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1920s Delco Circuit Breakers


ryan95

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I am working on restoring a Delco combination switch for a 1923 Moon. It is basically the same switch as Buick used and probably many other makes of the time. It is the round pot metal one with two levers and a glass face. I am currently trying to figure out what I can about how to make the breaker work right. It also looks like Delco produced similar breakers that mounted just on a panel. Someone on here in an old thread posted a picture with them on their 1924 Cadillac. There isn't much information on them that I can find other than the current they are designed to operate at. From what I can guess by looking at them, there is a set of points, that are normally closed, that are forced apart by a plunger pulled upwards by an electromagnet when the current gets too high. This is my guess, not necessarily how it actually works. I have heard other ideas too from others who work on these, but want to hear what others can contribute too. I think I have a part missing since my plunger runs out of travel before it can reach the upper contact. If anyone can give any more info on these or pull one off their shelf to examine it, I would be grateful.KIMG1235.JPG.c94b1e86c477d2263234925aa5a500af.JPG

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I'm considering that route as an option. I do like the concept of the vibrating breaker though. It doesn't seem that they break the current until reset like modern breakers, but rather limit current and alarm you that there is a problem that needs addressed.

Edited by ryan95 (see edit history)
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  • 3 weeks later...

I have the same vibrating circuit breaker in my 1928 Graham-Paige.  The car runs and starts fine on the 6V battery, when you turn on the headlights the circuit breaker... well vibrates, If I read correctly I have a dead short?  and the circuit breaker is working just fine??  I thought the breaker was going bad?  Amperage gauge looks, good it only happens when I try to turn on the lights.

Edited by Graham Man (see edit history)
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Peter, that's a wealth of information. Thank you for sharing. The switch is a 1238. I think I'm making progress on it. Either I have a missing piece or someone filed the plunger too short. The plunger at max travel doesn't go higher than the bottom contact. You can see that in the first picture. My solution until I have a better option is I made a little plastic piece that sits on the top of the plunger. Maybe I need to make a new one that is long enough. It is now vibrating once it reaches 30 amps. What ideas do you have based on your experience?KIMG1240.JPG.8a4fc2bbc09aa3529ca05450846b2766.JPGKIMG1249.JPG.ee06225cf49e89ceb0118d375efe9474.JPG

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Looking over all the technical info I am pretty sure that the plunger was shortened too much at one point. I was able to punch enough of the brass part out to get the extra length needed for the .012 gap spec. It now works as designed. 

 

I also wanted to rewind the magnet since the paper like 1920s insulation was in poor shape. I used 14awg solid core wire I found at the hardware store. The original looks to be 15 or 16 gauge, so it should have no problem carrying the current. I was concerned that being thicker I wouldn't be able to get 10 windings like original. I stripped off the clear layer to get it a little thinner and was able to get 8 windings. It has no problem pulling the plunger with 2 less. It will get a final adjustment when I have a 6v source to test it, but I finally feel pleased with how it is working. I'm glad to say that I'm moving on with the switch to making a new phenolic contact plate.KIMG1259_01_BURST1001259_COVER.JPG.091ca08e765aea09beadf38de3b5a9eb.JPGKIMG1260.JPG.9aa4d259f3d10c90b95530d16add71b5.JPGKIMG1261.JPG.2d926927fc7367b953ed344d8c8abfdb.JPGKIMG1262.JPG.d8359a3a32134dadc93bb6652a02ea52.JPG

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