The Double Acting Cylinder with Cushioning has a large mass or a large load and a high moving speed (> 12m / s), it has a large momentum due to a large inertial force. In this case, when the piston moves to the end of the cylinder, it will mechanically collide with the end cap, which will produce a large impact and noise, which will affect the machining accuracy and even cause a destructive accident? Therefore, in large-scale, high-speed, or high-precision hydraulic equipment, buffer devices are often provided, the purpose of which is to increase the oil return resistance when the piston approaches the terminal, thereby slowing down the moving speed of the moving parts and avoid hitting the hydraulic cylinder end cover.