Curtis controller voltage rating?

[jdunmyer]

The other day, I found a golf cart at the scrapyard, it appeared to have trays for 4, 6-volt batteries, IE: 24 volts. It had what appears to be a Curtis 1204 or 1205 controller, so I grabbed it. The label says "Taylor Dunn", and "24 volt", I don't remember the current rating, but IIRC it was at least 250 amps.

The Curtis controllers that I've gotten from other scrapped carts were mostly 36-volt rated, maybe one was 48, but I'm unsure. What's the odds that this controller will work OK at 36 volts?

If it's still there on my next trip, I think I'll grab the motor, as it's a belt-drive configuration. Might be useful for something down the road. Also will have to look for the pot box to see if I can easily extract it.

[JohnnieB]

Here are a couple manuals you'll probably find interesting. Specs are on the last pages of each.

[jdunmyer]

Hmmm... I should have looked at the manual first, I actually have a copy on my computer from the days when I converted my old CC.

I see that my controller is either 24-36 volts or 36-48 volts. It must be the former, as it was on a 24 volt cart. Good to see that it'll work on 36 volts.

Somewhere on this forum is a thread asking about connecting a 12 VDC winch to a cart, and I think he wants to use a controller of some sort to provide the low voltage from his main pack. I have a similar need:

I have a GE Elec-Trak garden tractor that I'd like to use a hydraulic power unit to lift the snow blade. GE used a GM window lift motor for an implement lift, and that works fine for mowing. Not so much for snow plowing, where you're operating the lift a LOT. It heats up and quits before I get my drive plowed. My stockpile of junk includes a small hydraulic pump, coupled to a motor that I think is 12VDC (haven't looked closely yet). My first thought was to exchange the motor for a deck motor, as those are 36 volts and about 1/2 HP, but it might be easier to use a controller.

Another project is to convert a tractor to a controller and eliminate all the solenoids and micro switches. Although I have a known good Curtis 1205, it won't provide field weakening for the higher speeds, but Altrax actually sells a special version just for the E.T.

Thanks for the tip!!

[JohnnieB]

Originally Posted by jdunmyer

Another project is to convert a tractor to a controller and eliminate all the solenoids and micro switches. Although I have a known good Curtis 1205, it won't provide field weakening for the higher speeds, but Altrax actually sells a special version just for the E.T.

Sounds like the tractor has a SepEx drive motor, but what kind of amp delivery system does it have?

I cannot visualize a SepEx system with multiple solenoids and microswitches.

Got any schematics, wiring diagrams or pictures?

[jdunmyer]

JB,
Here's the service manual: http://www.myelec-traks.com/GEZ-5021b.pdf, all other manuals are at: http://www.myelec-traks.com/Publications.html

Basically, the speed control energizes the field, then the armature, the latter through 2 resistors. The field voltage goes through a bank of (much smaller) resistors that are shorted out through microswitches on the "throttle". As you advance the speed control, power goes through the big "toaster" resistors. Advancing the control further results in 2 solenoids/relays successively shorting the toaster resistors, then picking up the field weakening relay. The next speed selection has a micro switch un-short a field weakening resistor, then there's 3 more steps. Total of 7 speeds forward, only 2 or 3 in reverse.

I believe the motor will draw over 100 amps, but the meter is calibrated in "Green, Yellow, and Red". It's not nearly as powerful as a golf cart, but the motor drives a 4-speed transmission, so you select the appropriate gear for the load. Believe it or not, people pull a turning plow with the E.T.

The forum that I use the most is: http://ge-electrak.com/, the guys are as helpful there as the fellas here are.

I've taken my E16 to one tractor show so far, and will show it several more times this Summer.

[JohnnieB]

Basically the 60's electromechanical version of the 80's electronic speed controller for a SepEx motor.

Installing the controller you said Alltrax makes for it, would make it a lot more efficient and would probably increase run time considerably, but doing so might be blasphemy to the purists.

Fortunately, I've been exposed to schematics drawn by GE before and can read then.

[jdunmyer]

jb said:

Installing the controller you said Alltrax makes for it, would make it a lot more efficient and would probably increase run time considerably, but doing so might be blasphemy to the purists.

I won't consider a conversion for my E16, as it's very, very nice, and works well. It does drive me crazy to plow snow and think of that little window lift motor working it's heart out, and the clacking and internal arcing from the solenoids. I have an E20 with screwed up electrics that I want to convert to a controller; the guy I bought it from had the same idea, but didn't get a Round Tuit.

The manual for the ET recommends that you operate mostly with the speed control in "third", which has the toaster shorted out, but no field weakening. This is pretty easy to do while mowing.

Actually, if all I did was mow with the ET, I'd probably not consider a conversion, but all I plan on doing with them is plowing snow and exhibiting the E16 at tractor shows.

The ET forum that I referenced has a "controller conversion" sub-forum, and one fella describes using a Curtis 1204 controller. I've not followed up to see how/if he did any field weakening, I think he just skipped that feature. I also don't know if the Alltrax provides that or not. One of the vendors sells a complete conversion: controller, pot box, heavy-duty solenoid, and full instructions. That's very tempting to me, as it would save a bunch of engineering time.

I do have the controller described above, and a known-good Curtis 1205 that I removed from my scrap CC. Those are tempting, just for the price, and I am familiar with their operation from the CC conversion.