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I am in need of a device that extends freely without much resistance but compresses slowly. I can provide a door closer analogy.The door should open fast but close slowly.... Do you think this can be achieved?

Basically my idea is to come up with a design for Wickets setup in Cricket.For people who have no idea what the game is...basically I need a setup for a 28 inch long wooden cylindrical stump of 1.5 inch radius to selfstand and withstand forces of a ball hitting it.Once the ball,say baseball, hits it, it should spring backwards and then comeback stand straight.

For this I am replacing the bottom 2 inch section with heavy metal so that it stands on its own and connecting this 2 inch section to the top one through a spring to handle the impact of ball.enter image description here

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The first design that comes to mind is a pneumatic cylinder with a large one-way valve and a slow two-way release on the back end. I've attached quick sketch below:

enter image description here

The idea here is that the big valve on top can let air in freely - letting the device extend with little resistance. Pushing the piston back in, however, the large valve closes, forcing air out the much smaller release valve on bottom. The compression rate is determined by the diameter of this valve and the force pushing on the piston.

You may have to do a little research to find out if there's something like this on the market, but if not it wouldn't be too hard to modify a single-acting air cylinder to achieve the same purpose.

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  • $\begingroup$ do you think i can find a miniture version of 2 inch radius? $\endgroup$ – raj'sCubicle Jul 6 '15 at 20:31
  • $\begingroup$ Easily, check here. That said, given your additions to your question, I'm not sure this is the right design for your problem. $\endgroup$ – Alecg_O Jul 6 '15 at 21:23
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Door closer is a great mechanism - at it's heart is a dashpot - and a check valve. If you have a check valve in parallel to the dashpot, that accomplishes the desired function. Watch below:

Dashpot and check valve

This is your mechanism at rest. You could add a spring to the top of the dashpot to force it to go back to the fully closed state when finished - but that would clutter up this illustration.

When you pull on the piece:

Pulling on dashpot

The fluid flows through the check valve, (as the flow pushes on the ball it forces the spring down, allowing plenty of flow). Note check valves work in a variety of ways, but the ball and spring is shown here. Since the fluid flows easily, the device can extend as far as the dashpot allows.

Pushing on dashpot

When pushing the mechanism back, the check valve doesn't allow the fluid to flow. As a result, the load must push back slowly as the highly viscous fluid moves around the plunger to let it sink back in to place.

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