Teo LEGO Technic

Foarte tare! Do you have any videos of it driving? Also, I can't really see from the photos what parts you're using on the front for the driven independent suspension, is that the old CV joint? Did you have any issues with it popping out under the power of the buggy motors?

Awesome take on this Audi! One of my co-workers showed me this model this past summer, and I've been a big fan of it since, glad to see it built in Technic

Wow, that's an impressive improvement! I'm especially a fan of what you've done with the rear. The brick-built panelling covering the rear wheels improves the shape a lot, and by reducing the distance between the fender piece and the panel above it you've made the car look much more put together. Great work!

Awesome, appreciate it!

Yeah totally! I wonder if it isn't worth having a thread somewhere specifically for advertising LEGO-related events, it'd be nice to gather more people here in Canada. Anybody know how to go about that? @Milan Sorry to bother you, perhaps you have a suggestion?

Good point, that's definitely the case. I was thinking about the question of diffs vs. no diffs more generally, not for this specific axle.

Hey everyone! For the first time Toronto, Canada is going to have a Truck Trial race . This is my WIP topic for my entry - a 6x6 truck based on the Praga trial truck, as seen below: The goals for this model are as follows: Performance prioritized over looks - a bulkier or uglier design that is more robust will be favoured over a cleaner design. The primary goal is the best possible offroad performance Highly robust transmission and steering - I want to make sure that none of the mechanical functions are going to fail under pressure 6x6 drive with diff locks on all 3 axles 2-speed gearbox Winch My plan for this MOC is to reuse many of my successful design ideas from my most recent Unimog U5000, but with a couple of key improvements: Reusable ideas Robust transmission setup - by gearing down the transmission close to the wheels, pressure is reduced on sensitive components such as universal joints and differentials Gearbox - the gearbox design, based on @Sariel's heavy-duty gearbox idea, was very reliable Pneumatic diff lock mechanism - this was also working very well Features needing improvement Steered hub robustness- the steering hubs on the Unimog were too weak Steering strength - the small linear actuator used for steering turned out to be too weak under the weight of the finished model, as @nerdsforprez originally anticipated (if only I had listened ) The first decision I have to make is how to power the model. Although I was happy with the power output of 2 XL motors with BuWizz on the Unimog, this MOC will be even heavier, so I can either gear the motors down further or power it with 4 XL motors and 2 BuWizz (which is the more fun but more expensive option). I also have to decide how I am going to build the robust front axle I want. I'm leaning towards using the LEGO Unimog portal axle hubs. Despite their poor turning radius, they are probably going to be more robust than any custom portal axle I could possibly build, but if anyone disagrees I would love to hear your arguments . As for the steering mechanism itself, I am thinking of either using a large linear actuator, although it will be difficult to fit in the limited space without limiting turning radius, or alternatively, a large rack and pinion with a worm gear setup. I am leaning towards the latter, but this will be a bit more tedious due to the extra gearing to reduce the speed and the fact that I would like to add a clutch mechanism of some kind so as not to break any components. Here is some WIP for the front axle: I am looking to make this my best trial truck yet, so all comments are welcome and appreciated! I'm looking at you @Zerobricks, you said there was room for improvement on the Unimog and you could give me some advice on my next MOC , so please feel free to do so!

I just love that Hoonicorn!! So much detail is packed in for a car at that scale. Si mie mi-ar place sa particip data viitoare la eveniment, dacă sunt in Romania, fiindca locuiesc in Canada dar vizitez aproape in fiecare an . Cel putin osa ma inscriu la forumul Rolug!

Thanks! The only mechanical change is I added a stopper on the middle axle so that the drive axle doesn't slip out under any circumstances. Other than that, the only change is to the look of the cabin Update October 3rd The video is completed, here it is!

Thanks a lot!! To answer your questions: The gear ratio coming out of the gearbox is: Low gear: 1:1.4 High gear: 1:3.89 The gear ratio from the gearbox output to the wheel, in the transmission, is 12.58:1, so the final ratios are: Low gear: 8.99:1 High gear: 3.23:1 As for the lack of diffs, I did not find this to be an issue. My steering axle had a sharp steering angle, which allowed the truck to have a good turning radius despite not having diffs to allow the wheels to turn at different speeds in corners. While the turning radius would have been improved slightly with open/lockable diffs, I think it was a good call because it saved weight by eliminating a diff locking mechanism. As well, the combination of planetary hub + defender rims made the pivot very close to the center of the wheel, which reduced the strength needed to steer. Thanks! The only mechanical change is I added a stopper on the middle axle so that the drive axle doesn't slip out under any circumstances. Other than that, the only change is to the look of the cabin

Update September 27 After a busy couple weeks, finally had time to redo the cabin and take some photos. Video to follow soon. More here: https://bricksafe.com/pages/Teo_LEGO_Technic/praga-6x6-trial-truck

Yeah, it was awesome! Hopefully the first of many. Update August 18 The final video is edited and finished, enjoy! Next step is to finish up the Praga truck and made a video with it as well.

