# What is a perfect Ackerman steering

## Draft of an Ackermann steering mechanism

You will need to make a few changes to your CAD drawing in order for it to conform to what Ackerman Theory says. I am sure once you have provided the correct information on your drawing you will find that it will work perfectly.

First determine that in your example the pivot point (turning point of your tire) is exactly on the edge of the tire. You will see that in this picture the pivot point (red arrows with the marking A. ) is clearly removed from the tire at some distance.

Second comes the point where the rotating mechanism (red arrows labeled B. ) is on board, quite a distance from the pivot points. You have this in your drawing, but I'm pretty sure it's not enough. The point at which this point should be is described as follows: When you draw a line through the pivot point ( A. ) to the center of your rear axle (red arrow with C. marked), the arm pivot point ( B. ) be somewhere on that line, but in front of the tail of the tire (I actually estimate the length of the steering arm, but that length seems logical). It has to be long enough to make the difference, but not so long to tie things together. If I were a bettor I would put it at ~ 70% of the tire radius ( NOTE: I have Tire radius said, not the swing radius). Nevertheless, the pivot point on the steering arm must be on this line.

So you won't be bothered if it doesn't exactly works over the entire turning radius. According to Carroll Smith, in Tune to Win (P. 60):

No single intersection leads to real Ackerman steering over the entire area. However, if you move the point of intersection in the longitudinal plane, you can approach the normal steering angle range.

Once you correct these things, you will find that your model is working much closer to your expectations.

As a side note, if you want technical information about it, you can interpret it mathematically. Racetech.com.au puts it (NOTE: you don't have a clear picture or I would steal it and post it here. When I have time later, I'll recreate your chart and edit this post.)

### Rocket magnet

Thanks for the answer. On point A. It makes no difference whether you move the tire along the axis. The point is that the protrusions on the axles should meet on the rear axle protrusion.

### Rocket magnet

Regarding point B: Exactly I did that and tried to explain in my question. In my diagram, I didn't draw the tires, just the hubs, and my point B is about 70% along the tire radius.

### Rocket magnet

I realize that I am not getting a perfect Ackermann steering, but what I do get even if I take the advice seems miles away from perfect, as my row of red dots shows. If you have a CAD package I urge you to try it out too and see if you can bring it closer.

### Pᴀᴜʟsᴛᴇʀ2 ♦

@Rocketmagnet ... I'll leave you a message in the chat so we don't make a mess up here. I have a few questions and requests from you, which I hope I can help you with.