Steering Tutorial I . . I did the suspension tutorials, so I thought I might as well do some other tutorials to help out people. This tutorial explains some simple terms associated with steering, and a couple simple steering designs.
The first thing to cover are the terms "Rack and Pinion." One of the most common types of steering.
A rack is a bar with teeth on one side. There are a couple of common lego racks. The first is a 1X4 plate with teeth. The other is fairly new, or at least for me. It has the 1x4ish plate with set of teeth, but has technic holes on the end, making it easier to attach to steering arms.
Pinion is basically a gear that moves the rack side to side. Any gear will work as a pinion, but These three are the most common, or ones that work the best.
A basic rack and pinion steering system can be seen in the main photo, and also in this video. This video also has two other steering systems.
This standard method of rack and pinion is good for no suspension vehicles, or some solid axle suspension systems, such as Leaf spring, Rubberband, and Pendular. (See Suspension tutorial I)
Now you may ask "What if I want to make steering with independent suspension?" Well I have a few tips and tricks for that.
This is a steering system with independent suspension. To make steering with independent suspension, you have to have A-arms. A-arms are suspension arms usually shaped like an "A" that allow each tire to pivot up and down independent of one another. The other thing you need is some type of ball and socket pieces to allow your steering arm to move. Lego makes some different kinds of A-arms, and ball and socket pieces for this steering.
This is the steering rack, and the steering arms. Now you make one of these, and put it on your creation, but when you push the suspension down, the wheels "tow out/in". To "tow out" means that the front of the wheels are angled outward. To "tow in" means the front of the wheels move toward the center. Now this is bad, because it increases wear on your tires, and can cause steering problems. One of the best things I have found to fix this is to keep the rack/steering arms as close to to parallel with the drive axle as possible. This may sound confusing, ask questions if you don't understand.
Steering arms attached to the hub.
This is another type of steering which for the purpose of this tutorial, I will call "Lever arm" (may not be the correct term, correct me if I'm wrong) It does not require a rack, but if you are adding motors, I would suggest adding gears, as it has a tendency to move very fast.
This one is on a independent suspension system, so it has ball and socket steering arms, but the part that acutally causes the steering motion is the grey piece in the center. It is attached to a solid axle going up the center. When you turn this axle, it moves the other end of the grey piece side to side. This side to side motion is then transfered to the wheel hubs, via 1 3x5 technic L piece, and the two ball and socket arms on either side. This steering is better for smaller creations.
This, in my personal opinion, is the best way to control this type of steering. A worm gear drive. It slows the motor down enough that it turns the wheels slowly.
Steering for a pendular suspension system. Seems simple right? well there are a few things you have to think about when designing this system. Wait... before I start in on the pendular steering, that white gear is called a clutch gear, the main purpose of this gear is to keep your other gears from breaking teeth. It will turn gears, and make your steering work, but when enough resistance is applied, the shaft will spin inside the gear. This is not good for drive systems, but works good for steering systems.
This pendular suspension system is designed for a trial truck. The turn table is the part that rotates, and produces the suspension. When building a pendular suspension system, you put the steering shaft as the suspension shaft. Then when you add a motor, you find out, the wheels turn when the suspension moves. This is caused by the steering shaft not moving with suspension system. There are a couple fixes. You can mount the steering motor on the "axle" of the suspension system. There are a couple ways you can go about doing this. First you could mount the motor straight up, or off to the side. (See My Rock Crawler) Or you can mount it like I have mounted this one.
If you watched the video, you saw that at the end how this works. I attached the red piece to the motor shaft for steering, and then used two black axle to pin converters to attach the motor to the suspension axle. This is all done through the center of the turntable allowing the turn table to move, and the steering motor to stay inline with axle.
One other thing I would like to cover. If you want your steering to turn sharper, you can add double rack and pinion to your steering arms. The double pinions shown above fit with the double racks shown below, and allow the steering arm to move farther.
And this would be my WWII half track WIP. It's going to have 8 motors. Just for those of you who are curious on how it is comming, I just need to get an order of grey bricks in, and I should be set.
Thanks for looking at this tutorial, and if it helped you any, Your welcome! Oh one more thing, I'm thinking about doing a tutorial on Ackermann Geometry, a type of steering geometry. Would you like to see that?