# "two stage" direct drive?



## Ziggythewiz (May 16, 2010)

How are you going to disconnect the little motor when you switch to the big one?


----------



## DIYguy (Sep 18, 2008)

Aelwero said:


> Still in the "brainstorming phase" and trying to decide between gearbox and direct drive. Direct is attractive because I currently have an auto tranny, and would have to install the entire clutch workings in addition to the gearbox.
> 
> I believe I understand the "low speed" drawbacks thanks to this forum, and I had a "gee whiz" moment on it... what if you were to use a smaller "startup" motor instead of a lower gear? I'm picturing a double output motor, a yoke on one end, and a gear on the other (or a chain/belt drive), to be mated to a gear on a smaller motor that can torque up to efficient RPM at very low speed. Instead of shifting the gears in a transmission, you would shift from the "low gear" motor to the "high gear" normal EV motor...
> 
> Thoughts?


Just get the differential ratio right and go with an overdrive like the GV. Much more elegant solution.


----------



## Aelwero (Aug 24, 2010)

an electric solenoid seems like a shoe-in. been done on IC engines for a hot minute... I'm pretty confident I could adapt a conventional IC solenoid assembly to a larger motor, but I have no idea if it's an "energy efficient" way to negate a gearbox... I'm more a fabricator than an electrician.


----------



## Salty9 (Jul 13, 2009)

Have you checked Mizlplix's threads on the powerglide?


----------



## Woodsmith (Jun 5, 2008)

DIYguy said:


> Just get the differential ratio right and go with an overdrive like the GV. Much more elegant solution.


I would go this way if you didn't want a full transmission.



> Have you checked Mizlplix's threads on the powerglide?


This would be worth a look too.

Adding a second motor isn't a 'nice' solution as you also have the high current electrical connections from the controller to swap over. That puts four change over contactors in there as well.
Also when the high speed motor runs it could over speed the low speed motor and associated components.

An alternative could be a small two speed transfer box, say from a Suzuki 4x4, that will give you two speeds in a compact package.

When I was modeling my trike I determined that, at the time, I would be doing so few low speed miles that I could bear the loss of efficiency running an 11" motor at less then 1000rpm to get the 1/2 mile to the motorway at each end of a 35 mile commute.


----------

