribution to describe random factors influencing gear reliability. The available methods of weibull distribution parameter are not applied

Because there are only average values and variances of these random factors and there are not test statistics datum of them in the available design materials. A new method of the three parameters estimation of Weibull distribution is explored. on the basis of average values and variances of these random factors. In this method

first the location parameter is determined according to possible numerical value range of a random factor

and then the shape and scale parameter are calculated using parameter equations. The method’s availability is proved by calculating examples.