Aim To determine efficiency of multi-range hydro-mechanical stepless transmis- sion(HMT).Methods Ageneral model of HMT was of HMT was structured.On the basis of power flow analysis, the efficiency was obtained,Results efficiency of multi-range HMT changes continuously with output speed in speed range and is higher than the highest point of the hydraulic efficiency,The volumetric efficiency can potentially result in the speed fluctuation, which can be reduced or eliminated through controlling the ratio of the displacements ofhydraulic unity properly or changing the point of range exchanging .And the mechanical- constant output torque or different output torque under the condition of constant pressure when the transmission works in different parts of a range,Conclusion The multi-range HMT is an ideal stepless transmission with high efficiency.
