Describe the term cushioning of cylinders. Explain with neat sketch.

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written 5.9 years ago by

teamques10 ★ 69k

• modified 5.9 years ago

Cushioning of cylinder means gradual deceleration of the piston near the end of its stroke.
It means slowing down the speed of the piston near the end of cylinder body.It is very helpful to reduce shock or impact load on the cylinder end covers specially when a heavy load is connected to the rod or the cylinder and is working at very high speed.
The cushion assembly is around 25 mm long for a standard cylinder. It consists of a small passage to allow entrapped oil to the port with cushion needle with an check valve to allow free flow of oil during reverse flow of oil during reverse start of piston travel.
The end of the cushion nose is trapped in order to enter more easily into the cushion chamber.The fluid is normally leaves through the outlet port directly, but when cushioning boss enters the recess, the fluid around the piston is trapped.
The only way the fluid can escape is through the secondary path which is restricted by a needle valve.The needle valve is adjusted so that the piston is slowed up over the last part of its stroke by a pressure build up in the fluid escaping past the needle valve.

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