Teo LEGO Technic

I implemented the double rack, and rigidity is indeed improved a little, although most of the play comes from the inherent play of the steering components, and without a longer steering arm it cannot be reduced. As I mentioned earlier unfortunately a longer steering arm doesn't fit in the rims. I did, however, find a solution to the "toe-out" problem - by placing the steering links on 3L axles with flat pin-stops, I managed to bring the link 1/2 stud closer to inline, so that the issue is almost non-existent now. Here's a closer view of the new connection:

You're right, it does indeed cause a slight toe out at the wheels. I will test it out soon in a basic chassis to see if it is an issue, but I'm hopeful it won't be noticeable on a trial truck. Furthermore, I've always found that on LEGO trucks, with steering play, the torque of the wheels pulling the car forward tends to "toe-in" the wheels, so if they start out a bit "toe-out", they may end up actually parallel. Good point, I would have liked longer steering arms. The issue is I want to use the servo motor for compactness, and it only rotates 90 degrees in each other direction. If I were to lengthen the steering arm, that will reduce the turning radius of the truck, which already won't be amazing on a 6x6 with a long wheelbase. These are also great ideas. I tried to use 42099's strategy actually, but unfortunately, the steering axle touches the rims with that configuration when using Defender rims. When I tried using a 2x4 liftarm, it wouldn't fit in the rim in Attika's configuration, and placing it with the long arm inward makes for a really bad Ackerman geometry. I also tried a 3x3 liftarm, but when steering it touches the driveshaft, again limiting the steering angle. One modification I could make to fix the "toe-out" issue is to raise the tow ball position by one stud and move it one stud out to fit. The issue with this is it gets farther from the hub, and the precision is reduced, so I think the better compromise is to have more sturdiness. Do you recommend double racks to improve rigidity/reduce play? Or to stop the gear from skipping on the rack-and-pinion steering? As it is currently built, the steering motor runs out of torque without skipping gears, but I will try using double racks to see if I get more precision. Appreciate the tips as always

I think I solved the rack wobble issue. I added a slider axle as you recommended, and since it is fitted directly underneath the rack, it provides a lot of rigidity. I also added some liftarms on the sides for a bit of extra bracing. Overall, it works excellently

Hey! I can gladly provide more detail, what were you wondering about exactly? Can you give me an example of what you mean by a "slider axle"? Do you mean attaching an axle to the steering rack, which in turn is attached to the axle along sliding pinholes?

Update May 13 It's been a busy few weeks, but it's time for an update. My parts shipped, so I could experiment, beginning with the front axle. I decided to forget about incorporating a diff lock, as it's hardly necessary for a trial truck, and instead to focus on robustness and a good range of motion. I currently have two designs that I'm choosing between. The first one is wider, heavier, and slower, but is more robust, using @Zerobricks' custom portal axle design from the Tiger 6x6, combined with a 24-tooth worm gear attached directly to the steering rack for maximum precision, and driven by an axle-mounted M-motor so that the worm gear limits any play in the system. It looks like this: While this is a good option, my main complaint is that it is quite bulky, the steering is quite slow (and obviously not return-to-center), and I wasn't able to implement a clutch system, so the parts are put under a lot of tension when the steering is fully turned in either direction. Despite the tension, there is no slippage anywhere. Option 2 is my favourite. It uses @Attika's live axle design using the planetary hubs but modified to work with the Defender rims, allowing for a steering pivot that is very close to the center of the tire. I also removed the differential and substituted the steering system with a rack-and-pinion system, plus a servo motor. The main disadvantage of this system is that the steering has more play, but aside from that it practically has all advantages. It is narrower and lighter than the other one, so I could build a truck at a smaller scale with it, which would be nimbler. The steering is fast and return-to-center, and the planetary hubs simplify the transmission, so there is less power lost to friction. The ground clearance is the same in the center and only slightly worse close to the wheels. Overall I love the elegance and efficiency of this design. I attempted to reduce the play by using a longer steering arm, but there wasn't any solution that I could find. While it is possible to extend the hub with 2x4 liftarms when using regular rims, they don't fit in the Defender rims, and using 3x3 liftarms that can protrude enough from the rims doesn't work either, as they touch the driveshaft when steering and severely limit the steering radius. As it is, the steering radius is excellent on both axles. The plan for the rest of the truck is to use a 2-speed gearbox powered by 2 XL motors and install a winch. This will take up all 4 available BuWizz ports - drive, steering, gearbox, and winch. Using the second design, the truck would be significantly smaller, and so the power-to-weight ratio would be better. As for the rear axles, I was looking at using a bogie-style suspension to allow lots of articulation, but in real trucks, they are usually made using leaf springs. Does anyone have any suggestions? I was looking at the 6x6 Wildcat for reference, but it uses independent suspension instead of live axles: https://www.youtube.com/watch?v=cEBgLdNghpQ&t=91s Suggestions are welcome as always!

