E 20 control system

E 20 control system

Postby ram1450 » Mon Jan 18, 2016 8:15 pm

I would like to hear opinions about changing the control system of an E20CA that I inherited many years ago to the system of the later EA and FA models. I also have an E20FA since it was new and it has been a workhorse for me with mower and snowplow, and I love it. I've had very good luck with it as far as reliability.
My CA model has not been as reliable, but it had very hard use before I got it. Recently one of the double contactors went bad and I had to replace it and its partner with single ones which I got from Harold Z. His insructions mentioned the very abrupt stop when the controller pedal is released. Abrupt is a mild description of what happens when you are in 2nd or 3rd gear and you take your foot off the pedal.!! He also included a suggested alternate set-up that allows the power to be dissipated through the resistors. I haven't yet done that rewiring, but thought I would like to hear suggestions from the group what they think about redoing the operating system to the more modern one. Because my lot is all hills, I don't think the Alltrax system is right for me.

Thanks. Rob Max ;)
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Re: E 20 control system

Postby Jeff Antonucci » Tue Jan 19, 2016 5:43 pm

I see no issues with going to the later model control system. The later the tractor the more reliable is the ground rule. I also don't see why you would shy away from using an Alltrax. They are better in every way in my opinion. More efficient and more powerful. My E20 with Alltrax was an absolute beast. I wish I had it back for winter snow plowing!
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Re: E 20 control system

Postby roberttroll » Tue Jan 19, 2016 5:45 pm

Why don't you think a digital controller it is right for you?

Last time i looked - it is cheaper to swap out a controller. Depends on what you have for spares.
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Re: E 20 control system

Postby ram1450 » Thu Jan 21, 2016 4:30 am

Hi,
Thanks for answering. Several years ago I was told that the Alltrax did not have braking effect going downhill. Most of my yard is a 10 to 15% grade, and given the brakes on my tractors, I didn't want to have my own home roller coaster. I have been able to use the drag from the motor as 4/5 of the braking I need, with both tractors.
RM
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Re: E 20 control system

Postby EtnaInst » Sat Jan 23, 2016 6:13 pm

One difference between the earlier E20 models (AA-DA) and the later ones (EA-FA) is the way the contactors are configured. In particular, the later ones, using the 6-terminal contactors, will short out the motor armature when the speed control is in the "off" position. However, since the field is not powered in "off", the motor will freewheel, providing no braking effect at all. (We'll, there is a bit of mechanical drag, but it isn't very much).

A simple wiring change will provide a rather dramatic dynamic braking effect. Connect a suitable diode (1N54xx type) with its anode (non-banded end) at wire #8, where the drive motor A1 connects to the 2A contactor. Connect the cathode (banded end) to wire #28, the junction of the two diodes that supply power to the motor field. That will energize the field even when the speed control goes to "off", as long as the motor is already turning; it will then act as a generator that is shorted through the two toaster resistor elements.

If you want to get fancy, use a SPST switch to make or break this connection, so you can turn dynamic braking off or on. It is rather abrupt, but on my hilly property that's a feature, not a bug!

This also works on the later I-5 models (CA and DA). It *should* also work on any machine with a shunt motor (not permanent magnet) that uses the 6-terminal contactors.

That reminds me of another aspect of those 6-terminal contactors. They are wired up as a SPDT switch. The normally-closed contacts provide the connection from the motor to the negative side of the battery; so, the R contactor's normally closed contacts carry current in Forward, and vise-versa. Those contacts are held closed by a spring (and gravity?) and are more likely to fail than are the normally-open contacts that are closed when the contactor's coil is energized. As a result, the R contactor is more likely to fail than the F contactor, and so you are more likely to loose Forward than Reverse!
Larry Chace, Ithaca, NY I-5 and E15
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Re: E 20 control system

Postby roberttroll » Sat Jan 23, 2016 10:15 pm

You should be able to have regen/braking with a 4QD controller.
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