In hydraulic mechanical transmission loaders, a hydraulic torque converter can prevent an engine from stalling due to overloading of the loader during the spading process; however, the hydraulic torque converter also reduces the loader's fuel economy because of its low transmission efficiency. To address this issue, the study designs an output-power-split transmission system that is applied to a hybrid loader. The designed transmission system removes the hydraulic torque converter in the power transmission system of a traditional loader and adopts a planetary gear set with a compact structure as the dynamic coupling element, thus allowing the output power of the loader to be split transmitted. During shoveling, the loader power-split transmission system based on a planetary gear set can prevent the motor from plugging and over-burning under conditions that ensure that the traction does not decrease. In addition, the transmission efficiency and loader fuel economy are higher in the proposed transmission system than in the power transmission system of a traditional loader. The test results show that the transmission efficiency of the designed system was 13.2% higher than that of the traditional hydraulic mechanical transmission loader.

No abstract