Oh, I see, that makes sense. I'm used to thinking that the flex point has to remain stationary for independent suspension, and I forgot Attika uses an independent suspension setup repurposed as a live axle.

The only model I've seen Attika make since his Ultimate Pickup is this, and it's only a teaser: https://www.youtube.com/watch?v=BpIwocFrzKI Can you attach the link for the build you're referring to? Do you mean I should brace the red diff in a 7 x 11 frame and drive it with a 28-tooth gear? Just so we're on the same page, longitudinal mounting means perpendicular gears are required: I very much like the idea of having a diff lock only on the front axle, as this makes it easier to create a more robust perpendicular gear system on the rear axles, where most of the torque is going anyway for steep uphill climbing, while also maintaining a good steering radius so the front wheels don't 'drag' when turning with locked diffs. It also simplifies the system by reducing the number of diff locks required. This is an interesting idea, although it would look a little odd with a live axle front suspension and independent rear suspension. At that point might I not be better off just using pendular suspension on the rear, with small turntables to take the friction off the drive axle? I ordered the parts today, including the planetary hubs, new CV joints, 28-tooth double-bevel gears, and 2 more CLAAS tires for a total of 6 (among others). Parts won't arrive until end of the month, so meanwhile I will experiment on Studio.io with different solutions.

Sounds good That will keep the weight down a bit, and save me some cash

That's a clever idea, I like it. It will make it so that it's not possible to incorporate a gearbox, but on the plus side it will make it so that every axle will have more power than just one XL, when it needs it. Do you think 1 BuWizz 2.0 is capable of powering 3 PF XL motors?

How do you mean that I can connect them with locks, do you have an example that uses that? Good point! One issue I have with Attika's design is that the greater ground clearance is achieved using the old CV joints at the differential, which may not take the full torque as well, and also pop out sometimes. As well, the dark grey side only has a 2-stud axle, which works for connecting it to a differential housed in a 5x7 frame, but would not work for a solid axle that I plan to use since I will not have differentials. This makes me wonder if perhaps I should either use your design and sacrifice ground clearance, or I may modify Attika's design to use universal joints (although those are also weaker under high torque). No worries, it's a good point to bear in mind :) Given the new design, I will order some parts today. Progress is going to have to wait until they come, at least in terms of the physical build.

Great progress! That thing is going to be an absolute powerhouse in terms of its power-to-weight, but as others have pointed out, it will be important to brace everything in the transmission as securely as possible to avoid gear slippage with the torque of 4 XL motors. Usually, I make sure, when using XL motors, to have all gears braced on either side immediately with beams. On the other hand, your steering setup with 2 gears on the rack and those massive portal axles looks great! The only disadvantage of the massive clearance may be that it can fall over easier due to a higher center of gravity, but overall it looks like I will be hard pressed to come up with a worthy challenger for our truck trial

That's a great idea! I saw a similar design recently from you, @gyenesvi and noted it down as an idea to try in future: I guess I will be using this technique sooner than I thought . It looks like the new CV joints have a very good range of motion, unlike the older ones, which is more than enough for steering purposes, as well as more robust than U-joints as you pointed out before @Zerobricks. Because this will enable me to make the axle narrower still, I wonder if it isn't a bad idea to scale down the MOC, perhaps choosing a 4x4 model instead? This would enable me to use BuWizz + 2 XL power setup on a lighter build, and so improve the power-to-weight ratio. I could still make the build large enough to use CLAAS tires, perhaps just having them a bit oversized for the chassis, similarly to what you did @HorcikDesigns on your Praga. This also will mean I don't have to invest more money into additional batteries and motors which is a plus . I would probably go with any 4x4 chassis that has front and back live axles, perhaps a Jeep Wrangler or something similar. Why do you think this will happen? It seems to be working fine on Attikas pickup?

I will definitely brace it very well. For your setup, did you have it braced on either side with beams? I'm hoping that will be enough. Just looked up your truck, it's really great looking and performs quite well . Mine will be a bit bigger, not quite to scale with the CLAAS tires, but close. Yes the steering will definitely suffer a bit, I know exactly what you mean by "pushing itself straight." I think I will stick with the regular CV joint, as the stronger ones indeed take up too much space, and I think they can take enough torque for my needs. What solutions would you use to improve the scrub radius? I don't see any reasonable way to bring the steering pivot any closer to the center of the wheel rim. Perhaps there is some solution involving kingpin inclination, but that goes beyond what I currently understand, so if anyone wants to explain a solution I would be interested

Thanks for the info! For a pretty basic setup, the result is fantastic, congrats again!

