Even before the release of the Lego 42069 set, I’ve always wanted to make a 4x4 vehicle with triangular tracks. Seeing that the season is perfect for vehicles like these (the snow!), I decided it’s finally time I make my dream come true.
The build started out with, obviously, making the 4 triangular tracks. Drive is transferred to the tracks via a large sprocket, and two small sprockets form the triangular shape. There are also two small wheels at the bottom that guide the tracks and help reduce slack. The track modules are attached to their axles with a small turntable, which allows it tilt back and forth and also keeps it well attached to prevent it from falling off. The axles are attached to the chassis with 4 suspension arms, 3 links, and 2 6.5L shock absorbers. The entire vehicle is driven by 2 L motors, with 1 per axle. A servo motor at the center of the chassis controls steering, with the front output controlling the front axle and the rear output controlling the rear. The drive/steering setup is similar to that of the 9398. Since there are no mechanical connections between the two driven axles, I added an extra M motor just to drive the V6 piston engine. The fake engine is chain-driven and can be seen by opening the hood, which can be locked in place. The model also includes Lego LEDs that light up the front lights. However, due to the bright sunlight when I filmed it, I could not demonstrate this feature.
As for the performance, the model could drive on snow pretty well. The use of tracks over wheels was advantageous in that it has better weight distribution, which reduces stress on the motor. However, since tracks are a lot less grippier than wheels, even a small obstacle means that the tracks will slip, so I had to omit differentials in the drivetrain. The lack of differentials meant that one of the tracks on each axle will be stressed when making a turn, which is why one of the tracks can be seen driving slightly tilted when making a turn. Using rubber inserts, however, may have helped with the tracks slipping, but unfortunately I do not have any at this point. The tracks also feature stoppers on the back that limit their maximum tilt, as the tracks would often tilt too far in its initial tests, especially when overcoming an obstacle.The entire model is powered by a rechargeable battery, which, despite delivering less voltage than the AA battery box, gave the model plenty of power.
Overall, I am very satisfied with the result. The model was a success not only in performance but also in aesthetics. In fact, I think this is my best-looking pickup truck model so far.
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