Simple engineering design help?

Given this simple office chair lift cylinder

what simple structure(s) can be added to double its lifting height? Max lifting weight should be around 10 lbs.  The lifting motion needs to be vertical; no arc or twist.

Better yet, what existing products use a cheap pneumatic strut (besides an office chair) to lift and lower a platform in industry or in a retail product? I'm totally stuck on this cylinder doing it's normal seat lifting duties.  Mad ramblings at 1:00 am but can you help?

So you want to see a 20" lift from a 10" stroke cylinder, right?

I would think the only thing that could do that would be an arm. And if you truly can't have any arc at all, whatever your lifting will need to be able to roll or slide along some portion of the length of the arm.

The arm is also going to reduce the max weight capacity of the cylinder.

Scissor lift.

What is the budget, really? A chair is really inconvenient to adjust if you are not sitting on it.

For some simple approaches, look at IV stands, the things they hang bags of saline from.

Driven5 said:

Scissor lift.

This.  All day, part of the night 

Whats the objective?  Telescoping linear actuators are neat-o and can do maybe what you want. Does it need to remain a chair? 
 

you can use a fixed chain/rope on one side of it, pulley on the top of the cylinder and slack line on the other side. As it rises you'll have your double action. 

If  you want to double the lifting weight use two.

If you really have to stick to the office chair mechanism, you could use two - connect the top of one to the bottom of the next with a diagonal brace, now the chair has roughly twice the range. Strength would likely be reduced though. You'd definitely want the chair to rest on a bump stop connected to the lower shaft when the upper shaft is retracted, so that at ordinary seat heights the weight on the chair goes straight into the lower shaft, and the upper one is only used for raising the 10lbs to extra heights.

Edit: Also keep in mind that the relationship between the seat and the shaft would be different than stock, which might feel more tippy than you'd expect...some fab work on the bracket at the bottom of the seat may be able to correct that.

Thank you for all the responses so far. My main constraint is wanting to go up over 20 inches but all of this must fit inside a cabinet approximately 15 inches deep.  so I need some geometry to multiply the lifting height of the cylinder.  I forgot to mention the packaging dimension.

Application is not for chairs, must be cheap, and is only lifting, again, around 10 lbs.

I think I need to start researching scissor lifts. All/more input is welcome. Thanks again!

Here's some inspiration from the world of forklifts:

Uh, all of this is way too complicated. For only 10 lbs, go to the junkyard and find a hood or hatch lift strut that meets your stroke needs. 

Then order all you need on Amazon or rockauto for $7each or whatever.

Crxpilot said:

Thank you for all the responses so far. My main constraint is wanting to go up over 20 inches but all of this must fit inside a cabinet approximately 15 inches deep.  so I need some geometry to multiply the lifting height of the cylinder.  I forgot to mention the packaging dimension.

Application is not for chairs, must be cheap, and is only lifting, again, around 10 lbs.

I think I need to start researching scissor lifts. All/more input is welcome. Thanks again!

So the cabinet is shorter than the chair strut you were looking at. Definitely a job for a scissor lift.