Peri, I am wondering if not having a differential but driving each wheel independently with an electric motor does not create the issue that one would expect. If you have a solid axle car, and turn a corner, one or both wheels will scrub the road and the car will try to drive straight forward. The Tropica electric car, also called the Zebra, the four wheeled fiberglass sports car looking one, not the three wheeled enclosed Zebra, had an Advanced DC 7" motor at each rear wheel. A belt drive was used to transfer power from the motor to the wheel. The suspension was independent at each corner. They did have two Curtis 400 amp controllers, I am not sure if they were tied to the same throttle input, or if there was some linking of the controllers. I know some of the more modern Curtis controllers can be linked to the same model of controller to power a vehicle with one throttle and two motors. The Tropica or Zebra owners did not report any problems with making sharp corners. I wonder if the "electrical connection" between the motors is not the "straight axle mechanical connection" that you would suspect. Someone on the list help me here with a more knowledgeable explanation. A mobility chair or wheel chair has a controller or controllers that manage the speed and direction of the two drive wheels to control steering and movement. But did the Tropica (Zebra) circa 1996 have controllers that were just set up for forward travel, or was there some coordination between the units according to steering position and speed. A forklift technician may also know the answer. Do forklifts with steerable wheels need any coordination between two driving wheels. I suspect that the electric drive of the vehicles, not being 100% mechanical, gives enough flexibility for turning. Also, a drive axle with a differential with no locking device, can have one wheel lifted or lose traction, and the other wheel loses power because it is all transferred to the lifted wheel. I do not t hink this will happen with two wheels, each driven with an electric motor. One wheel with traction will keep transmitting power to the ground, and one that has lifted will spin also. However, now you have to make sure that you have the issue of over speeding a motor under control. The Tropica was listed with about a 60 mph top speed, 7" motor, 72 volts of batteries, and maybe the Curtis controller was set to limit top speed.
With one controller and two DC motors, each driving separate wheels, I would think that cabling them in series or parallel would affect the traction and speed of the motors. Someone more knowledgeable please jump in............................ Alan Part of post cut out.......... >The other potential problem is *not* having a differential. With a mechanical >differential, one wheel is allowed to turn faster than the other >when going >around corners. With hub motors, that process will have to be done >electronically. >Peri _______________________________________________ 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)
