A design of variable diameter wheel is proposed which aiming to solve the conflict between cross-barrier capability and structure volume.This mechanism is composed of six crank-slide linkages which simultaneously drive inner

outer and couple wheel pieces to realize variable diameter at the range of 1

2

.1.All parameters are got by establishing optimization model and physics prototype is built.Furthermore

an analysis of cross-barrier ability is conducted according the mechanics model of wheel-surface interaction based on stress distribution.The results show that bigger diameter wheel can reduce resistance as well as increase the drawbar pull of wheel and driving torque in comparison with smaller one.The form of outer wheel piece free unit under the action of soil distribution force and axle concentrated force is beneficial to the cross-barrier capability of wheel due to the character of outer wheel piece redundant degree of freed

om in the process of diameter extend

and the integrated structure performance is obtained.