Quote:
Originally Posted by thingstodo
Last time I looked into it (as deeply as a non-mechanical guy like me can) the issue was having the 'car' hanging off one side of the wheel, not both sides.
The hub motors on scooters, motorcycles, bicycles have the advantage of bearings on both sides of the wheel, connected to support arms on both sides of the wheels. So when the bearing surface wears a bit, the wheel is still level, the clearances still work, etc
On the car wheel, once the bearing(or bearings) start to wear .. just a little bit ... less than when the mechanical guys start to worry about it ... the tight tolerances on the rotor (rotating part) and stator (stationary part) of teh wheel motor ... get tighter. When there is enough wear to let the rotor rub the stator, metal shards come off, plug off the gap between rotor and stator ... and the motor comes to an ABRUPT halt. The wheel LOCKS in place and SKIDS the rubber off.
This sort of catastrophic failure was seen ... rumor only ... since NO ONE in industry wants to talk about things that they try that FAIL ... starting before the first set of tires was worn off to about midway on the second set of tires. 20,000 miles to 60,000 miles.
I have yet to read about a fix for this. If someone does figure it out, it will likely be patented ... so perhaps there are several companies with a magic solution already. But I have seen no evidence so far.
On this topic ... is there a technical reason why car tires and suspension don't use support (and bearings) on both sides of the wheel? Or is it just that it makes the car look goofy?
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There is no advantage to supporting the hub on both sides than just one. The hub just has to be sized for the type of stress it will be under. For an example, the length of the axle stub and therefore distance between the bearings could be made much longer than the width of the wheel if need be without the need for supporting it on both sides. The axle stub will need to be made a beefier if it's supported on only one side. But the weight penalty of the bigger axle stub would likely be not much different than the linkage to the other side.
If supporting wheel hubs on only one side with heavy wheels were a problem there would be a lot of big commercial vehicles with worn out wheel bearings.
The problem mentioned above may be from off centered bearings. But that is possible to solve even if supported from just one side.