After way too long, I have decided to actually try to finalize something I have built. I decided to go with something nobody has ever done before with Lego, and this is what I have so far:

<snip>

Sorry, no pics in the OP, as to not scare people away with my horrendous start of my WIP...

Anyway, it's a zero steer crawler. You can scroll down to post #4 to see the pics of the actual WIP as of now.

The design uses four driveshafts for four functions: left wheel drive, right wheel drive, left wheel steering, and right wheel steering. In the middle, there will be a gearbox controlling the direction of the two steering outputs, with an M-motor to steer and a micromotor to shift the transmission rings. The design will be based off of Effe's direction reversing gearbox, but with fewer outputs.

The whole vehicle will use 4 IR channels, two of which are occupied by the steering motor and gearbox-shifting motor. The other two will be used for the two driveshafts, one XL motor per channel per driveshaft, with a mechanism on the remote to switch from normal to skid steer drive.

Of course, comments, criticism, etc. is greatly appreciated!

Edited December 15, 201311 yr by TwentyLeggedHen

I can't figure how the normal steering works? Will have to see it in action. Skid steer is pretty cool and unique to a crawler don't think i've seen it before, i think it would work good with baloon tyres.

It's pushrod steering for each wheel, I just haven't built the other side. When it is in zero steer mode, both driveshafts spin the same direction; when it's in normal steer mode, the driveshafts for left and right wheels spin opposite directions.

Finally, some progress...!

Sorry I posted a topic about a piece of garbage. I have finally updated the axle, and it looks and works much better now. And to wonder why I only got one reply about this pile of megablocks, and it was probably just to be nice even though it was terrible!

Looking back at it, it really looks sickening

This is my first attempt at really building anything studless, and I think my efforts to start building with studless parts paid off.

Here is a pic, and I apologize for the noisy background, I couldn't find a better place to shoot it.

The steering is now stronger, as I have replaced the links with LA's, and the drivetrain has much less friction now.

The planetary gear reduction:

Four driveshafts, for 4 independent functions:

A nice close-up shot, showing the mounts for the links that will soon be placed once I build the gearbox:

And the portal axles, inspired by efferman:

Three positions of the steering:

Straight:

Normal steer:

And finally, the main function of this crawler, zero steer.

So now that there's an actual project in this topic, what do you guys think?

And as always, C&C greatly appreciated!

Looks very complex!

Yeah, I've already used up all of my 16 tooth gears as well as 12 tooth bevel gears. I'm working on the central gearbox right now and already I've had to take some of the 16t gears from the planetary gear reduction assembly.

Looking good! Keep at it, going well for your first studless. :)

While I like your dedication, I would suggest you to start simple for the first time... I also made some very complex offroaders at first, which just didnt work good...until I decided to KISS

I'm not sure if you know already but the planetary assembly won't work as it is.

Currently it only drives the inner teeth on a gear, a planetary reduction needs the outer ring to be stabile.

Frankly, a simple portal axle would propably work better.

That said, you really know how to cram a lot of gears into a small space

I'll defo be keeping an eye on this topic.

Looking good! Keep at it, going well for your first studless. :)

Thanks man! I'm starting to like studless a bit more now.

While I like your dedication, I would suggest you to start simple for the first time... I also made some very complex offroaders at first, which just didnt work good...until I decided to KISS

Well, I think I'll just try to finish this project first and see how it turns out. Then maybe I'll build something much more simple. :)

I'm not sure if you know already but the planetary assembly won't work as it is.

Currently it only drives the inner teeth on a gear, a planetary reduction needs the outer ring to be stabile.

Frankly, a simple portal axle would propably work better.

That said, you really know how to cram a lot of gears into a small space

Oh, sorry. I forgot to say that I'm using these wheels on it which give it a 3:1 planetary gear reduction ratio:

BTW, there are 31 gears on the axle alone

Edited December 15, 201311 yr by TwentyLeggedHen

Here is what yours does

How I thought planetary reduction works

Am I wrong?

Edited December 15, 201311 yr by skppo

Oh, I guess you're right. But it's something very similar, I got them mixed up.

Here is what yours does

How I thought planetary reduction works

Am I wrong?

If it was set up that way, the wheel wouldn't turn, since the outer gear is the wheel rim.

Oh, I guess you're right. But it's something very similar, I got them mixed up.

I think they are the same. The part that is fixed is just different than a normal planetary gear.

And the portal axles, inspired by efferman:

And as always, C&C greatly appreciated!

i think under load the bevelgears will jump over, because the connection is not stable enough

Ok, I'll try to fix that! But I don't want to make the ground clearance any lower, and it seems like I would need reinforcement on the top and bottom. :/ Well, I guess I'll try anyways.

Oh wait, I see a solution. Will do that later.

is this an option for you?

100_0565 von efferman auf Flickr

I guess. But I think I'll have to change the mounting points. I want as few u-joints as I can though, as the drive will transmitted through a total of 8 u-joints, and 12 if I used that. I will definitely consider it though!

I'd give up the extra reduction at the kingpin before the planetary gear hub, and simply use the system with a gear that's usually used with linear actuators. The drive-train would be simpler and the kingpin wouldn't have to transmit rotation. I can imagine your current setup would stall the king pin under the weight of the vehicle.

I hope I was clear...

Edited December 15, 201311 yr by Lipko

I thought of that, and it is a good option, besides two things - ground clearance as well as gear reduction as you have already stated. The vehicle has poor ground clearance with the current setup and even less with that.

Why don't you just drive the uppermost gear that's in connection with the wheel hub? And ditch the other wheels inside the hub...

Or just add an extra 12T double bevel gear on the right and push the hub outer with half stud.

Edited December 15, 201311 yr by Lipko

I have used all five gears in the hub because without them, there is a lot of bump steer due to the pinhole in the center of the wheel as opposed to an axle hole. I'm not sure I get exactly what you're saying, where should I be putting the 12t gear?

Above the 20T wheel that's connected to the sun gear. But maybe that's stupid, because you couldn't properly attach the wheel hub to the king pin.

Ok, I get what you're saying now. I think I will try it as is first, and if it doesn't work, I will modify it

Oh, and by as is I mean with some modifications I'll make soon to make it stronger.

Edited December 15, 201311 yr by TwentyLeggedHen