Quote:
Originally Posted by serialk11r
I don't consider replacing the brake simplicity, because that involves making a rather specific hub motor for every car. Besides, reduced braking function on the rear wheels is quite a large compromise, that I think sensible people would consider unacceptable. Weight transfer may leave the rear axle with perhaps under 40% of the weight for taller vehicles, but the hub motor is never going to be able to apply enough torque to lock the wheels even in that case. Losing even 20% of braking capacity is huge. And on RWD cars (I know I know, most people here think RWD is stupid or something), you absolutely cannot replace the brake because the front does more braking.
Many cars aren't coming with drum brakes anyhow, because they suck. The secondary drum brakes used for the handbrake are not going to suffice either. Heck, the Honda Accord (current one at least) has rear disk brakes.
Even if braking performance weren't an issue, is embedding the motor armature into a new "brake" hub really easier than just bolting a motor to the spindle and using gears?
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Could easily insert the permanent magnets into the slots of a double-wall disk brake, and use the existing caliper mounting to support the fixed electromagnet assy. Braking loads being greater than acceleration loads, these structures are already more than adequate strength.
Still better to put the permanent magnets
on the wheel itself, with the electromagnets fixed to the strut with a ring bracket. Bolting on a motor at the spindle is needlessly heavy, and applies the torque at the worst possible location--the hub.
Dump the entire stock drivetrain, fuel, muffler, radiator, etc. and go to 4 wheel electric drive, electronically controlled. Maybe have onboard aux power unit in form of a lightweight diesel generator to keep the batteries topped off and have regenerative braking, reducing the number and weight of batteries needed. Having saved the weight of the combined conventional driveline/fuel/transmission, etc., the car is now much lighter, some of which weight is replaced by the new batteries, etc..
If overall final weight is reduced, brakes can be reduced accordingly since now they bear a smaller load. Also the car structure itself, which now carrying a lighter load, needs less strength and attendant weight to be sufficient.