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

whose in control

whose in control

whose in control

If you have a solid rear wheel drive axle controled by skewed upper,lower four link control arms and add a panhard rod in a effort to lower the rear roll center who is in control? At some point would a geometric bind be reached and cause heavy loading of the tires by locking the travel?

RE: whose in control

Yes, it is quite easy to arrange a 5 link system like that so that it is not capable of free motion - in fact many modern suspensions on the road today would be locked up but for the compliance in the rubber bushes.

This is not a good idea for live rear axles in partiuclar, ours are designed so that kinemtaically they are linkages, not structures.

The only way to analyse these locked up linkages properly is to do a compliance study, or start making approximations.


Greg Locock

RE: whose in control

I'm completely in agreement with Greg.

People have added PHB's to triangulated 4-links, but I think the best results came when the PHB wasn't trying to force a lower roll center.  The greater the amount that you try to lower the RC the more the splayed uppers will fight it.  In those cases, the gain was in improved lateral axle location rather than in RC location.

People have also added a PHB and then either removed one of the splayed uppers or replaced its bushings with soft foam for a so-called "poor man's 3-link".  This better accommodates lowering the RC, but I'm not at all sure what it would "feel" like to drive as the remaining upper is still splayed.

Relatively recently, a few real 3-link conversions have been developed within the aftermarket (or in some cases perhaps still under development).  Unless you're competing in a class where such a mod is not permitted, this would be a better way to go.


RE: whose in control

Thanks for the reply's.

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


Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

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