About Steering

Steering is a complex part that requires some knowledge, also, you can build your models without steering. Many types of steering can be built, but we are only going to discuss the most important. Note: most steering systems shown require high gear reduction.

Rack and pinion steering

This is the most used one, but not the simplest. It consists of a rack that moves when a gear attached over it rotates on. As a result, the rack moves to one side to another depending on the rotation of the gear, called pinion. There are many ways to steer using this system. All of them use a rack beam, which is connected to links that move a steering arm, or connected to a beam which holds another one that houses the steered axle. Also, the rack beam can be connected via link or axle, to a gear block, as is done in the 9398 set.

This steering system is best suited with large models, and I recommend  to use a 12 toothed gear as the pinon than a 8 toothed one, because of its lower backlash or delay. Note: The backlash is the delay on the entire mechanism. The greater the number of gears and pulleys, the bigger the backlash.

Return to centre steering

Rack and pinion steering allows return to centre steering. As it names indicates, the steering system returns to its centre when it's released. This can be done using the x928cx1 brick, or most commonly named, hockey spring. This brick is rarely found, and builders prefer to use rubber belts to make the motor return to its initial position. Note that these mechanisms are best placed between the steering system and the motor.

Ackerman Geometry

Finally, we are going to talk briefly about Ackermann Geometry. The tyres while turning make circles with different radii, because of the width between them. This difference affects our car by increasing friction and tyre wear. Note: In Lego models this tyre wear doesn't affect our car, unless on very large and heavy models. Ackerman Steering is not necessary, is pretty much a feature. The Ackermann steering solve this problem making tyres turn at different angles. If you want to learn more about Ackermann Steering, check out this blog: Lego Ackermann Steering


Tracked vehicles steering

Steering becomes different when coming to tracked vehicles. To understand how does it work let's call left track A and right one B, so:

• - If A and B are running both with same speed and direction. The vehicle will move forward or backwards.
• - If A is running faster than B, the vehicle will turn to the right making an arc. This arc depends on the difference of speeds.
• - If B is running  faster than A, now the vehicle will turn left making an arc. As before, the greater the difference of speeds, the bigger the arc will make, and viceversa.
• - Finally, If one track (no matters which one) is moving in the opposite direction than the other track, the vehicle will turn in the place.

To make this possible, we can have one motor in each track, but this will only let you to move forward and backwards, and turn inthe place. To turn in an arc, you will need the dial remote controller to slow down the motors. The better and most complex option is to use a subtractor.

Other steering ways

It's possible to make steering systems using other ways. The key is to move the steering arm, one way is with a rack and a pinion, as explained before, but there are also other possibilities, even using a turtable brick we can make our model steer. 

Using the turntable brick

To use the turntable brick, you must divide your model in two parts, linked by the tunrtable. Driveshafts that have to travel through both parts, will need universal joints in the remaining space between them. Note: This system is quite complex and rarely used by builders.