I think overall the most robust is still the mighty live axle, but that's definitely a good solution for a medium-sized MOC Definitely an option, but do you think they would ship in time? I wasn't able to find sooner shipping times than mid-June. That's an interesting idea. I think overall the benefits of lockable diffs are outweighed by the drawbacks for a heavy trial truck, so I will go with a no-diff setup. By leaving them out you save space, increase robustness, and save weight as there is no need for any mechanism, pneumatic or otherwise, to power the locks. At the slow speeds that this heavy truck will be driving it seems like an unnecessary addition, and as much as it pains me to let them go, it's a necessary sacrifice in the name of performance. I built your custom portal axles from the Tiger 6x6, and their robustness is amazing, I am thoroughly impressed! It will operate even nicer than the Unimog portal axles as the steering pivot is closer to the center when combined with the Defender rims. Since I am eliminating a differential, there is no concern anymore about how to position the locks. In terms of your other suggestions, I will implement them all once I buy the necessary parts, but I had one question. Do the new CV joints enable a large enough angle to be used at the hub for steering? I'm thinking it may be worthwhile sacrificing a bit of strength there to have a better turning radius, and only use the large CV joints at the axle input location, what do you think?

That's a sweet MOC!! I'm especially impressed by the speed it achieved, perhaps I should look into a similar power setup as well, as the physical remote is an improvement in my opinion over a smartphone touchscreen controller. The suspension is also an interesting approach and seemed to work very well, especially once you added the anti-roll bar. I'm excited to see your entry for the truck trial competition .

No, I don't plan to power the axles separately, as I want to hook them all up to a single gearbox. Yes, I will have a working winch. Do you mean it'll be better for climbing sideways on a slope? My concern with independent suspension is that the ground clearance isn't as good, and it's hard to put a lot of torque on it. Sounds good, thanks . Ideally yes, I would like to use the new Daytona bevel gears as they are thicker and could take more torque, but they are priced at $3.50 each on Bricklink, so unless someone knows a cheaper option that's off the table. I will try custom portal axles like you say, probably the ones from your Tiger 6x6, along with the 7x11 frame, and post progress when I'm done. Thanks, and yeah you should start a WIP! As for differential locks, I was also considering eliminating them. Aside from the loss in power in corners, especially at higher speeds, my main question is what perpendicular bevel gear combination can handle the most torque? Is it the 12-tooth and 28-tooth gear? Sounds good! Hope you'll enjoy the process

Massive improvement on the original! My favourite difference is the design of the handlebar area, you eliminated those ugly holes in the original

This model is just gorgeous @Anto! In particular, I love that huge diffuser at the back, and how the rear spoiler moves independently of the rest of the bodywork with the suspension. Did you find that the brick-built panels on the sides of the spoiler fall off easily, or was that not an issue? My biggest question for you is what tools did you use for the video editing, cause it's just stunning The transitions are so crisp, and look like the Hoonigan videos, what video software did you use? The camera movements are also really cool, how did you make those smooth dolly shots and pedestal shots, were they shot handheld or did you use some kind of LEGO contraption? Overall amazing work

