Abstract: For the problem of speed instability of chock carrier overloaded downhill under coal mine, this paper introduced chock carrier hydraulic system operating principle, analyzes the chock carrier overloaded the main reason for instability downhill speed, design problems chock carrier hydraulic system buffer means to solve the chock carrier overloaded unstable downhill speed protect the hydraulic system and the protection of the individual hydraulic components of the engine to improve the life of the various elements; optimized chock carrier hydraulic drive system, improve chock carrier performance, and is to provide a reference for the same vehicle traveling hydraulic system designed.