Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

possible to have pneumatic cylinder as a replacement for spring?

possible to have pneumatic cylinder as a replacement for spring?

possible to have pneumatic cylinder as a replacement for spring?

Hi guys,

I'm having a machine that is sort of like a cam following mechanism, which is more of copying the circumference of a mold, and spring is used to control the extending and retracting action.
The fact is i'm really not familiar with pneumatic components, i tried to use an air regulator unit connected to port A and leaving port B of the actuator expose to atmospheric pressure. then in between port A and air regulator unit, i branched out to a pressure relief valve. Problem is the relief valve is not relieving any air when retracting and hence causing pressure to shoot high everytime the actuator retracted. I'm thinking i might need a gate to control the flow from regulator and to the relief valve so that when extending the relief valve opening is closed and regulator opening is opened and vice versa.
any suggestion to the parts or combination to achieve that? or it is not possible at all??? been flipping books and surfing net, still have no clue at all.
help desperately needed.
best regards,

RE: possible to have pneumatic cylinder as a replacement for spring?

Seems like it'd be easier with a spring.  However...

The back pressure seen by the regulator depends on how much stroke the actuator undergoes during motion.  May be significant, may not.  I think the relief valve should be in parallel to the regulated supply, not in series.  During retraction, pressure builds to a point then is relieved.  Presure is applied on extension by the constant regulated supply.

You'd have to make sure all of your tubing is properly sized so that flow is not limited and motion is not optimal.  Control speed of reaction & extension with flow controls on entry & exit ports all the way around.

Easier with a...ah, never mind.

Blue Technik LLC
Virtuoso Robotics Engineering

RE: possible to have pneumatic cylinder as a replacement for spring?

OR, you could use a non-relieving regulator and put a volume chamber between it and the cylinder.  The bigger the chamber, the lower the effective spring rate of the cylinder.
DO NOT use air for pressures over ~200 psi.


Mike Halloran
Pembroke Pines, FL, USA

RE: possible to have pneumatic cylinder as a replacement for spring?

Do as Mike suggests. You do not want to be constantly consuming air when you don't have to. The other problem with air cylinders for your application is stiction of the piston seal. Friction will add to the force during retraction and subtract during extension. Rolling diaphragm cylinders perform better in this regard.

Sometimes just using a weight can be best solution for obtaining constant force.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close