There are two types of overrunning clutches currently used in China. One is to stick to the rack type, and the other is the top pin type. These two situations have their own problems. Adhering to the overrunning clutch structure is relatively simple, but the synchronization will be affected by the indexing accuracy of the cage, and it is easy to cause stress concentration in the frame to cause early fracture and reducer, which will cause the overrunning clutch to fail. The structure of ejector pin overrunning clutch is slightly complicated, but the ejector pin easily causes the cylinder effect. That is, during frequent clutch work, the roller often impacts the ejector pin. The oil in the ejector pin hole cannot be discharged in time, causing the ejector pin end to be injured. It will also lead to the early failure of the clutch. In addition, it should be noted that when designing the status of the ejector pin, the axial line of the ejector pin should pass through the axial line of the roller when the clutch is wedged. At present, domestic loaders have widely adopted two transmission assembly situations: one is a planetary hydro-mechanical power shift transmission, and the other is a fixed-axis hydro-mechanical power shift transmission.