One of the important impact factors of the main reducer drive axle assembly quality is the control of the preload which support the initiative of a gear shaft tapered roller bearing.The assembly dimension chain is built by making the equivalent dimension which is transformed from the pre-tightening force as closed-loop

after the discussion of the axial force distribution in the assembly

the effect on bearing pre-tightening force by the change of gasket thickness.The measurement and optimization model of gasket-selection was built.A new function module where gasket types can be updated is added in software design

and a new efficient optimization algorithm of gasket-selection was proposed

and a gasket-selection soft system with an open-end gasket management module was developed.The efficiency of gasket-selection was improved greatly compared with the traditional selection methods.The study has practical significance for improving the speed of motor vehicles automated manufacturing.