GAZ 3351 articulated tracked vehicle

[Sariel]

Ever since I've started to use beams-built tracks, I have been suggested to use rubber axle joiners instead repeatedly. These are a bit expensive when you need a few hundred of them, but I've finally hit a clearance sale, and well, here's an experimental vehicle. It has a number of problems, but now at least I know what not to do when using rubber tracks:

Reading & photos: http://sariel.pl/2017/05/gaz-3351/

[Milan]

These tracks look cool and have great traction, but they indeed have some issues, like those you described. Driving them with rubber tire or rim probably was my problem with them, too. It can be somewhat solved by driving all four (or eight) "sprockets" and give them at least double the traction. Other solution is to use the sprocket that will engage with axles on the tracks directly, like using old big Lego gears.

Nevertheless, I too got a great deal for them (1000x) and had a great fun with those! Still experimenting with custom brick built sprockets.

[MajklSpajkl]

I also couldn't resist 1k in our LUGs bulk buy a few years ago. I wanted to try out the wheel designs by Milan and I have a similar tracked vehicle waiting to be presented.

@Sariel: Another great built as to be expected from you :-) Do small LAs only articulate the vehicle, or can they pull the front up and down as well? I used big LAs, which articulate and pull up and down. The only problem is, that the joint looks to big and unnatural. I managed to camouflage it a bit. My tracks are now almost one year on the vehicle and it seems as they stretched a bit, since the grip is not as good as in the beginning. They are driven by all 4 sprockets per cart.

[Sariel]

The LAs articulate left/right only. I've trial up/down articulation in a Vityaz DT-10 model a few years ago, but there was a lot of backlash due to weight and length of the model. So this model has "free" up/down articulation, which, by the way, makes it hellishly difficult to pick up and carry around.

[Milan]

1 hour ago, MajklSpajkl said:

My tracks are now almost one year on the vehicle and it seems as they stretched a bit,

True. Forgot to say about it. I made that "mistake" by letting them sit on a wheel and they stretched a bit. Luckily it was a very small wheel and it has low number of rubber connectors.

So, it is best to remove them from a model if any stretching is involved.

[Leonardo da Bricki]

Another great model!  I have wondered about making tracks like this and experimenting with them, but now I know what I should and should not do. Many thanks, Sariel!

[JonathanM]

Very cool. I'm going to be on the lookout for cheap rubber connectors in bulk :)

I'm sure you've thought of using axles with stops (alternating from each side?) to help with the rubber slipping off thing (or maybe even half bushes on 6M axles?), but I guess they're not cheap either when you'd need a whole heap :)

[Tommy Styrvoky]

Interesting model, regarding the steering issues with the LA's, it may have helped  a little if you used differentials instead of a solid axle between the sprockets. Also I have been looking into designing sprockets for the custom tracks, and it is rather difficult to do a conventional teeth outwards based sprocket. I think it would be possible to do something similar to what the T-34 uses, having the track guide horns acting on bars mounted inside of the sprocket. 

Maybe something like this would work, It protrudes a little beyond the wheel, though I think it would work.

Edited May 29, 2017 by Tommy Styrvoky

[Sariel]

I'd hate to use differentials, I'm pretty sure this would lead to slip situations while handling obstacles, just like in the cars. As for the sprocket wheel, the problem isn't making something protrude beyond the wheel but making it protrude at spacings that fit between the track's teeth perfectly. It's pretty tricky, but one possible solution is using one of the old gear wheels to fit with axles in the track:

[1gor]

Very impressive, small and beautiful 

Great idea with rubber tracks

[AFOLegofan66]

your vehicle looks great and appears to work well. I have tried the same tread and was not to happy with the overall performance. I am using the new plastic track with the new rubber grommets.Lego 24375, Works like a charm!!