×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

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

Jobs

Mechanical trail vs. Pnuematic trail

Mechanical trail vs. Pnuematic trail

Mechanical trail vs. Pnuematic trail

(OP)
All,

I'm curious about ratios of mechanical trail to pneumatic trail for performance and race applications.  I understand that self alinging torque (SAT) falls off as the limit of adhesion in sideslip is reached.  Because of this many books suggest that a good driver should sense the decrease in steering feedback and undestand this as a signal of the approaching limit.

However if one makes the mechanical trail to large this will likely drown out this delicate signal.  unfortunately the books avoid making any reccomendations on this ratio.  Should I be desiging this as 1:1 or what?  Are there any rules of thumb for this design?

Thanks
Scott

RE: Mechanical trail vs. Pnuematic trail

The pneumatic trail moves around a lot more in practice than steady state measurments indicate. If the trail goes negative then the steering wheel will go 'over centre' - which, while it might be disconcerting to a road driver should be easy to cope with for a racing driver.

So my rule of thumb would be to use the same mechanical trail as other people using the same tyre!

Kevin probably has more experience with this, but I think this is just a matter of taste, it has no objective impact on the open loop performance of the car.

Just thinking about it if the steering does go over centre then it starts to load the suspension in the opposite direction. This might induce some wooliness at around that point, which would be a bad thing.

Cheers

Greg Locock

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!


Resources