[ElectricMotorcycles] Planetary Gear Reduction with Belt drive

[Andrew Wowk]

Hello,
I am at the point in my electric motorcycle project where I need to mount the motors and choose how best to transmit the power to the rear wheel. I am using two Etek motors which will be mounted horizontally opposed where the battery covers previously were (the motors will stick out the sides). The motors will be run at 72 volts while switched in parallel, and half that while in series.

Given the Etek voltage constant (72 rpm/volt) and the diameter of my rear wheel (26 inches), I want a reduction of atleast 5.5/1, and preferably as much as 6/1 or more. The top speed would not need to exceed 60 mph. The current controller used will be a 400 amp Curtis with plans to upgrade to a 600 amp Navitas at some point. The drive system I choose will need to handle a hell of a lot of torque.

Unfortunately the smallest drive pulley available with the etek shaft bore size (7/8 inch) looks to be large enough to where the driven pulley would need to be way too large. At any rate, the smaller the drive pulley the more tension the belt will need to handle. A possible solution may be to use multiple stage reduction.

A planetary gear set may offer a 3/1 reduction (though I'm not sure on this yet). If this is the case, than I would only need 2/1 reduction of the drive to driven pulley which means I can have a much larger drive pulley and a much smaller driven pulley with no trouble. I'm now considering automotive planetary gear sets.

The pulley drive system may be Browning's HPT (high performance timing) drive line.

Does anyone have any experience with planetary gear sets or tried this before? Any advise on belt drive systems? One major problem I can forsee is dirt getting in the planetary gear system. I don't know if pumping it full of grease would be a good enough seal, so I may need to somehow install seals. Also I don't know if there is a big difference between industrial timing pulley drive systems and those used in motorcycles. Any feedback?

Regards,
Andrew