Abstract: This paper proposed a novel rail mounted three-wheel gantry to improve the structure of traditional rail mounted gantry with larger weight and higher height by the regenerative kinematic chain method. Firstly, 16 kinds of kinematic chains for three-wheel gantry were obtained by embryo graph vertex insertion method. Then according to the topological requirements of mechanism, three kinds of kinematic chains with at least two three-kinematic-pairs and one of these connects three two-kinematic-pairs was screened from above chains. Finally, the best chain was chosed based on the principle of equilibrium wheel load, a novel three-wheel gantry with balancing-linkage mechanism was obtained. The results show that compared with the traditional gantry in same specifications, the weight and design height were reduced in the prototype gantry with new topological graph. Additionally, the new topological graph could be further used in the four-wheel gantry.

Key words: kinematic chain maps; structure innovation; balance of wheel pressure; balancing-linkage mechanism