Simple steering issue 1

[GOKNEAL]

We are manufacturing a three wheeled orthopedic scooter. As it stands, steering test show the inner wheel (on a left or right hand turn) turning in to a lesser degree then the outer wheel. What is causing this? Our tie rod mounts are not welded directly under or above the king pins. They are offset closer to the wheels. Could this impact the angle at which the wheels turn in? Changing the toe will aleviate this to a degree, but it also reduces turning radius to a large degree. Any help would be greatly appreaciated.

 

[cibachrome]

Google Ackermann steer

 

[GregLocock]

100% Ackerman will give you the lowest steering effort for a given turning circle, at low speed. If you can afford to increase steering efforts then making the wheels more parallel will improve the turning circle.

What you have is negative Ackerman, which is occasionally used, if the alternative is worse.



Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[Fabrico]

For vehicles that slide, such as in the dirt, it's often referred to as reverse Ackerman. It will do as you describe when going slow, but turns things around when you start turning right to go left.

 

[GOKNEAL]

Thanks for the fleet response. I found a great illustration at

http://www.muller.net/mullermachine/docs/ackerman.html.

We definitely had negative Ackerman. Great Forum, I will be back!!!