Converting DC electric tug to modern PWM control

848 Views 6 Replies 2 Participants Last post by legendre, Nov 3, 2017

legendre

Discussion Starter · Oct 29, 2017 (Edited)

Greetings folks, first post.

First off my complements to the membership - while it does exist, the sticky thread concerning perpetual motion / over-unity et al. is only three pages long.

But the main reason I'm here.. very good friend of mine has asked for some tech support in converting a 1960s era (my guess) industrial tug (I believe it's 24VDC) from the current brute-force solenoid & resistor control to a modern, progressive PWM control.

The stock unit has two controls - a level for Rev / Off / Fwd and one for High / Low speed - that's it. The control hardware consists of a very large pair of SPDT solenoids (relays) and an equally large power resistor. The resistor has a tap at 1/3 and I'd make it to be around 400W or so, and probably less than one ohm. Haven't measured it yet.

So how do we go about converting this old, inefficient control setup to a modern PWM type controller? This seems like it would be cakewalk stuff for electric car guys, so here I end up asking you folks. FYI a tug is a lot like a forklift without the fork - it's meant for pulling.. tugging stuff.. rather than lifting.

Any and all input is appreciated. Hope this isn't too far on the OT fringe... if it is, any suggestions on where else to ask?

Thanks in advance - from both of us.

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major

· #2 · Oct 30, 2017

legendre said:
Greetings folks, first post.

First off my complements to the membership - while it does exist, the sticky thread concerning perpetual motion / over-unity et al. is only three pages long.

But the main reason I'm here.. very good friend of mine has asked for some tech support in converting a 1960s era (my guess) industrial tug (I believe it's 24VDC) from the current brute-force solenoid & resistor control to a modern, progressive PWM control.

The stock unit has two controls - a level for Rev / Off / Fwd and one for High / Low speed - that's it. The control hardware consists of a very large pair of SPDT solenoids (relays) and an equally large power resistor. The resistor has a tap at 1/3 and I'd make it to be around 400W or so, and probably less than one ohm. Haven't measured it yet.

So how do we go about converting this old, inefficient control setup to a modern PWM type controller? This seems like it would be cakewalk stuff for electric car guys, so here I end up asking you folks. FYI a tug is a lot like a forklift without the fork - it's meant for pulling.. tugging stuff.. rather than lifting.

Any and all input is appreciated. Hope this isn't too far on the OT fringe... if it is, any suggestions on where else to ask?

Thanks in advance - from both of us.

Take a look at the manual for one of these units. You'll need reversing contactors to go with it.

http://www.alltraxinc.com/Products_AXE.html

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legendre

Discussion Starter · #3 · Oct 31, 2017

Thanks for that, those AXE controllers seem like they might well be the ticket. But I'm not sure what you mean by 'reversing contactors' - can you please elaborate on that?

The machine already is fitted with a pair of very large solenoids (relays) that govern fwd/rev operation. Is there any reason they cannot continue to be used in the new system?

Also, DC motors is not exactly my area. And unfortunately, the motors have almost no ID info on them, except that they are Square-D products. Each motor has four terminals marked A1, A2, F1, F2 connected to armature and field, respectively, and have field windings made of very heavy copper stap material, not many turns. Beyond this, they have no markings or other identifying info at all.

Are these 'series wound' motors then? Applicable to the controllers? Why are all of the terminals exposed when most DC motors have a simple +/- connection?

Again, thanks for any & all help!

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major

· #4 · Oct 31, 2017

Your existing F/R contactor's may work with the new controller. The manual has the wiring diagram which will clue you in.

You're likely talking about PM DC motors with 2 leads (terminals) which are reversible. Wound field DC motors (such as series motors) require 4 terminals to reverse. You must reverse the armature relative to the field or vise verse, but not both. Again the manual wiring diagram will show this.

Oh, a contactor is just a big relay, often called a solenoid in automotive lingo. And it does sound like you have a series wound motor.

major

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legendre

Discussion Starter · #5 · Nov 1, 2017

If that's a pic of you on the Bonneville flats, then you have something in common with my friend who I'm helping out.. he runs in the 1000cc pushrod class with a heavily modified HRD Vincent Rapide.

Roger on the series wound motor. And you'll have to forgive me, but I don't seem to find the manuals for the Axe controllers on that site. I must be overlooking them.

Friend came across these controllers: Kelly KDZ24400 & Curtis 1204m. Are these also applicable? Know anything about them?

Thanks for your input. We're both technically capable, but neither of us have done this type of job before so we want to make sure we've got the knowledge before throwing the money down. I'm sure you understand.. ;-)

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major

· #6 · Nov 2, 2017

Go here for manuals and diagrams.

http://www.alltraxinc.com/Doc_Depot.html.

Curtis is good, maybe better than Alltrax. I thought for a new one Alltrax might be less costly. Kelly sucks big time... Avoid Kelly.

That would be Paul, our pilot. I was crew. Set a few FIM records for electrics with that bike.

major

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legendre

Discussion Starter · #7 · Nov 3, 2017

Roger that. So.. what's the deal with Kelly? Just a general bad rap, or have you had more personal experience with that brand?

And boy was I wrong.. I just noticed that the PM thread is 175 pages long. Oh well, can't blame you I guess.. sometimes you just gotta dream.

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