Re: [ElectricMotorcycles] Planetary Gear Reduction with Belt drive

[Andrew Wowk]

Thanks a lot for all your comments.

I am awar of the fact that the belt or chain will neeed some type of tensioning idler pulley/chain with a light spring preload. Does anyone know of a good source for chain/pulley tensioners?

Shawn,
Thanks for the parts source. Your comments made me reconsider using a chain drive. I drive a BMW gas motorcycle w/shaft drive so I don't have any experience with chains on high power bikes. I thought they would be quite loud.

Paul,
I think Damon is right. My dad has a converted Yamaha with a shaft drive ADC motor which is geared 3/1 to the rear wheel which is way to high, but the motor may still not be running horribly inefficient. Cruising at 50 mph its sucking alot more than 40 amps, probably around 100+, and it is running on a 72v system. Just curious, what kind of range do you get? From my estimates your bike probably gets about 10-11 miles range, is this correct?

Mark,
I thought of this, and agonized over it for a long time. In the end I decided to not use a jack shaft because of how much battery space it will take up. The pack will be large enough to store 4.32 kwhrs nominal and I have just enough space to stuff the batteries down low where I want them. In addition this adds an additional sprocket, chain, and bearing. However, since I'm considering a planetary gear system which would certainly add complexity I might as well reconsider this idea again.

At first I thought that the belt/pulley being very loose and hanging would not be a problem to accomodate the rear wheel vertical movement as I go over bumps. However, if I'm coasting (or not applying power) and hit a steep hill where the rear wheel is actually driving the motors than the chain will tension at bottom and slacken at top which would cause problems real fast. To solve this I'd need a ratchet type mechanism like the kind on bicycles. I don't know where I could find one large enough or even if I want to bother going down that path. If I had one, than it seems in theory that I wouldn't need a chain/belt tensioner and maybe this would make the bike more efficeint too.

I don't know what is so inefficient about a planetary gear set. It seems quite simple. Added weight would not be good , but than through using one I could reduce the weight of a large rear sprocket/pulley.

I could sell the eteks I bought and buy two Perm PMG 132 motors. At 50.2 rpm/volt this would make gear reduction a bit easier at the cost of an additional 1.2k (after etek sale). Not very appealing given my budget.

Regards,
Andrew