Update August 16 This past weekend, Toronto had its inaugural Truck Trial! Thanks to @2GodBDGlory and @lmdesigner42 for participating, here is a photo of the 3 trucks that competed: All the trucks performed well, with different strengths and weaknesses. @2GodBDGlory's Lada was a monster of torque and power, speeding through the course but also destroying a few parts along the way, more info about it can be found here: @lmdesigner42's truck was slow but powerful and its winch really helped it out of some tough situations, but the added weight made some of the gears crunch under high torque as well. As for my truck, I was very satisfied with the performance. The drivetrain never had any breaking gears anywhere, and the only issue is once, under the worst conditions, the drivetrain slipped out of the middle axle, and this is something I will fix by adding some stoppers to limit the range of motion on that axle with respect to the chassis. The gearbox worked like a charm, as expected, as did the suspension. The steering, which I was worried wouldn't be quite strong enough, turned out to have plenty of strength, and the speed of it, and return-to-center provided by the servo was useful. I was also concerned that the lack of differentials could hurt the steering radius, but it turned out to have quite a good steering angle despite its long wheelbase due to its large steering angle, and the fast steering meant it wasn't time-consuming to steer back and forth several times for really tight corners. Overall it is definitely my most capable trial truck to date, and thanks a lot to everyone who helped with advice and feedback along the way, particularly @Zerobricks and @gyenesvi. As a next step, I'm going to redo the bodywork to look nicer, as it was just a temporary build for the truck to be ready for the race, and as I said before I'm going to fix the escaping drivetrain axle as well. As well, a video with the race will follow as soon as I have time to edit the footage. Below are the results of the race: Results Track 1 2GodBDGlory - 1:54 lmdesigner42 - 6:00 Teo - 0:42 Track 2 2GodBDGlory - not completed lmdesigner42 - 8:00 Teo - 0:20 Track 3 2GodBDGlory - 0:17 Teo - 0:19 lmdesigner42 - 5:00 Track 4 2GodBDGlory - 3:19 lmdesigner42 - 12:00 Teo - 2:00 Track 5 2GodBDGlory - 1:45 lmdesigner42 - 5:00 Teo - 1:43

In the end I did something similar to this, yes.

That would be ideal, sadly I don’t have any. I’ll get some perhaps for the next build.

I looked at your Mercedes 6x6 and I see what you mean, you linked the middle axle to the chassis, and the rear axle to the middle. I guess the only issue with this setup is that it does not implement the bogie design, but rather uses regular shocks on both axles, but it would appear to make the design more robust. In the end, this is the design I settled for, with a custom sliding axle design that is robust enough and allows more travel: With the competition only two days away I'm going to rush to make this thing drivable and add some bodywork, and I think I may continue to work on it afterwards to try to fix a few things. In terms of the robustness of the chassis, what techniques do you guys recommend to make it as strong as possible with the fewest parts, to keep weight down? One technique I always use is two have a 2-stud thick build made of beams and 5x7 frames linked together, but in this case, I would like to do things a bit differently as this does not fit above the portion of the chassis where the motors are, where the chassis is only 1 stud thick above and 1 stud thick below.

I know I'm late to the conversation, but I have to say this must be one of my favourite Technic trucks I've ever seen in terms of aesthetics at least. Phenomenal job!!

Yeah, that's a good point, I had thought of that as well but hoped it wouldn't happen lol. Frankly, I'm not too keen to redesign the rear axle suspension after all the effort that went into the current design, but if it must be done I guess I will. My question is how is it possible to keep a constant (or near-constant) distance between both the two axles, as well as from the gearbox to the inner axle?

