Re: (ET) Speed control

["David Roden (Akron OH USA)" <roden ald net>]

On 7 Jan 2002 at 21:13, Christopher Zach wrote:

> What kind of speed control do the elec-tracs use? Variable volatge on the
> field windings? Stepped volatges off the batteries? Big hunking resistors
> (I hope not, the waste!)? Primitive pulse based throttle?

Depends on what model.  

The E8/10 I believe had ~no~ speed control -- you just turn on the motor 
and when you want to go you engage the clutch.  You get different speeds 
by using a transmission.  This is the way my ER-36 mower is, and it's 
utterly silly.  GE essentially just dropped a motor in place of the 
engine on a gas rider mower, and failed to utilize the motor's great 
advantages -- that it doesn't need to idle, and that it needs less in the 
way of a shiftable transmission (and no reverse gear).

The E12 has 3 speeds.  The first two speeds put big nichrome ribbon 
resistors in series with the armature.  This is similar to old-fashioned 
resistor golf car controllers.

The E15 has 7 speeds derived similarly, but with field weakening for the 
speeds above #3 or #4.

The E20 has 8 speeds and I believe it is similar to the E15, using field 
weakening, though I haven't looked closely at one.  It has a foot pedal 
instead of a hand lever.

There was no battery tapping for speed control (as far as I know), and 
I'm pretty sure neither GE nor WH ever fitted PWM choppers to any model.


David Roden - Akron, Ohio, USA
1991 Solectria Force 144vac
1991 Ford Escort Green/EV 128vdc
1979 General Engines ElectroPed 24vdc
1970 GE Elec-trak E15 36vdc
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