A Common types are cylindrical annular clearance, conical annular clearance, and variable throttle slot cushions. At the end of stroke, the piston traps a small volume of oil, which is forced out through a narrow passage. This creates back pressure that decelerates the piston, absorbing inertia energy and preventing metal-to-metal impact. The cushioning effect ensures smooth, shock-free cylinder operation and extends component life.

A Manual adjustment uses a throttle screw to vary the orifice size, controlling cushioning intensity. Automatic adjustment relies on self-regulating mechanisms that adapt to piston speed. The key is balancing impact absorption: too tight causes harsh end-of-stroke impact and possible damage, while too loose provides insufficient cushioning. Adjust gradually while testing under no load until the piston stops smoothly without noticeable shock.

A Over-tight adjustment leads to excessive end-of-stroke impact, potentially damaging seals and components. Under-tight adjustment causes ineffective cushioning and rough operation. Correction involves adjusting the cushion valve or throttle screw to change the passage size, then testing under no-load conditions. Observe the piston's end-of-stroke behavior and fine-tune incrementally until smooth, impact-free stopping is achieved for the specific operating conditions.

A Design controls oil discharge to decelerate the piston. Cylindrical annular cushions use a straight groove; length approximately 0.5 times bore diameter, suitable for low-speed, low-to-medium pressure applications. Conical annular cushions use a tapered groove with an angle of 5–10 degrees, providing softer deceleration for higher-speed, higher-pressure cylinders. Adjustable throttle cushions use an external valve with diameter about 0.1 times bore, allowing dynamic control for frequent start-stop cycles and variable loads. Simulation tools like AMESim optimize parameters, targeting initial cushion pressure below 5 MPa and maximum pressure under 15 MPa, with deceleration time of at least 0.1 second to avoid rigid impact.

A A cushion device decelerates the piston near the end of its stroke, preventing metal-to-metal impact between the piston and end cap. It absorbs the kinetic energy of the moving mass and the fluid column, reducing noise, vibration, and mechanical stress. This protects the cylinder and connected equipment, extends component life, and ensures smooth, controlled stopping. Cushioning is essential in high-speed or high-load applications where abrupt stops would cause damage.

A Signs include a loud metallic bang at the end of stroke, vibration or shaking of the cylinder and machine, seal damage or increased leakage, and peening or deformation of the piston or end cap surfaces. Inadequate cushioning may also cause loosening of fittings and premature wear of connected components. Regular inspection of these indicators helps identify cushion failure before more serious damage occurs.

A Adjustable cushions are preferred when operating conditions change frequently, such as varying load, speed, or stroke. They allow fine-tuning of the deceleration rate to match the specific kinetic energy. Applications with frequent start-stop cycles, variable payloads, or where fine control of end-of-stroke impact is critical—such as injection molding machines and automated handling equipment—benefit from adjustable cushions to maintain optimal performance under changing conditions.

A Excessive cushion pressure causes a harsh pressure spike that can exceed the cylinder's rated pressure, potentially damaging seals, the barrel, or the end cap. It may also cause the piston to bounce back or create vibration. Over time, this leads to fatigue damage and premature seal failure. Proper cushion design limits the peak cushion pressure, typically below 15 MPa, and ensures a smooth pressure rise rather than a sharp spike.

A Regularly inspect the cushion adjustment screw and lock nut for tightness and freedom of movement. Ensure the cushion orifice is clean and free of debris that could block flow. Check the cushion sleeve or boss for wear or scoring. Replace any damaged O-rings or seals in the cushion assembly. During routine maintenance, verify the cushioning effect and readjust if operating conditions have changed. Keeping the hydraulic oil clean prevents contamination from clogging the small cushion passages.

A The cushion device generates back pressure that acts on the piston seal and rod seal during deceleration. If cushion pressure spikes too high, it can extrude or damage seals. Proper cushion design protects seals by limiting peak pressure and ensuring a gradual pressure rise. The cushion chamber should be vented or provided with a check valve to allow free flow when reversing, preventing suction that could draw in air or damage seals during startup.