Hi

I am making an extreme off roader, the idea is to use a triangular frame connected at the ends by 3x3 T lift arms and connected in the middle by pulleys or a wheel with the right hole arrangement, or this, the triangle frame has a wheel on each point, hopefully Ill get some third party tires when its almost finished

however I am not sure how to drive the wheels, now I could use motors connected to 1 wheel for each side as you can just rotate it if you want the driving/driven wheel on the ground but the motor might just spin itself silly instead of spinning the wheel, as in-wheel motors don't connect to the chassis

I think gears are a bit odd for this and might get caught on the driving surface, maybe pulleys could work or chains but I'm not sure if its strong enough or the right size. he gears had loads of play in them when I tried with them, it was like they were in a lift arm with holes that were too big!

Also the problem with gears is the axle in the middle spins relative to the frame because of the pulleys, this is good as it can rotate the wheels by connecting that axle to a strong motor and hooking that up to the IR receiver.

it would have been a little better to have each three wheels spinning but it adds weight and if you did it would change the direction the car moves in if the frame for the wheels rotated.

When the whole frame rotates it acts like one big wheel , might be a bit bumpy but still.

Edited January 15, 201411 yr by SNIPE

I would try a chain solution maybe a chain that encircles all three wheels. At one point I would pull it inwards with the driving gear.

When I first looked at the picture I had this in mind:

http://www.wagner-haltern.de/shop/db_images/gallery/detail/26f5bd4aa64fdadf96152ca6e6408068.jpg

;-)

Edited January 15, 201411 yr by TinkerBrick

How about just gears, like on a tandem axle? I think zblj used that on something of his.

XL motor on each wheel, XL motor in the middle, 3 XL motors spinning everything.

XL motor on each wheel, XL motor in the middle, 3 XL motors spinning everything.

Unfortunately, however awesome that idea may be, I don't think it will work; you would need an electrical slip ring that doesn't exist yet in LEGO.

TLH

How about just gears, like on a tandem axle? I think zblj used that on something of his.

Like this?

Forget my XL madness, just a quick question, is it designed to climb stairs?

Like this?

Precisely.

Personally, I would love to see 4 XL motors per wheel thingy- that's 16 XL motors! That would be an EXTREME off-roader.

TLH

My stairs are too high slightly, it could go down them fine but I want it to go over other stuff too (indoors)

I think the torque will be too much for gears but I only got some 24 tooth gears and secured them 'lightly' so ill try again soon.

Edited January 16, 201411 yr by SNIPE

Unfortunately, however awesome that idea may be, I don't think it will work; you would need an electrical slip ring that doesn't exist yet in LEGO.

TLH

Just mount the battery box on the assembly as well

Like this?

Looks like the TriStar wheels from an 'old' movie. There are few variations on such design. Google 'Lego Tristar Wheel'. My favorit design is the one that uses the Y 1/2 width liftarms from gigamesh... I've been collecting those and have enough to build a tristar vehicle ... but who got time for this?

I have built a super duper version of this type of wheel. I will try to post pictures later tonight.

take a look

I have also built a tri-star wheeled vehicle several times the last using power function motors rather then a NXT brick that I used the first time.

http://hiddenforest.co.nz/personal/lego/legoa.htm#tristar

I have mocked up an idea for a Tri star bogie that uses large wheels. Man, it's a royal pain in the big behind to make these things.

It's pretty strong, but uses an obnoxious amount of parts, and is really big.