Another museum mechanism

[Harper57]

I am looking for a way to control the speed at which a spring-loaded device returns to the original position.

How this is supposed to work is that there are panels with graphics. A question is on the left, a photo in the middle, and an open space on the right. The photo is on a fixed panel above the one below, which includes the question graphic. So the lower panel is twice as long (or wide). The bottom panel slides to the right, and the hidden answer (printed on the panel below) is revealed as the panel moves.

Once the panel is released, it should return to the left, to the reset position. Whenever I've tried this sort of thing using a spring, it snaps back too forcefully and it could cause injury. Could I use a rack and pinion to slow down the return movement?

I'm thinking that a spring is hidden underneath, which is attached to a fixed surface on the left, and to an axle of some sort on the sliding panel. This axle has the pinion, which meshes with a fixed rack below. Would this regulate the speed of the motion, or would the spring just pull the panel back at whatever speed the tension produces?

Is there a better way? Using a small door closer type gas spring?

Thanks again as always!

 

[MintJulep]

Look through the commercially available mechanisms available from

https://www.sugatsune.com/.

 

[drawoh]

Harper57,

You need a damper. There is something out there called a dashpot, which uses air as its working fluid. Try Googling it.

--
JHG

 

[MintJulep]

Or, a gas spring.

https://www.amazon.com/Mechanical-Gas-Springs/b?ie=UTF8&node=16413861

 

[Strong]

You could consider magnetic damping.

https://www.bing.com/search?q=magne...e.0.0l3.7424j0j1&pglt=299&FORM=ANNTA1&PC=U531

Damping force (motion reduction) is highest at highest velocity and diminishes with reduced speed. Many applications including braking for roller coaster!

Walt

 

[hydtools]

Look at rotary dampers.
For example:

https://www.wixroyd.com/en/page/rotary-dampers-from-wixroyd

Ted

 

[Harper57]

The solution turned out to be incredibly simple. I built a mockup with a simple carriage moving on a track, using wood and four plastic window hardware wheels from Home Depot. It took me a couple of tries. It needed a top section on the track to keep the moving piece from jumping off, since it sits at an angle. One one end there's a hole in the bottom of the unit, and through that hole a cable is attached to a counterweight on one end, and the moving carriage on the other.

When you move the carriage to the right, the weight is raised so that when you let go, gravity pulls the weight down and the cable pulls the carriage back to the starting point on the left. The trick is to balance the weight of the counterweight and the carriage so it moves slowly.

I have a video too. I hope I can post it.

 

[Harper57]

Here's the video.[URL unfurl="true"]https://res.cloudinary.com/engineering-com/video/upload/v1628039337/tips/IMG_0581_x74gqi.mov[/url]

 

[Strong]

Very nice solution! Hide the weight inside a clear PVC pipe/tube to keep curious minds from fiddling with it, but still to gain insight into how it works.

Walt