Regulator cut in UPDATE
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Category: Allis Chalmers
Forum Name: Farm Equipment
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URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=53963
Printed Date: 11 Sep 2025 at 3:33am
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Topic: Regulator cut in UPDATE
Posted By: D-17_Dave
Subject: Regulator cut in UPDATE
Date Posted: 21 Jul 2012 at 8:25pm
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What controls the cut in coil in a regulator
I got the wiring put back together on my D-15 diesel and I was amazed to find that when I manually closed the contact in the regulator it charged. It would not however cut out at idle or cut back in if I opened the contact. If I shut the engine off it would release but not induce once I restarted it. I'm not sure what the amperage was as I'm using combine gauges and the face only shows red/green. Voltage increase was about .5 volts over battery voltage. It maxed out at 13.2 volts.
I haven't cleaned or servised the generator and it has set for several years before I started this mechanical restoration.
I know Steve could answer this but he's been busy lately.
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Yea, I can fix that.....
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Replies:
Posted By: Gerald J.
Date Posted: 21 Jul 2012 at 9:32pm
How many contacts in the regulator?
One is the cutout and ought to be closest to the B and A terminals on the regulator and have the biggest contacts. The others are voltage regulator and current regulator if three coils and since the control the field current which is smaller than the armature current their contacts are usually smaller.
The generated voltage being greater than the battery voltage is what causes the cutout to close, so if it only got to 13.2 volts its not generating well and that may be why the cutout is not closing. It ought to get to 14.2 in the perfect regulator. Could be the brushes are worn down or the commutator dirty or both.
Gerald J.
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Posted By: D-17_Dave
Date Posted: 21 Jul 2012 at 10:16pm
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2 coil regulator which is mounted on top of the generator. 3 conections on the side, light/battery/field. The other wire from the gen comes in under the regulator. Since I haven't cleaned the gen and the brushes ark harshly under load the "dirty" diagnosis makes sense. I lightly pressed on the other contactor's spring to try to increase voltage and it would not increase. This tells me that something is maxed out, either the generator or the regulator's ability to induce the field. If I understand things right.
Thanks Gerald, that's a big help.
Next question is why pull the lights off the regulator. Seems like it would have more ability to recharge the battery by sending all the available amperage straight to the battery. as it is now the lights pull off a completly seperate loop straight from the regulator. Wouldn't I be better off replacing the regulator with that style setup to help with a lot of short run, start and stop work. This being an Industrial with a loader it'll get lots of short runs and low rpm's.
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Yea, I can fix that.....
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Posted By: Gerald J.
Date Posted: 22 Jul 2012 at 12:32am
The voltage regulator should be vibrating if its regulating. If its not vibrating its giving the field coil all it can because its not getting enough voltage. The spring tension is increased to increase the voltage setting.
Its possible that there are three windings on that magnet, one for voltage, one for lamp load to raise the voltage a bit to account for the lamp load, and a third to sample the armature current and back off on the voltage when it gets too high.
If the regulator only regulates charging, like many, the loads take current away from battery charging. When the engine is idling that can mean more current taken from the battery. Often a generator doesn't charge at engine idle, and so the loads are supplied by the battery. Worse at a slightly fast idle I noticed my '64 beetle with lab quality volt and amp meters, that the car would draw more current from the battery than it did at slow idle because it took several amps reverse current to cause the cutout to open. When I put a 12 volt engine in a 6 volt beetle, rather than change all the loads, I built a solid state regulator with a silicon diode for the cutout and eliminated that low engine speed reverse current. Battery life was noticeably better with the solid state regulator.
If the generator brushes are sparking, they probably are worn to the point that the springs aren't pushing them against the commutator and the commutator is dirty and getting more deposits from the arcing. Sounds like it needs the attention of a good automotive electric shop that remembers how to turn commutators and fit brushes.
I have cleaned up commutators with a commercial stick made for the purpose, some soft abrasive, but that won't fix short brushes.
Gerald J.
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Posted By: D-17_Dave
Date Posted: 22 Jul 2012 at 9:33am
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With the power steering pump in the way and at a glance, I only see the 2 brushes 180 degrees from each other. I've cleaned several myself, just in a hurry to see it spin up I went on and lubed it and installed it. I never thought it would charge at all. I'd say likely the brush holders are stuck in place so at the minimum it will need a good cleaning. Luck is I have a good shop that can rebuild it if needed. Just on a shoe string budget right now.
The cut in/out has a screw adjustment on it so I'm thinking this should let me fine tune the cut out to help eliminate the negative amp draw, but as you said before I have to establish a clean voltage field with enough rise to distingish the differance first.
Thanks again. Now I have something to do if I get bored.lol
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Yea, I can fix that.....
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Posted By: Gerald J.
Date Posted: 22 Jul 2012 at 11:41am
With a voltage regulator, there will be only two brushes. The third brush was used as a current limiter that allowed the same generator to charge 6 or 8 volt batteries but also allowed overcharge that had to be counteracted by turning on headlights in the day time to absorb the current the battery didn't need. Battery life is increased with a voltage regulator.
