Teo LEGO Technic

What a gorgeous truck!!

Hey guys, I know it's been some time since the last update, but I've finally had time to put some more work in. The chassis is pretty much completed, I only need to purchase a small pneumatic actuator to finish setting up the front diff lock, but everything is ready to install. I completed the following: Added Panhard rods front and rear to centre axles Modified the position and connections for the suspension to enable smoother travel Installed and secured the battery box and pump with @functionalTechnic's auto-valve assembly I'm really really pleased with the overall performance of the truck. It gets good speed in the high gear and soooo much torque in low gear, with no risk of gear damage due to the clever transmission setup. The diff locks work like a charm, and the steering has plenty of angle as well as plenty of strength despite using a small actuator. My only complaint is that the front portal axles aren't nearly as sturdy as the rear ones, but that's the sacrifice for compactness that I have to make by using @Zerobricks custom portal axles, and they still hold together well enough to function properly (I just would like to see them strong and unbreakable for my own satisfaction). Here are some pics of the chassis: Let me know if you guys want to see a video of the chassis overcoming some obstacles, or if it can wait until the body is finished for a full video. Now it's time to start work on the cabin. I've decided to go with the U5000 look, I love that simple boxy offroad look. Any suggestions for where I can find more pics of that model? Hope you guys like it Let me know any tips for improvement!!

Good point, that’s my hope as well. I’m glad I went to the trouble of changing the driveshaft, it’s a substantial improvement

UPDATE: The main fixes are: Lowered the drivetrain in the chassis to reduce negative caster, and increase space availability (great tip @gyenesvi ) Used the extra space to change the mounting of the M-motor that controls the gearbox to be in the center of the chassis, above the rear axle Another improvement was moving the diagonal beams inward to allow the suspension to attach closer to the body without hitting the chassis, and so make the side-to-side component of the suspension softer for better offroading: Do you guys see any opportunity for improvements? How high should I make the truck rest - higher is better for clearance, but lower is better for toppling over. I will probably stick with the original Unimog design: Done, good catch! Please let me know whatever tips you guys have for improvements! I really want to nail this project, it's coming along really nice

While I'm working on rebuilding the chassis to lower the drivetrain, I also decided to redesign the gearbox. Now the actuator is centred, and this keeps the sliding motor section from getting angled by the previous off-center actuator - this means less friction, and so less power lost:

This is a really cool MOC! I'm excited about the next progress report .

Ohh ok got it. I’ll redesign the chassis then, wish me luck!

Oh ok, that makes sense . What would that improve, the negative camber angle? Because the steering is equally solid with or without the camber angle it seems. It would be a pretty major redesign I wonder if it's worth the trouble... That's a good idea . At the rear, the challenge is that the pneumatic pump gets in the way but I will try to get around it. The other issue on the rear has been that I can't move the diagonal beams any further inward as they will touch the axle, so the suspensions have to be mounted further out than I would like, stiffening the side-to-side movement of the suspension. I will be mounting the suspension closer together on the front however so that the front axle has more side-to-side movement. This is consistent with the LEGO Unimog, and I think it's useful for keeping the vehicle more stable - the heavier front of the car can tip over more easily.

You're right, definitely would be nice to see some better steerable portal axle options from LEGO The entire drivetrain is indeed, as you say, quite high in the build. The reason for this is that, when building the front axle, the only solution I could find to build the front axle to be steered by a linear actuator, powered, and have a pneumatic differential lock system, involved building it with the large ground clearance. After that, I built the rear axle similarly as there was no point in modifying it. Next, I placed the motors lower than the drivetrain in order to reduce the extra ground clearance, which does not match the clearance in a real Unimog, and the extra height would have made the truck fall over easier when climbing over obstacles. Do you think there is a solution for keeping the drivetrain flat, but also avoiding excessive ground clearance? It would require a rebuild of the chassis so far, and although it would reduce the negative camber, the steered axle was causing issues in testing even when placed flat, so I don't know if much would be gained The issue with the rod is the tight space I have to work with. After lots of different iterations, here is the best I could come up with. I just need to brace the shock absorbers better:

Thanks man! Yes, it is getting very large In terms of ground clearance, the photo shows how the suspension will look when it is fully compressed - normally it will be much higher: On the front axle, I didn't mean negative caster I meant camber. As you say, there is no way to get rid of the negative caster - that's part and parcel of the ball joint mount - the issue is that the wheels tilt and sag outwards as the car drives when steering. I can post a photo to show what I mean: I don't think there's much I can do to fix it - implementing Ackerman geometry is too painful, and either way the custom portal hubs aren't as robust as the LEGO ones. On another note I could use some advice - how do you guys think I should mount the axles? My initial plan was to use Panhard rods, but even with the long linkage (below), there is quite a bit of side-to-side movement due to the long suspension travel, and the fact that Panhard rods naturally inscribe an arc. Should I use a different centring method? Like in the 9398 Rock Crawler?

Hey guys, it's been a long time since I had time to work on this project, I was just too busy with school. But with the semester over, it's finally time for an update: The gearbox is installed in the chasses and the beginnings of the chassis are started, complete with strong bracing and diagonal beams. The M-motor for actuating the gearbox is installed, as well as the M-motor that drives the pneumatic pump and auto-valve (based on @functionalTechnic's design here). The job now is to install the suspension mounts to the chassis, and to position the Panhard rods that center the axles. An issue I've found is that the wheels on the front axle start to develop an unwanted negative camber angle when the car drives with the steering all the way to one side. This may be because the tires on the front aren't braced as strongly as on the rear (due to the custom-made portal axles), or maybe it is due to the lack of Ackerman steering geometry (the wheels pivot equally when steering). It's not a very serious issue, but I would like to be able to resolve it. Otherwise, a preliminary test worked like a charm. The truck gains pretty decent speed on high gear, and has a ton of torque on low gear, without any gear slippage happening or other issues. It's just so great to have time to work on this project again after so much time!

What an amazing build! I can't believe how many functions are packed into that tiny scale!

UPDATE: Finished bracing the front axle: Built the rear axle, similarly to the front but much sturdier since it doesn't have to be steered: And here's the beginning of the gearbox. Design uses Sariel's principle (http://sariel.pl/2011/02/2-speed-heavy-duty-linear-gearbox/) but with 2 XL's. Final gear ratios from the gearbox outputs are: 1. 1:5.00 2. 1:1.80 This ensure that even in the slow gear, only the torque of 1.11 XL motors is driving the front and rear diffs, and so no gear damage will occur. The slowing down at the wheels will be: 1. 2.33: 1 2. 6.48:1 This gives it more than enough torque on the low gear, and quite good speed in high gear. Thoughts? :)))

Hey guys, sorry for the long break I took from this MOC, but school has been very busy. Silly real life priorities kept me busy But back at it! My choice right now is about what wheel-base to use: normal or long. The image below shows both: I have to figure out how to fit in the heavy-duty gearbox as well. My thoughts are that the long base gives me more room and more climbing ability, but the added weight may reduce performance, and the small actuator used for steering may start to run out of power. The smaller base will be lighter, but requires a more compact design, and also won't climb as steep slopes. Thoughts? Let me know guys, I'm going to get back to building now I have more free time!

Thanks! Bouncy was what I was going for :)) Fair enough, I was going for something like these: I used RM8's setup from his Sunset Baja Truck. Unfortunately, your're right, at this scale the buggy motor has to take up cabin space. That's a good point, I didn't try removing the diff. It probably would slow it down a bit cornering on smooth surfaces, but offroad would probably help. I'll try that next time