A differential planetary gear for flip climbing transmission system which is applied to the star-climbing wheelchair is designed.According to the space limitation and the stair climbing performance requirements of climbing transmission system in the stair climbing

the tooth number distributing for each gear under transmission ratio requirements is accomplished.Furthermore

the tooth profile parameters on each gear are modified for improving the quality of the transmission.By using SolidWorks software

the three-dimensional model is established.Then impact and contact simulated analysis is carried out based on the SolidWorks Motion Plugins

and the transmission and meshing condition is verified.At the same time

the SolidWorks Motion output result is as input to the SolidWorks Simulation.Through the simulation results

the output center gear tooth can meet the carrying capacity requirements is validated.On the other hand

it also provides theoretical basis for further improve the structure design.