Gerald J.
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Posted By: Coke-in-MN
Date Posted: 22 Jul 2012 at 3:37pm
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http://chevy.oldcarmanualproject.com/electrical/49dr324/index.htm" rel="nofollow - http://chevy.oldcarmanualproject.com/electrical/49dr324/index.htm
might be some info on here that helps you figure it out
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Life lesson: If you’re being chased by a lion, you’re on a horse, to the left of you is a giraffe and on the right is a unicorn, what do you do? You stop drinking and get off the carousel.
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Posted By: D-17_Dave
Date Posted: 22 Jul 2012 at 8:14pm
Thanks Coke, that's always a help.
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Yea, I can fix that.....
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Posted By: Steve in NJ
Date Posted: 23 Jul 2012 at 6:50am
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Dave,
You might be better off upgrading to an Alternator for the "start/stop" senerio that the Tractor will be experiencing. The VR's in the "SI" series Alternators are very sensitive to voltage drops, so the Alt will keep on charging on an off idle better than a Gennie where you would have to increase the rpms more often to compensate for voltage being drawn from the Battery every time the machine is started. If you have sparks a flyin' around the com plate area while running, the arm will problably need to be serviced or replaced depending on the condition of the unit. If you want to keep the original look of the Tractor staying with a Gennie, it probably wouldn't be a bad idea to have a rebuilder go through the Gennie. Depending on the chassis, sometimes you can improve the Gennie's output with a field coil upgrade and a higher wound arm.
mailto:Steve@B&B" rel="nofollow - Steve@B&B
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Posted By: D-17_Dave
Date Posted: 23 Jul 2012 at 8:00am
I have to keep this style generator since it's a diesel the power steering drives off the rear of the gen.
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Yea, I can fix that.....
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Posted By: Brian Jasper co. Ia
Date Posted: 23 Jul 2012 at 10:13am
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I'm in that same boat, D17D has P/S pump on it too. Someone posted a while back there are 10SI alternators that had a splined output. I've never seen one, but I've also never looked for one either. I had my gen rebuilt with a new armature and a new sleeve from Norm. Do the old motor test on yours. Probably need to slip the pump off it. If it arcs a bunch and the brushes are not all that bad, you probably need a new armature. Mine worked fine when I took it off to overhaul the engine. It didn't work when I put it back on. Didn't do anything to it. Funny how that works...
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"Any man who thinks he can be happy and prosperous by letting the government take care of him better take a closer look at the American Indian." Henry Ford
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Posted By: Coke-in-MN
Date Posted: 23 Jul 2012 at 10:24am
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A old trick is to take a pencil eraser (preferably one for ink) and just run it on the commutator of the generator . It cleans them up nice and can be done while running, and solves many problems.
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Life lesson: If you’re being chased by a lion, you’re on a horse, to the left of you is a giraffe and on the right is a unicorn, what do you do? You stop drinking and get off the carousel.
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Posted By: D-17_Dave
Date Posted: 23 Jul 2012 at 8:58pm
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Update on this topic, I pulled the generator off and did a good cleaning. The brush holders were rusted stuck but the springs were OK as were the hinge posts. The brushes were OK, just needed polishing off the edge where they were arking. Armature I put in the drill and spun it up and cleaned off the comutator area. It cleaned up nice and straight and knocked off the glaze edges that run next to the stator. Lubed up the bearings and reinstalled. As soon as I fired it up the amp meter sprung up. I was presently surprised. What struck me odd was med. idle it came up strong but as soon as I raised the rpm past half or so throttle the meter stamered and dropped back bouncing. I adjusted the voltage coil up to near 13.5V and the meter raised to near full charge but leveled out steady across the rpm range. The cut in/cut out works well now too.
Question is am I wrong for uping the voltage making the gennie work harder? Why did increasing the voltage increase the amperage? Or did I just increase the field relay and amperage overdriving the generator?
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Yea, I can fix that.....
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Posted By: Gerald J.
Date Posted: 24 Jul 2012 at 12:15am
The optimum charging voltage is 14.2 volts. 13.5 is low for getting a full charge in the battery. If you have the voltage too high the battery current won't taper to zero. The SAE tolerance for that type of regulator was 13 to 15 volts being acceptable. I have a MF-135 and it was not charging well, though it had a new regulator when I got it about 1989. I adjusted the voltage and ever since it has charged better and still did last winter the last time I ran it.
Gerald J.
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Posted By: D-17_Dave
Date Posted: 24 Jul 2012 at 9:08am
I've seen regulators with 3 coils, they are/seem easy to adjust as I could up the voltage without disturbing anything else. I haven't ran it long enough to see if the amp meter tapers down. If I'm not hurting the generator I'll leave it like it is for awhile and watch it.
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Yea, I can fix that.....
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