marshmallow

Hi @ludovisser, thank you for sending this. I don't know how I missed it the first time, as I had spent a lot of time researching solutions here. So I actually ended up finally building that chassis last week using the Lego Technic Embodiment's design as a base, added the new differentials to improve gearing down, and it's worked reasonably well, carrying a lot of weight on 4 axles (it's a logging truck), except for the drawback of the frame height being too high. I'm still working on improving the front steering axle and steering geometry. I liked your design, I think it could maybe even work well with the new 5:1 wheel hubs with some modifications. I'm concerned about that crankshaft part as someone else mentioned, in particular when the axle is going over an obstacle on one side only and it twists a little as the suspension is activated. I also can't fully visualize from the Stud.Io file where the driveline will flex as the suspension goes up and down, it would probably be easier to build it in real life to see. Have you built a truck using it already, how did it behave?

Hi everyone, I am planning a tri-drive logging truck, 18 or 19 studs total width with tires. Front steered axle plus three rear powered non-steered axles. Does anyone have a good design for powered suspended rear axles that can be installed in such a tri-drive configuration? Most designs I have found seem to be limited to two powered rear axles as they are either: - On a tandem bogie, so either way you connect power (through first axle or from over each axle) prevents you from connecting a third axle. - With two transmission lines that drop down to the first and then second axle independently. Either laid horizontally side by side (i.e. Ingmar's truck T2) or vertically on top of each other (i.e. D3K's 6x6 truck). A third line wouldn't fit horizontally, and if you try to put it vertically, then the angle for the U-joint for the third axle would be too aggressive. The only design I've found so far that may work is this one from Lego Technic Embodiment and I am planning to build it and test it. I'd appreciate any comments on it. This is an interesting construction, I am just afraid the 16-tooth gears may slip under heavy load as the suspension moves up and down changing the angle between the 16-tooth gears. It also requires more headspace above each axle for the mechanics, so I would need to get creative to maintain a realistic frame height. Would appreciate any guidance from someone who has sorted this out previously.

Hi Sariel, thank you for posting. Do you think this design would have less resistance/friction in the transmission compared to a subtractor? Specifically by not having all movement go through those three small 12-tooth bevel gears inside the differentials. I'm wondering as that could maybe allow me to use less gear reduction and have the tank run faster.

Hi @CharlesD, Those tanks/ripsaws look awesome! So I had this same problem with a tracked vehicle with subtractor and did a lot of troubleshooting. Same issue of power cutoff after 30s. Initially, I thought it was an issue with one of the BuWizz units or motors. It wasn't, the transmission was just not geared down enough. The easiest solution is to gear down further, I'd suggest 3:1 with the 24 and 8-teeth gears. I did that close to the axles that drive the sprocket wheels, it was a simple fix and solved the problem for me.