The hydro-mechanical continuously variable transmission (HMCVT) is a new type transmission device, which consists of a mechanical transmission (MT) combined in parallel with a hydrostatic transmission (HST) featuring a pair of hydraulic units. The HMCVT has a continuously variable shifting ratio by the combination of HST and MT and achieves high efficiency by MT. The bench test is the important part in the research and development of HMCVT. By the bench test, these works can be carried out, such as the performance testing, the property matching of vehicle transmission, the determination of control method. In this paper, the test-bed and its control system of HMCVT assembled in DFH1302R tracked tractor are presented. The engine model and vehicle's running resistance model are established. The control principles of simulative system of engine and running resistance are studied. The communication principles of distributed control system are also discussed: the slaver computers control the throttle of engine and the eddy current dynamometer; the master computer exchanges information with the slaver computers by serial communication; the master computer collects all signals by data bus; the human-computer interaction is carried out with the virtual instrument software. The experiment results show that control test system of the HMCVT test-bed can satisfy and fulfill the test demand of the HMCVT prototype.

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