The linear spring having even forcing pull/push

[abdulbadii]

TL;DR Summary

Need a matter or configuration of linear spring direction with even forcing pull/push

How do we have linear spring direction (mostly a spherical spring) to have pull/push force evenly across some points within a range?
Or is it possible to create spring material with anomaly property capable of performing so?

 

[jrmichler]

If you want a spring that provides a constant force over a range of displacement, there is more than one way to do it.

An air spring with a large accumulator will have almost constant force over a displacement range. The gas struts used in hatchback cars are one type of air spring.

Belleville springs can be designed for constant force over part of their displacement range. A quick search found this graph that shows this:

It is possible to use a servomotor in torque mode to provide a constant force over a range of motion.

I believe that there are also complicated linkage arrangements that can do it, but have not looked for such.

And last, but not least, search constant force spring.

 

[Tom.G]

A clock spring does a pretty good job of constant force. The same approach is used in a "Product Pusher", as used in grocery stores to keep products at the front of a shelf.

At the site below, the outer end of the spring is attached to the rail. The inner end of the spring is not attached. As the vertical part is moved to the left, the spring is forced to straighten (unwind) with an almost constant force.

https://www.dgsretail.com/A0638/spring-loaded-shelf-pusher-black-2-5h-7-5w

Cheers,
Tom

 

[sophiecentaur]

TL;DR Summary: Need a matter or configuration of linear spring direction with even forcing pull/push

How do we have linear spring direction (mostly a spherical spring) to have pull/push force evenly across some points within a range?

The Fusee modification of an old fashioned clock spring uses a cylinder with varying radius and a chain to provide very even torque over the whole week's worth of winding. We have a school clock (short pendulum) and its timekeeping is really pretty fair until the time it needs winding when it speeds up by about a minute. The light chain is pretty cool but I have heard of a pierce of gut used for the same purpose.