The gear-axial system is the main component of heavy vehicle transmission.The transmission gear ratio and power transmit route are changed along with its shifting position.In the transmission

15 shifting are three fixed axles drive

and reverse 12 shifting are four fixed axles drive.The dynamics modeling and Matlab/Simulink moulds are built for 1 shifting and reverse 1 shifting of transmission.A method of modeling and simulation for the research of heavy vehicle transmission is offered.