Hey everyone! After almost a year and a half of working on it whenever I had time, my model of a Unimog U5000 truck is finally complete. It has the following functions: 4x4 Drive with 2 PF XL motors Steering with PF M motor and linear actuator Remote diff locks, front and back, using pneumatic actuators Remote 2-speed high-torque gearbox BuWizz power More photos on my BrickSafe: https://bricksafe.com/pages/Teo_LEGO_Technic/unimog-trial-truck The whole idea of this model was to build a truck that could both travel at a fairly fast speed as well as work very well offroad, which meant it needed a gearbox. It also meant it needed differential locks so that turns could be taken smoothly at high speed with diffs unlocked, and offroad terrain could be tackled better with diffs locked. The main goal of this model was to create a drive train that wouldn't allow any gear slippage or breaking even under tension in low gear. My solution for this was to use @Sariel's heavy-duty gearbox (http://sariel.pl/2011/02/2-speed-heavy-duty-linear-gearbox/), as well as the new differentials from the 43109 Top Gear car. However even those differentials can't take as much torque as I wanted to put on them, and neither can the universal joints leading to the axles. For this reason, I decided to speed up the transmission before reaching the universal joints and differentials to reduce torque, then slow it back down afterwards between the diffs and the wheels. This would cause a bit of power loss to friction due to the increased number of gears, but it would reduce the torque on the sensitive components and allow me to send more total torque to the wheels. The result is that the 2 powerful XL motors are sped up 5.01 times or 1.8 times (in high and low gear respectively) before reaching the diffs and universal joints, and then slowed down 11.67 times at the wheels. Therefore the final gear ratios in low and high gear are as follows: High gear - 2.33 : 1 Low gear - 6.5 : 1 The result is that the drivetrain is indestructible and never breaks even when run with a BuWizz on ludicrous mode and the wheels come to a standstill. The most complicated part of this build was fitting all of the functionality in the front axle - linear actuator steering placed close to the pivot to increase the range of motion, lots of gear reduction, portal axles, and a differential locking mechanism. Although the result is quite good in my opinion - thanks @Zerobricks for the custom portals - the final construction wasn't as sturdy as I would have liked, and this was the main issue with the final model. The steering has less power than I would have liked with the small actuator, and the custom portal axles bend outwards under pressure when steering over rugged terrain. Overall however I'm quite satisfied with the final result Thanks also to @functionalTechnic for the advice, and to everyone else who contributed to the WIP thread: Enjoy! - Teo

Thanks!

Hey Eurobricks Technic enthusiasts! After being asked recently if I would enter my latest MOC in a race, it occurred to me that it would be pretty cool if we could have trial truck races here in Toronto, Canada as they have in parts of Europe, like Sariel and his crew in Poland. @2GodBDGlory and I are both based around Toronto, and we decided to try to organize possibly the first Toronto-based trial truck MOC race, so we're calling on all builders in the area to see how many people we can bring together! Everybody is welcome, and any information anyone has that could help us out is welcome as well

Thanks for all the positive feedback, everyone! It's nice to see the final result is appreciated after all the work that went into it Thanks guys! Thanks, @Zerobricks! The gearbox worked well I thought, the only issue is you have to come to a complete stop between gear changes to avoid jamming gears. 7 x 11 frames would have probably been a good choice as well for the axles, I just avoided them to keep the size down to make them more realistic. I avoided locking the diff directly because, to ensure the best gear meshing and no slippage, I wanted to place the diffs inside the 5 x 7 frames. Those portal axles from the Tiger look much more robust, if I had come across them before I would have used them. I currently don't own the new CV joints, but if you say they're better I will purchase some. And yes, I would love your help on my next project, your models are awesome! I was thinking for my next project to attempt a pure rock crawler, with the one goal of optimal offroad performance in mind. Thanks, @Milan! I definitely recommend using this gearbox design, I found it worked very well. Unfortunately, I'm not aware of any trial truck races around Toronto where I'm from, although I'm trying to find Technic enthusiasts in my area to compete in races with through ToroLug: http://torolug.ca. If anyone knows of any Toronto-based Technic builders please let me know, it would be awesome to have some trial truck races like you guys have in Poland and other parts of Europe

This build is just astounding! I have no words, I'm simply amazed this thing is actually made from LEGO - I can't believe how seamless the panelling is, and the rear engine bay in particular is a work of art with the yellow and purple complementary colours and golden highlights. This is one of the greats in my opinion

Hey guys! I'm trying something new this fine Wednesday afternoon, my first WIP topic. I always present my models fully built, but this time I'd like to get feedback and advice as I build, to make a better final model, and to learn more from the Eurobricks experts as I go . So please feel free to expound productive criticism, and here we go! For this model, I want to build a 4x4 trial truck that's loosely based on the new Zetros in its diff lock system, but otherwise quite different. The scale is going to be such that it fits with the CLAAS tires, and the main features I want are a combination of a heavy-duty 2-speed gearbox (based on Sariel's: http://sariel.pl/2011/02/2-speed-heavy-duty-linear-gearbox/), combined with diff locks based on the Zetros system, on both front and back axles differentials, with no central diff. This will allow the truck to travel fast in high gear with open diffs and good u-turn capability, and slow and powerfully in the low gear with closed diffs for offroading. To sum up, these are the desired functions: -Precise steering with servo motor -All wheel drive powered by 2 XL's -Two speed heavy duty gearbox -Differential locks on front and rear axles with M-motor -Power by BuWizz -No chance of gear slippage/damage anywhere along the drivetrain, steering, or locking systems For starters, what do you guys think is a good truck to model? Perhaps just a good old Mercedes Unimog? A Russian Ural trial truck?