As it says in the title, this is a Lego City truck, which turns the front wheels by itself in the direction you push it. I got the inspiration for this creation on an official Lego channel on YouTube with video
.The vehicle is not exactly a great aesthetic achievement, but at the end it was more to the functionality than the looks.
Here are some pictures:
How it works on Lego City streets? Watch the video:
Here is the explanation:
The entire system is mounted in the lower part of the plate 4 studs wide (not shown in the picture). So the blue half-pins for attacing are mounted in to the middle circles at the bottom of an ordinary Lego plate and this amounts to width of 3 studs.
The gray parts are in this case fixed and do not move. Purple pins connect them into a whole.
The green part is responsible for a steady rotation of the black base for the wheels. Black base are connected with orange axle-pins to the gray and green parts.
Red pins secure the wheels to the black connectors.
Brown pin is added as a limiter for the wheels movement so that they are not rotating too much.