Because of the imperfection of the synchronizer design and the significance of synchronizer in caterpillar gearbox

the synchronizer mechanism and working principle are researched

Especial the four working behaviors in details.Three-dimensional solid model of the synchronizer is the first to be built up in the paper

and then the virtual prototyping is set up.Based on the correct virtual prototyping of synchronizer the working process of it is simulation with the important equation of motion.The simulation results are important to analyzing the synchronizer faults mechanics;the best matching of mechanism parameter and increasing the reliability of whose caterpillar drives system.