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Are differentials automatic? That is, do they need a seperate actuating mechanism, or do they detect turns mechanically and internally?

a differential contains all the parts it needs togther. No actuating extras are required.

I kinda like them actually, because they are semi "intelligent" yet only require a housing and three gears. Genius design.

Brilliant, that'll simplify the my Go-Kart idea.
Say I got a differential from a very small rear-wheel-drive, how much would it weigh?

You will kill the fun of driving a go-kart if you add a differential to it!
A go-kart must skid to go around a bend because it has no differential...

Then you will need a suspension. If you don't have it, a wheel is likely to loose contact with the ground in sharp bends. The differential has the bad habit of sending all power to the wheel needing less torque , so you will be powerless in the middle of a bend...
Normal cars have suspensions keeping the wheels in contact with the ground.Sports cars go further and have self blocking differentials. 4Wd use manual blockers. And true Hummers (military version) have some kind of all-mechanical "smart" differentials.

Oooh, so Go-Karts *don't* need a differential?

And if they don't have have differentials, then they don't need suspensions?

Oh yeah, I didn't really describe the plan. My brother is in on this too, hopefully we'll actually build it come summer.

So:
Wooden frame and construction, obviously with a bit of metal (bearings, screws, etc.).
Three wheels, two rear driven ones and a single, sturdy and thick front wheel, used for steering.
Mid-mounted standard Go-Kart (3 or 4 HP) engine, with small Go-Kart clutch, and then leading to a small motorcycle transmission.
Motorcyle-style straddle seat, with left foot leading to clutch pedal, right foot to gas pedal, gear shifter to the left, handlebars with bicycle-style brakes on each one, leading by cable to rear wheels.
There should be a passenger seat as well. So maximum load on the vehicle could be aimed at 250 pounds.

Quote:Oooh, so Go-Karts *don't* need a differential?

technically, no. But it does depend on what kind of gocart you are making. A racing one may not have a differential because it is designed to go round sharp corners, and then sliding action of the skidding wheel helps that, and also the heeling action of the car will tilt one of the wheel off the ground like antoni said, cutting the power to the wheel which is on the ground.

But that said, a differential is much kinder to the setup, and will reduce a lot of wear to the mechanical parts.

If I really don't need a differential, I don't think I'll use one. There would be three problems that I can foresee:
a) linking the transmission output shaft to the unit, while maintaining good seals and all that. I'm trying to avoid soldering or welding.
b) expense - a rebuilt differential from a compact car maybe 20 years old is surely going to be priced in the hundreds.
c) weight: differentials are heavy-duty like transmissions, so I guess a small one could weigh up to 50 pounds, and that ain't a picnic to mount on wood. It'd weigh more than the transmission and engine together! :-?

But if I'll have to make the vehicle axles and chassis that much stronger and flexible without a differential, I'll use one.
Although if I need to set up a suspension system with a differential, I'll avoid differentials at all costs!

The trike you describe will be more stable if you reverse it: Two front wheels and a single rear wheel...

In the UK people enjoy small sports cars designed like this. That's more stable than a single wheel in the front.

Not so small jet powered speed record cars are like this also..
http://www.thrustssc.com/thrustssc/Engin...rster.html

Really? So one driven wheel in the back, eh? Maybe that could work, but then I'd have to complicate steering. Although it would make the whole differential issue disappear.

What do Go-Karts use for a steering sytem? Parallelogram, Rack and Pinion...? I'm assuming there's no power steering involved.

I probably missed a bunch of stuff, but...

You have a top-mount engine, right?


Well, If you just rotate the axle...



See what I mean?

It would be nice to have some way to slow down, or even stop, besides killing the engine though. I've never ever seen one made that way, but it should work! :lol: