Do we need hubs?

[BenjaminT]

Concerning the rotors: The wheel would only serve as the rotor "hat." If you've never seen two-piece racing disks, the center "hat" is aluminum to save weight. Using studs pressed into the rotor, you could fasten it from the outside of the wheel and have features in the backing plate to hang it while changing the wheel.

Removing the wheel: I was planning on using 4130 tubing to make a hollow spindle anyways (floating hubs facilitate bolting on electric motors for future drivetrain development.) I could just make it so that it threads into the uprights and leave the bearings alone. If I use a wide enough diameter, it will fit over the shaft of a tire balancer (40mm?) and I could make the centering cones if necessary. The act of changing the actual tire is unaffected.

Disclaimer: I'm only saying it could be done. The vehicle in question will be built from scratch with an emphasis on pushing my design ability. It is definitely less convenient than conventional designs. It probably isn't worth doing but this vehicle is going to serve as my resume some day.

[niky]

Would this mean that tire changes would affect the alignment of the brake discs? Or will there be a simple bolt or clip to hold them in when changing wheels?

[baldlobo]

well most hub designs are double bearing leading to a decent life span for the bearings(two bearings really close would probably lead to one failing pretty quickly; think weight over distance); the hub centric design is so anyone can center the wheel(lowest common denominator); and it probably cuts down on the number of studs needed to carry the cars weight fully loaded(that and you can technically drive a good distance with only missing one lug nut from each of the tires)

[2000mc]

i think i'm looking at it wrong, but i think it looks like its from old 2wd vehicles, spindle, bearings, outer bearing races pressed into the rotor assembly, but they had wheel studs pressed through the rotor.

if you have the rotor attached to the wheel, how do you get the caliper off?

[jamesqf]

Originally Posted by ksa8907

why not perfect electronic braking and eliminate the rotor entirely?

Because the braking effectiveness of electric brakes (regen) depends on the speed with which the rotor rotates. If it's not rotating at all, there's zero braking force - think parking brakes, holding on hills, etc.

[ksa8907]

Originally Posted by jamesqf

Because the braking effectiveness of electric brakes (regen) depends on the speed with which the rotor rotates. If it's not rotating at all, there's zero braking force - think parking brakes, holding on hills, etc.

Right, which is why i said perfect not use the current.

[jamesqf]

Originally Posted by ksa8907

Right, which is why i said perfect not use the current.

You can't "perfect" electromagnet braking to do that, unless you can somehow manage to change the fundmental laws of physics.

[Christ]

Why can't an electromagnet hold stationary? I'm not sure I get why it couldn't be done... Enough magnetism between objects makes them VERY difficult to move. Keep going with that principle, and it could be completely impossible for a human to move them.

Granted, this takes a charged coil, which requires electricity, thus energy expense... but there's no reason mechanical brakes couldn't be MUCH smaller anyway for the final "stop and hold" as necessary if electronic/magnetic braking were used.

[ksa8907]

Originally Posted by jamesqf

You can't "perfect" electromagnet braking to do that, unless you can somehow manage to change the fundmental laws of physics.

you're right, we can't. no sense in trying. i guess ill go back to driving my lifted 4x4, no sense in trying to save fuel. It CAN'T be done.

[niky]

It's a waste of power.

Asking why a magnet can't hold a car stationary against a slope or acceleration is like asking why an electric motor can't do the same. Of course it could, but only by expending power and pushing the car against the force. Far more effective to have a mechanical brake for the last few km/h or mph.