Voltage regulator

[fixitflav]

I’m looking for a voltage regulator for an American-built tractor. Problem is, it’s for a dynamo where the field winding is commoned with the dynamo output (D terminal) inside the dynamo, and the trembling regulator contacts are on the earth side. I believe that’s called a Type A regulator. (Much more common in UK, the field is earthed in the dynamo and fed with voltage from the regulator. Presumably that is Type B. That type is readily available 2nd hand)

Dynamo and original regulator are 12-volt AC-Delco. Anybody know where I can get one? Or what vehicles in UK used AC-Delco electrics? I believe earlier Vauxhalls is one.

I got one from USA via Amazon and it is useless. If connected it would cause a short circuit, and the voltage coil in the cut-out bobbin is not connected! Probably Chinese-made. Sent it back and waiting for a refund. Very crude sketch attached.

Any help appreciated.

 

[ericmark]

The French also did it reverse to Lucas, Paris Rhone etc.

The problem is the current regulation, many tractor dynamos were only rated 11 amp as no cooling holes.

But Lucas was the odd one out, with the Lucas system you could polarise the dynamo easier, than with the other systems.

 

[fixitflav]

The French also did it reverse to Lucas, Paris Rhone etc.

I wasn't aware of that, might be useful

The problem is the current regulation, many tractor dynamos were only rated 11 amp as no cooling holes.

That's right, the dynamo has no cooling holes. Typically with a 2-bobbin regulator it's adjusted to 16-16.5 volts (if I remember right) on no load (disconnect everything but ignition) and max current is what it is. If I got hold of one and the current was a more usual 22 amp I could reduce the voltage setting, and measure max current. I don't think it would be a problem in practice. Better still if I could source a 3-bobbin regulator, where voltage and current settings are adjustable independently. If available as Type A, field earthed via regulator, type.

But Lucas was the odd one out, with the Lucas system you could polarise the dynamo easier, than with the other systems.

That's right, with this type you can't polarise the usual way, by flicking 12 volts on the F terminal, as it's commoned with D and is as good as a short to earth. What I did was lift one of the brushes off the commutator, then put 12 volts on the D terminal, and flick a wire from F to earth..

 

[ericmark]

I had many of the old work shop manuals, but laying my hand on them now, more of a problem, from the third brush and free wheel most dynamos had some current regulation, also some alternators, the CAV 203 for example, designed mainly for buses to charge at tick over.

There were some odd ideas like bucking coils, to remove some residual magnetism to stop over charging, but rather rare.

Even found a duel output alternator 12 and 24 volt used with a Grove crane. The French and USA alternators and Dynamos were often interchangeable,as both fitted to CAT tractors, but the French method to have brush-less was very different to USA, for their alternators. Neither using the methods used with larger static versions.

The French used single phase alternators, some just two diodes and a fuse, some three diodes, and the alternator warning light would never go out, so they used a dark glass on them.

On the Falklands where spares were in short supply, I used a bulb holder and fitted a 18/21/36 watt bulb to adjust output, bit hit and miss, but kept the plant running.

The replacement Lucas regulators from Gordon Equipment also called Durite used diodes instead of contacts to so dynamo motoring, have you looked on Durite web site, they may make a regulator which will suite your needs.

 

[fixitflav]

Durite web site, they may make a regulator which will suite your needs.

Thanks, I hadn't heard of them but I'll give them a try

 

[ericmark]

I left the auto electrical trade many years ago, around 1990, I sidewards moved to low voltage (50 - 1000 volt AC) although the electrohaul truck was from memory 11kV so auto electrics did involve high voltages with some applications.
It seems some trucks do use high voltages! And I saw the problems testing ignition systems by touching the spark plugs when using capacitor discharge, he survived, but more by luck than good judgement.

I volunteer at local railway, and looking at some dynamo systems

One starts to realise how complex they can get, when one returns to the age of steam. I decided to keep my back ground undisclosed as not sure I could work with that!

 

[jj4091]

Don't know if this helps AC Delco old vehicle dynamo voltage regulator one company seems to offer a conversion service & there seems to different models on Amazon, but not from UK unfortunately

 

[fixitflav]

Don't know if this helps AC Delco old vehicle dynamo voltage regulator one company seems to offer a conversion service & there seems to different models on Amazon, but not from UK unfortunately

Thanks for that, it shows plenty on eBay and one might be suitable. Can't be any worse than the one from Rare Electric, via Amazon!
Interestingly, there are also loads of pictures of Lucas 2- and 3-bobbin regulators of type which used to be very common in UK before alternators came in. These were for internally earthed dynamos. But the wiring diagrams that came up nearly all show externally-earthed, like I need. So a lot of care needed!
Also on there is a Delco-Remy service bulletin, and under dynamo polarising it says
POLARIZING GENERATOR
After reconnecting leads, momentarily connect a jumper lead between the "GEN" and "BAT" terminals of the regulator. This allows a
momentary surge of current to flow through the generator which correctly polarizes it. Failure to do this may result in severe damage to the equipment since reversed polarity causes vibration, arcing, and burning of the relay contact points.
CAUTION:
If a fuse is located on the regulator, polarize the generator by momentarily placing a jumper between the "GEN" terminal and the screw on the fuse to which the lead is connected. If the other screw on the fuse is touched, the fuse may blow.

That sounds a bit cowboy to me. Doing it my way, lifting one of the brushes, puts the current through the field, as required, but doesn't risk blowing fuses or overheating.

 

[ericmark]

A blocking diode (looks like an ignition coil) can replace the cut out, only need regulation, I tried using wrong makes of regulator when I could not get correct one, the problem is they use different currents, so one can use one designed for higher current but not a lower current.

But the big question is how long do you use the tractor for? and does it need lights? For shows you can likely select a bulb which will cause it to charge enough not to go flat during the day, and likely you only use the tractor for shows so would start off with fully charged battery.

The problem is getting it to look right, hiding the bulb acting as a resistor where it can't be seen.

 

[fixitflav]

It's my brother's tractor, and it is mainly used for shows, so it's not an urgent problem. It has lights.
On the website I mentioned, there were circuit diagrams for 3-bobbin externally-earthed regulators. That would be ideal, enabling independent voltage and current settings. Unfortunately there was no way to actually buy one! I've never seen one in the flesh, but worked on plenty internally-earthed.
eBay has several, all looking much like the Amazon one, and as the attached pic. One said made in USA so hopefully built properly, but not sure it's worth taking a chance buying another.
What we'll most likely do is change the dynamo for an internally-earthed one, and use a conventional UK control box, have several kicking about. But it's not straightforward as it's an unusual layout, the pulley has a long overhang, so will need a special bracket making up.

Thanks for your comments. I emailed Durite, no answer yet but I'm not hopeful.