The Z19B expansion coupling sleeve can bear multiple loads, and its structure can be made into a variety of styles. According to the size of the installation load, multiple expansion sleeves can also be used in series. The technical points are: there is internal and external pressure between the outer ring and the inner ring The outer wall of the ring, inner and outer pressure ring is sloped, the bottom of the second ring is opposite, the inner wall of the outer ring, the outer wall of the inner ring are convex, and the concave shape of the outer wall of the pressure ring is mutually compensated, and there are gaps on the inner and outer rings. When the bolts are tightened, the inner and outer pressures move relative to each other. Under the action of the inclined plane, the inner ring begins to shrink, and the outer ring begins to expand outward to achieve the purpose of connecting the shaft and the hub. It has the characteristics of dispersing stress concentration, anti-fatigue strength, and avoiding the shaft Advantages such as disconnection. It is suitable for use when connecting shafts and hubs.