Cushioning, or soft start as it is sometimes referred to, is used to slow down a hydraulic cylinder, by reducing the speed of a piston at the end of its stroke, or before it meets the end cap. This method is generally used in double-acting cylinders, for heavy duty applications that use a lot of kinetic energy.
Cushioning is commonly fitted to both the rod side and full-bore side of a cylinder, to bring the final movement of the rod to a stop. This prevents the piston from slapping against the back of the gland and the end cap of the cylinder when opening and closing.
The ultimate purpose of using a cushioning method is to avoid damage to the piston, which could occur when a high oil volume is applied to a hydraulic cylinder.
Other advantages of using a cushioning method are that it extends the life of the cylinder by reducing the impact of vibrations, as well as reduces any excessive audible noises.
Hydraulic cylinders operate by pumping a medium into the cylinder causing the piston to extend or retract to the end of its stroke.
A cushioning device works on the principle of forcing a small amount of the cylinder fluid through or over a smaller diameter / orifice which is usually present to the front or rear of the piston, as it comes to the end of its travel.
The cushioning device therefore restricts the flow of fluid to the back of the neck gland or base of the cylinder, which ultimately slows down the stroke of the cylinder as the fluid cannot go anywhere else, apart from through the tolerance aperture of the gland, resulting in slowing down the stroke to a stationary finish.
It is always best to decide whether to fit a cushioning device at the initial design and build stage of cylinder, as retro fitting can be a very costly.
Should you want any further advice on cylinder design and cushioning components, please contact our knowledgeable and helpful team today.
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