Hello everyone,

I'd like to show my motorized version of the Model B from the Arocs 42043 set.

This is one of my favorite LEGO sets and I already tried to motorize it with Power Functions, but was not satisfied with the results. A year ago I started using RC electronics in LEGO models and recently decided to try motorizing 42043-B again.

My goal was to keep all the features of the original model, its exterior and interior and, at the same time, make the model nice to play with. The cabin remains exactly the same as in the original set, with the exception of the rear side. The chassis became 1 stud longer than the original set.

I decided to use two L motors for driving to get enough power and speed. The truck is 4x4 without a central differential or gearbox - since there is no room for them. The driving motors connected in parallel via three 16-tooth gears. I used 12:28 differentials, so the final gear ratio is 3.89:1 (16:16 -> 12:20 -> 12:28). The differentials in both axles are open. 

I especially focused on making the chassis and transmission strong and reliable - it is ready for play both inside and outside.

Original model has a standard LEGO-style fake engine, which takes up too much space. I replaced it with a compact 6 cylinder inline version. I decided not to connect the fake engine to the transmission, because it is only visible when the cab is tilted, but at the same time I wanted to keep it functional. So I connected it to a simple GeekServo motor, which can be activated remotely.

The LiPo battery (3x14500) and the on\off switch is located behind the cab in a special case built from 3x5 and 2x4 liftarms. The receiver (FlySky FS-R6b) and the ESC are hidden on the sides, in the "fuel tanks". The curb weight of the model is 1.55 kg.

The fifth wheel lock is controlled remotely using a small linear actuator and a CaDA micro motor.
 

 

Video:

 

Edited May 31, 2024May 31 by orangetrialtruck

Great job!

What ESC did you used?

Edited June 1, 2024Jun 1 by Lixander

11 hours ago, Lixander said:

Great job!

What ESC did you used?

Thank you!

I used YS-60A-RTR, bought it on Ali and soldered PF connectors.

Yes, it looks like an absolute overkill - AWG 16 wires and a massive heatsink for only two L motors :)

 

Initially, I planned to use a smaller ESC, like this one: 

But during the tests it turned out that with two L motors it could work normally for only 10-15 mins. Then the power dropped significantly (overload protection?) and I had to let it cool down for some time. Very strange, maybe my copy was defective - according to the specs everything should have worked.

Then I decided to switch to YS-60A-RTR because I had a spare one and I already had a very positive experience with it.

Edited June 1, 2024Jun 1 by orangetrialtruck

1 hour ago, orangetrialtruck said:

Thank you!

I used YS-60A-RTR, bought it on Ali and soldered PF connectors.

Yes, it looks like an absolute overkill - AWG 16 wires and a massive heatsink for only two L motors :)

 

Initially, I planned to use a smaller ESC, like this one: 

But during the tests it turned out that with two L motors it could work normally for only 10-15 mins. Then the power dropped significantly (overload protection?) and I had to let it cool down for some time. Very strange, maybe my copy was defective - according to the specs everything should have worked.

Then I decided to switch to YS-60A-RTR because I had a spare one and I already had a very positive experience with it.

So a 60A ESC...........interesting. So it is true that the PF L motors handle better these kind of ESCs than the buggy motors (I burned 3 buggy motors with a 2200mAh 25C 2S Li-Po paired with a Hobbywing QuicRun 1060 60A).

Also, it is not necessarily an overkill..........better said a measure of precaution :)))

Edited June 1, 2024Jun 1 by Lixander

I guess, you used non-original buggy motors? - original have thermal protection. I've never played with them, but I've heard many times that they are very unreliable - can burn easily. 
I use non-original L motors (standard grey clones and red ones - "enhanced") - so far so good.

11 hours ago, orangetrialtruck said:

I guess, you used non-original buggy motors? - original have thermal protection. I've never played with them, but I've heard many times that they are very unreliable - can burn easily. 
I use non-original L motors (standard grey clones and red ones - "enhanced") - so far so good.

Yup, I used rip-off motors, but I also deleted the thermal protections because the motor wouldn't run at all paired with the 60A ESC.

Edited June 2, 2024Jun 2 by Lixander

Interesting to read and a nice video as well! The addons are nicely worked away, was the left over space in the fuel tanks on the sides not a good option for hiding the battery?

On 6/4/2024 at 10:43 PM, CK28 said:

Interesting to read and a nice video as well! The addons are nicely worked away, was the left over space in the fuel tanks on the sides not a good option for hiding the battery?

Thank you!

It was my initial thought - to hide the battery in one of the fuel tanks, but, unfortunately, there were not enough space there. Perhaps choosing a battery with a different form factor could help - but I only had the 14500 batteries. 

I have only just found this, great work.