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!
  • Students Click Here

*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


linear cylindrical bushing

linear cylindrical bushing

linear cylindrical bushing

Is there a criteria that determines the maximum clearance between a cylindrical surface and a bore that can be tolerated without binding? I have a vague recollection about of an equation with a friction coefficient, but I cant remember the context.

Rick Fischer
Principal Engineer
Argonne National Laboratory

RE: linear cylindrical bushing

I think sufficient length to diameter ratio is mighty important in reducing the tendency to bind or jam.

RE: linear cylindrical bushing

Agreed. I am checking calculations on a device with a cylinder moving in a bore, and I need to quantify "sufficient" so we can say we looked at it and we're OK. I think I remember something from my distant past relating diameters, length, friction, etc but I cant find anything in any of my design books.

Rick Fischer
Principal Engineer
Argonne National Laboratory

RE: linear cylindrical bushing

As a rule of thumb, a length to diameter ratio greater than 2 to 1 is considered the "Long Slider" condition.

RE: linear cylindrical bushing

The 2:1 ratio is used with the length of bearing to the distance of the load from center of the bearing to prevent "stick slip". That ratio doesn't help with clearance. Many linear bearing suppliers list out both a tight clearance and a "compensated" or "free running" clearance. Which one is best depends on your application. For a carriage with 4 linear bearings, if you have precision shafting and precision alignment of the shafts to each other than all tight clearance bearings should be fine. But if there is any misalignment then having one or two of the bearings tight fit and the other two "compensated" (i.e. floating) would be better. One product that has some useful information is the Simplicity Bearings from PBC Linear.


RE: linear cylindrical bushing

It isn't in a 'design' book.
It's a sophomore kinematics problem, usually presented as an analysis of a child's toy.
There may be an image of a monkey on a stick or something like that.

Mike Halloran
Pembroke Pines, FL, USA

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!


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