Need spring to raise 225 pds 18" within 30" tube

[shanec2]

I've got two hollow pipes of 30" length each, one fits within the other, inner pipe ID is 2.9".

I need, via spring internal and/or external springs, to raise inner pipe an additional 18" with a 225 pound load atop it.

It does not have to actually raise it, just counter that 225 pound weight so it can then be repositioned easily by hand.

I only have the overall 30" of the pipes to work with for a spring inside the inner pipe pushing it up and/or springs outside the outer pipe pulling the inner pipe up.

The outer pipe has two 24" long slots running lengthwise from it's base upward to be able to connect external springs to the inner pipe within it, at it's base.

If above makes sense, I'm trying to find out if springs will do the job, be of sufficient strength and length or whether I need to abandon it all and look instead at some sort of pneumatic lift here.

Appreciate any thoughts.

- Shane

 

[MintJulep]

A simple compression spring follows F = kd

F is force, in your case 225 pounds.

k is the spring constant

d is the distance that the spring will compress

What that equation means is that any give spring will compress to one and only one height with your 225 pound load on it.

If you need to raise the weight you will need to apply force to lift. The farther you lift, the more force. Let go and it will drop back down to the equilibrium position.

If you need to lower the weight you will need to push down. Stop pushing down and it will spring back up to the equilibrium position.

In other words, a simple compression spring is not a constant force counterweight.

 

[chicopee]

I am trying to figure out that statement....."just counter that 225 pound weight so it can then be repositioned easily by hand".....How do you propose to easily reposition by hand a 225 lbs load. That statement alone confuses me about the objective of your set up. You may understand what you want to do, however, the reader like me gets a little confuse which does not take much in my case.

 

[berkshire]

Chanec2
You might look at gas springs ( Lift Struts) which have a flatter spring rate,
than a conventional spring, if you are trying to counterbalance something, they will allow you to lift and position, if you have your forces correct.
B.E.


The good engineer does not need to memorize every formula; he just needs to know where he can find them when he needs them. Old professor

 

[Occupant]

You could propably use something like the attached by mounting 3(?) of the cylinders on the OD of the large pipe and closing off the top of the small diameter pipe with a small platform that the 3 cylinders are attached to.