Update August 2 Back from vacation, I'm resuming work on the truck, and planning to complete it by our scheduled race in 2 weeks' time. An issue I'm facing is on the rear bogie suspension system. While my setup is keeping a fairly constant distance between the two rear axles, and any variation is easily compensated for by the sliding CV joint piece, I'm finding that when the inner axle is lowered fully the sliding CV joint can fall out when the axle slides out too far. One option to fix this is to lower the universal joint coming out of the gearbox, but I don't like this solution as it reduces ground clearance. Another option is to add a set of two 16-tooth gears to raise the existing exit point from the inner axle by 2 studs, which again would allow the driving axle to stay more horizontal and fix the issue, but I'm not a fan of this solution either. Because the effect is so slight, my ideal solution would be to restrict the range of motion of the inner axle slightly to ensure the axle doesn't fall out. It only really falls out because of play at the bottom of the range of the suspension anyway, so this wouldn't reduce the suspension travel by much, rather just brace it better. Does anyone have any recommendations on how to build such a stopping mechanism without being too bulky? How do such suspension mechanisms restrict the range in reality? The following illustrates the issue:

Great, that fits perfectly. Time to order some

Thanks! Yes that could work very well, do you know how deep the hole goes inside that piece, is it 4L? If so I could replace one of the light grey CV joints with that sliding joint and put a 4L axle between them, which would give a whole stud of play to the system, which is more than enough.

Update July 10 It's been some time since the last update, but unfortunately, I was too busy to make any progress. Finally, I made some time this weekend to make some headway, and here it is - a working prototype for the suspension on the rear 2 axles. After several different strategies, I settled on this bogey-style strategy as the best one, mostly because it keeps the distance between the axles closest to constant so that the connecting drive shaft doesn't fall out or get squeezed in, allowing the mechanism to function properly. It is braced very rigidly both longitudinally and transversally, and the high and low mounting points of the links keep it from bending sideways under the torque of the drivetrain, of which there will be lots. The only issue I would like to fix happens when the axles tilt sideways respective of one another. When this happens, the distance between the axles starts to decrease, which applies pressure and friction to the central driving axle, which causes power loss. Currently, this is the only part of the mechanism limiting the side-to-side motion, causing all the more friction. One solution I was playing with was to add torsion bars, but the issue I found was I wasn't able to make the torsion strength soft enough without having ridiculously long arms connection the axle links to the axle under torsion. Any advice on how to fix this problem, as well as any other suggestions, are welcome as always

Good point, I agree that this is usually the case in LEGO. This is a very interesting solution, I like it! As @gyenesvi points out it isn't very robust, and for example wouldn't fare well in a trial truck scenario, but as a proof of concept it's a very creative solution Update May 27 It's been a busy time, so little progress has been made. I'm a bit blocked currently deciding how to properly link and brace the 2 rear live axles, both to each other and to the chassis. The main movements I'm trying to focus on bracing are longitudinally so that the force applied by the axles pushing the car up a slope has minimal play, and transversely so that the axles don't move side-to-side when the truck is climbing sideways over obstacles. Here is a picture of some progress: I like very much @Zerobricks's solution on his Wildcat which allows the rear axles to articulate respective to each other without pressing on any shock absorbers, so that the wheels make maximum contact with the ground, and yet still have shock absorbers used to absorb impact if, for example, all 4 wheels are to be pressed at the same time. To implement this, I plan to replace the grey linkage bars in the image below with this LEGO approximation of a leaf spring suspension: Please post any examples you guys know of where other builders have achieved something similar, I'm trying to get a better understanding of how this should be done. More progress to come soon hopefully!

Glad you're enjoying it! Yes I believe that's what you were saying right @TexasEngineer454 ? Personally that wasn't an option for me on this build because I'm modeling a trial truck that has live axles on all 3 axles. In general my issue with independent suspension in offroad vehicles is that the ground clearance isn't as good as live axles with portal hubs, and the ground clearance under the centre of the axle is reduced when the suspension is pressed, which is not the case with live axles. But it can definitely be made to work, as @Zerobricks did for example on his Wildcat 6x6.

As you say, it holds very well there is no play at all. You're definitely right, using a steering axle with the ball joint end attached to an axle has a lot of play, in the range of a few millimetres even. The way I braced it in this configuration however, it is no longer able to pivot in all 3 planes of motion, but rather only hinge on the axle. It is basically acting as a liftarm at this point, so it would not work for say independent suspension, but it works fine for a live axle where the wheel hub remains in the same plane relative to the steering rack. It doesn't provide a lot of strength if you were to have a force pushing it up, as it can slide off the axle end when you push on it, but this is not a danger in this case because all the force acting on it will be side to side, where it is rigid. I agree, it seems to be an inherent limitation of the part itself. The only way to make a longer steering arm realistically is to use 3x3 half-stud liftarms, which as I said before will knock into the driveshaft, and reduce range of motion. That's not a bad idea, but the issue is that there is still an ~1/2 stuff offset, which the steering link can compensate for, unlike a beam. As well, the narrow midsection of the steering link enables it to still fit when it gets closer to the suspension arm, as the steering hub inscribes an arc at either end of the steering motion.