I have been looking for a single gear reduction that might work. It's a
bit tricky since the driveshaft coupling must be sealed, so whatever I
use pretty much needs to be in a housing. So a simple jackshaft or the
like would be difficult. Using a transmission has two benefits: it mates
up perfectly with the driveshaft and it lets me play with several gear
ratios easily. But it takes up a good bit of room.
I'm thinking of a pancake motor. I believe Shawn Lawless had a Ural
conversion with two eteks in series.
The problem with direct drive is the gear reduction is only 37/11
(3:36:1) and the tires are large (18"?). The motor has to turn so slowly
at low speeds it will eat a lot of Amps to get the torque needed. So I
need a motor that can stand lots of low amps at low RPM. At the other
end I only need about 2000 RPM or so max, which would get me up near 50
MPH, which is fine.
I think I''l try to find a cheap tranny so I can get more data with my
current motor. That should provide me with the info I need to pick the
proper motor.
- SteveS
Jeffrey Blamey wrote:
My take: When I was looking for a donor bike I had considered the
airhead BMW. The area in front of the wheel just aft of where the
drive shaft exits looked like enough room for a PMG pancake motor (but
I never measured), the main issue would have been if the rotation was
correct for the PMG-132 and securing the drive shaft with a bearing so
you could use a sprocket. I was (am) sold on PMG for EMC. Over 1000
trouble free miles so far using a jackshaft so the PMG motor rotates
properly. Cheers. Jeff (BTW - my ICE bike is BMW)
On Fri, Feb 29, 2008 at 4:10 PM, Andrew Wowk <[EMAIL PROTECTED]> wrote:
Steve,
have you thought of experimenting with a planetary gear system to possibly
increase the gear reduction?
Regards,
Andrew in Albuquerque, NM
On Sun, Feb 10, 2008 at 1:47 PM, SteveS <[EMAIL PROTECTED]> wrote:
Took the bike over to the local high school parking lot today. I used a
push from a friend and a little downhill to minimize startup current. It
ran nicely at 20 MPH or so - about 100A battery current, 250-300A motor
current. I probably maxed out at 30MPH, but I have the Alltrax max
throttle set to 58% and a mechanical problem is limiting the potbox to
maybe 75% full travel. So say I get about 50% full throttle - sounds
about right. It's really really nice. Smooth, quiet, nice feel. This is
going to be good when I get it right. I guess I'm going to need a bigger
motor or gearbox though.....
- SteveS
