In this post, I would like to introduce a spinning vehicle. It uses a bevel gearbox to make the wheels turn in opposite direction to generate spinning effect. Let’s take a look at the video first.
From Inspiration to Real Model
The inspiration comes from Yoshihito Isogawa’s book: The LEGO Technic Idea Book – simple machines. The author Yoshihito Isogawa wrote a series of LEGO idea books. My previous posts of Crane Model and Tricycle Model are both inspired by these books.
The key concept for this spinning vehicle is based on bevel gearbox. As shown in the below diagram, the input shaft transfers the rotation movement into two output shafts which spin in opposite directions.
So the key of the vehicle is to build such a bevel gearbox and then connect the output shafts with wheels.
Top View and Bottom View
Since the vehicle structure is simple, I will not present step-by-step instruction for the model. From the top view, we could see that the bevel gearbox structure is realized by three bevel gears. The input gear is put in the middle and connects to the motor via axis. It should mesh precisely with the two output gears.
From the bottom view, it shows only the input gear while the two output gears are blocked by the plates which are used to support the vehicle chassis. There is a third support block (in red circle) to skid on the ground when the two wheels are spinning.
Attention Points When Building the Vehicle
The vehicle structure looks simple and straightforward. The most important point is to ensure that gears are meshed precisely. In the below left diagram, you could see a semi-size yellow bush, which is put there to ensure the accurate horizontal position of input gear. Meanwhile, gears should keep a bit distance from other plates or blocks as shown in the below right diagram. Otherwise, the friction between LEGO parts will interfere the spinning of the vehicle.
Transfer Movement to Wheels
Since the horizontal position of output shaft is higher than that of wheels, they should further use compound gears (in red circles) to transfer the spinning to wheels.
You could design your own programming blocks freely. The following is just for a reference.
Easy to implement? Try it by yourself and don’t forget to enjoy the coding and have fun!
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