Hi Bill, You have nailed it. Unsprung weight takes all the fun out of a car. There is a place for hub motors - with a gear box. The OT ELF I use is all unsprung (unless you call fat bike tires suspension, then the hub motor IS spring weight). It weighs about 150lb with batteries for a decent commute, lunch, laptop, and a change of clothes, and it is slow at about 27mph in warm weather. It gives a nice balance of cargo carrying ability, weather protections, and moderate aerobic exercise. It is a good combination if you don' t want a car, but want to replace one - up to a point. If a person needs less distance capability than I, the ELF is even better, though the payback falls off.
An odd and silly idea just flitted through my mind - maybe if you accept minimal compliance you can suspend a hub motor.... Bent Mike On Tue, Dec 24, 2013 at 4:38 PM, Bill Dube <[email protected]> wrote: > The supposed space savings is very much in the mind of the executive that > funds a hub wheel endeavor. It turns out not to really save much space, > unfortunately. > > The gear losses are about 7%, give or take, when you use a gear reduction > to centrally mount a small high-speed electric motor. When you use a gear > box, the motor/gearbox combination becomes much smaller and cheaper than > the direct drive hub motor. This is because the torque of the motor is > directly proportional to the size and the cost. Speed (rpm) has little > influence on the cost of a motor. A gearbox thus greatly reduces the cost > and makes the motor/gearbox combination smaller, so there really, in the > end, is not much space saving. > > The trouble is, one cannot completely solve all of the innate problems of > an in-wheel motor in a highway capable vehicle. At least not economically > for most of the problems and for the other problems perhaps not at all. > This is what every major car manufacturer has independently confirmed. > > The very first attempt was by Porshe in the late 1800's. > http://press.porsche.com/news/release.php?id=642 > It was not really highway capable, however, as its top speed was 22 mph. > > I could go on and on. (I have done so before. Look it up in the archives.) > Hub motor vehicle prototypes die the "death of a thousand cuts". It is not > just one problem, but many subtile, very serious, issues. Each takes its > toll to eventually kill the production vehicle. > > I should note that for low speed vehicles and for racing vehicles, hub > motors and individual wheel motors can sometimes make a lot of sense. Often > for these specific applications, the problems fade away and the advantages > can win out. > > Bill D. > > -- Put this question to yourself: should I use everyone else to attain happiness, or should I help others gain happiness? *Dalai Lama * Tell me what it is you plan to do With your one wild and precious life? Mary Oliver, "The summer day." To invent, you need a good imagination and a pile of junk. Thomas A. Edison<http://www.brainyquote.com/quotes/quotes/t/thomasaed125362.html> A public-opinion poll is no substitute for thought. *Warren Buffet* Michael E. Ross (919) 550-2430 Land (919) 576-0824 <https://www.google.com/voice/b/0?pli=1#phones> Google Phone (919) 631-1451 Cell (919) 513-0418 Desk [email protected] <[email protected]> -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20131225/d8e3d386/attachment.htm> _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
