Re: [ElectricMotorcycles] Planetary Gear Reduction with Belt drive

[Mark Thomasson]

Andrew,  Some more thoughts on this.  Sounds like you are mounting the motors in a place that will cause the drive chain or belt tension to vary drastically with rear suspension movement.  You need a well designed tension adjustment system to keep the chain from falling off the sprockets, or the belt from slipping.  A planetary gear set will add weight and lots of complication.  One way to solve the gear ratio problem and the chain tension problem together is to use a jack shaft (I think that's what they're called) mounted with a sprocket where the original motor sprocket was positioned.  The Eteks would drive the jack shaft and the jack shaft would drive the wheel.  Somewhat greater losses using two chains, but probably not as much as the gear box.  Getting the 6 to 1 or greater reduction would be easy.  The jack shaft takes up a little space where you would like to put batteries, but not as much as mounting the motors there. I have the same problem with my bike, currently 15/67 tooth sprockets, direct drive, 48 volts, 45mph top speed.  I want to go to 84 volts, but I'll need a larger rear sprocket to make the most of it, but I don't have enough clearance in the frame.  The jack shaft thing would solve this problem and give me more room for batteries in the lower frame.    Mark T.  ----- Original Message ----- From: Shawn M. Waggoner To: 'ElectricMotorcycles' Sent: Tuesday, May 23, 2006 9:31 PM Subject: Re: [ElectricMotorcycles] Planetary Gear Reduction with Belt drive Hi Andrew,   Shafts and fixed drivelines require a lot of alignment and present a unique problem when the motors are fixed to the frame and not the swing arm. The travel in the rear swing arm will create different angles on the driveline at different points of travel.   On every bike I have built so far, I have used a chain drive. It is simple, easy to work with and more tolerant of the torque. Some folks may not like the chain noise, but if your sprocket alignment is accurate and use a good roller chain that is properly adjusted, it is very minimal. A good source of sprockets and chain is the Surplus Center (www.surpluscenter.com). For a dual ETEK setup, I would use at least a #40 chain.   Good luck!   Shawn   From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Andrew Wowk Sent: Tuesday, May 23, 2006 10:08 PM To: ElectricMotorcycles Subject: [ElectricMotorcycles] Planetary Gear Reduction with Belt drive   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