To expand the characterization capability of big gear accuracy using on-machine measurement technology

an evaluation method of the big gear radial runout is proposed by taking advantage of tooth pitch measurement data

in which a hypothetical ball model is constructed based on the definition of radial runout specified by the National StandardinChinese

and the tooth pitch error is obtained through radius compensation after the tooth pitch measurement

and then a radial runout evaluation model is established by applying the coordinate transformation to the involute function

thus the radial runout value is calculated by solving the transcendental equation derived from the evaluation model with Newton's iterative method.According tothe measurement accuracy

comparing with the gear measurement center

the average measurement result of the present method is only a difference of 1.08 μm. According to the efficiency

only the pitch measurement process is required. The present method does not add extra metrological devices and measurement procedures

and the radial runout value can also be used to calculate the other important parameters such as cross-ball distance

which has practical engineering application value for integrating the big gear on-machine measurement equipment.