Re: (ET) how does the late model I5 speed control work?

["Clean Power Supply" <cleanpower att net>]

 Chris,
 The E15's pulley is the smaller one at 3" while the E20 uses the bigger 
4" pulley. Consequently, the ground speed of the E20 is higher. Double 
check your sizing to be sure someone didn't swap them.
 If your E20 is drawing more current in reverse it is probably because the 
contacts in the F and R contactors are on the way out. 
 Internal construction of the E15 motor is almost identical to that of the 
E20. And while I didn't try to figure out the extra windings in those 
motors, keep in mind that it is in series with the armature and therefore 
on the E20 when the armature current is reversed to achieve reverse 
rotation the polarity of the extra windings reverses as well so any 
differences should be minimal.
 What I do know for sure is that the new D&D motor stands head and 
shoulders above the original in terms of raw power. Right, Mark? :-)
 Sincerely,
 Harold Z.
On September 5, 2012 at 8:56pm -0400, you wrote:
>Ok, I went out and floored it on my E20. Good wiring, newer disconnect,
>all power wires were cleaned and assembled, BB600 cells, fully charged.
>
>It goes right to full power, full field. You can hear the motor whine,
>it does not go into field weakening until the tractor is well underway
>and stable. Battery volts are in the middle of the meter, so it's not
>low powering out at the battery. All contactors engaged.
>
>Now the E20 has two differences from the E15: First the motor pulley is
>smaller so you get more power with less speed. Which can be made up for
>by the additional speeds. Second, the motor does have a compensation
>coil on the field that is *in series* with the armature. Thus under high
>power draws in forward it helps to strengthen the field and reduce the
>potential amp draw at the armature. I don't know/don't think the E15 has
>this.
>
>That might be the whine, the secondary field is limiting armature
>current. The drawback to this is that in reverse the tractor will pull
>way *MORE* current since the field is reversed and is acting against the
>natural field circuit. Ergo progressive field weakening. However since
>the high speeds are locked out in reverse this is only weird when going
>backwards up a hill in D2.
>
>Anyway, the E15 motor is much more jerky, I guess this is the lack of
>compensating field and larger pulley. Which would explain why they put
>that whole speed reduction thing in. The E12 has a similar motor so they
>put in the centri clutch.
>
>Chris
>
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