The human challenge

[Burf2000]

Hey I was looking on youtube and a guy has made a lego vechicle and trailer that can move 65KG which is pretty impressive.

I was wounder before i start it, has anyone made something out of lego that could move a adult male maybe weighing 100kg or something?

I thinking of giving this a go over the weekend, probably be using many many motors, see what free time i get

[Modulex Guy]

Really the main issue you would run into would be traction.

It could be possible to do, you can have a person sit on a dolly, and build one of those house moving systems.

a large vehicle with 40, 50 wheels each driven by a geared down motor for max torque.

[tjavery]

A while back, I built a tractor MOC that could move 43 kg (a very small adult)

http://www.texbrick.com/model_tractor

I think it's quite feasible to build a motorized platform/trailer that could move a lot of weight. It's just a matter of spreading the weight out over multiple wheels and motors.

Edited July 15, 2009 by tjavery

[Burf2000]

Really useful post mate, I am trying to think weather to use power fucntions, v9 motors, or the black v9 ones

Anyone know what the strongest ones are. I am pretty sure they were the XL motor one

[tjavery]

Really useful post mate, I am trying to think weather to use power fucntions, v9 motors, or the black v9 ones

Anyone know what the strongest ones are. I am pretty sure they were the XL motor one

Check out Philo's motor specs and testing page:

http://www.philohome.com/motors/motorcomp.htm

It's hard to compare motor output torque because nearly all of them have internal gear reduction (i.e. output shafts all spin at different RPM's). But, if you look at efficiencies and output torque, the XL motors do look pretty good strength-wise.

[CP5670]

The most powerful motors are the black 5292 RC buggy ones. However, they run at a high speed and building your own, external gear reduction is less efficient than what the motors do internally, so the XL might still provide more torque in practice.

[Burf2000]

I have both if it is the black ones with 2 speed outputs (2 red holes) so i give both a go

[Freddie]

Keep in mind that technic axles can only handle so much torque, before they snap. That, and the XL-motor is known for snapping and breaking things if not used properly.

Otherwise, I'm with Polish Guy on this one. What you'll really need is traction. You can always gear down the faster motors to get torque, but torque is useless if the wheels keep spinning.

[trf199]

Fantastic idea - go for it :). How about seeing how much weight each of your wheels / axles will take comfortably then dividing your weight by the weight each will take. If you have a separate trailer then get the front part to rest on the rear axle of the tractor to get more traction, or sit on the tractor directly.

[Smithy]

I'd also think the issue would be putting the torque through to the wheels. With 4 wheels you'll be trying to pass enough torque through 4 plastic axles.

I'm sure I've seen a Technic model of an SPMT (self propelled model trailer). Multiple wheels, all wheel steering, all wheel drive. Something like this

http://sinohi.blogspot.com/2009/01/scheuer...ted-before.html

I've tried to make my own in the past but Lego don't make parts small enough - the model would end up massive.

[Milan]

If you want to test strenght of the motors, it is better to use just lego vehicle and non-lego cart and tow it with weight on it.

Making lego trailer would require many wheels, preferably without tires, to reduce grip, and surface must be glass or something smooth as that.

Of course transferring all of those torque to the ground on driving vehicle may be the problem (wheels can slip), maybe creating only one vehicle with flatbed and 20 or more small wheels.

[Burf2000]

My worry is breaking axels, i will start the project soon, just trying to make room lol

[trf199]

My worry is breaking axels, i will start the project soon, just trying to make room lol

I'd brace an axle from both ends with a wheel on and put it on some digital scales, then apply downward pressure to it until just before it starts to bend, then you'll have a measurement of how much each will take. Then if you know your weight you'll be able to work out how many wheels and axles you'll need so they don't break.

[Freddie]

Remember you can also reinforce axles using bushes. Some of the torque will pass along the bushes (altough not from one to the other) easing the stress on the axles.

Builders of rally-trucks often use this technique to increase the transferable torque to the wheels while staying within the rules. This is often combined with hub gears, so that the driving axle rotates faster than the wheels, which also reduces stress on the axles.