Enfield Engine - Rectifier.

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colinlewis

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Hi I have an Enfield Mark 3a twin cylinder air cooled diesel engine with a built in AC generator 12v probably Two wires coming out to a rectifier to give out 12v DC.I am pretty sure rectifier is faulty.Does anyone out there have one ? It is rectangular about 3in by 4 in any about 1\4 in thick.If not could someone recommend a replacement is make and model number? Thanks for looking. Colin
 
Enfield engine-rectifier

Hi I have an Enfield Mark 3a twin cylinder air cooled diesel engine with a built in AC generator 12v probably Two wires coming out to a rectifier to give out 12v DC.I am pretty sure rectifier is faulty.Does anyone out there have one ? It is rectangular about 3in by 4 in any about 1\4 in thick.If not could someone recommend a replacement is make and model number? Thanks for looking. Colin
 
Re: Enfield engine-rectifier

colinlewis said:
Hi I have an Enfield Mark 3a twin cylinder air cooled diesel engine with a built in AC generator 12v probably Two wires coming out to a rectifier to give out 12v DC.I am pretty sure rectifier is faulty.Does anyone out there have one ? It is rectangular about 3in by 4 in any about 1\4 in thick.If not could someone recommend a replacement is make and model number? Thanks for looking. Colin
Click to expand...

If you have any idea of the max current rating pick one of these http://www.maplin.co.uk/search?text=bridge+rectifiers&x=19&y=13
 
colinlewis said:
Hi I have an Enfield Mark 3a twin cylinder air cooled diesel engine with a built in AC generator 12v probably Two wires coming out to a rectifier to give out 12v DC.I am pretty sure rectifier is faulty.Does anyone out there have one ? It is rectangular about 3in by 4 in any about 1\4 in thick.If not could someone recommend a replacement is make and model number? Thanks for looking. Colin
Click to expand...

If you know what max current to expect one of these will do the trick http://www.maplin.co.uk/search?text=bridge+rectifiers&x=19&y=13
 
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Re: Enfield engine-rectifier

colinlewis said:
Hi I have an Enfield Mark 3a twin cylinder air cooled diesel engine with a built in AC generator 12v probably Two wires coming out to a rectifier to give out 12v DC.I am pretty sure rectifier is faulty.Does anyone out there have one ? It is rectangular about 3in by 4 in any about 1\4 in thick.If not could someone recommend a replacement is make and model number? Thanks for looking. Colin
Click to expand...

3" x 4" x 1/4" thats not a case style I have ever seen..
A picture would hep identify it.
 
Re: Enfield engine-rectifier

Two threads combined to keep info flow in one place.


Also to show how much we value VicS' contributions :) Twice the exposure !


Moderator
 
Re: Enfield engine-rectifier

Moderator said:
Two threads combined to keep info flow in one place.


Also to show how much we value VicS' contributions :) Twice the exposure !


Moderator
Click to expand...

I had not realised there were duplicate threads . I wondered where my reply had gone! I assumed id forgotten to hit the post button...... again :(
 
Re: Enfield engine-rectifier

This must be a very old one. My only experience of the air cooled Enfield twins were when they were fitted to naval whalers and emergency fire pumps and I've not seen one working since around 1967. They were replaced in the RN emergency fire pumps by climax petrol engines and again by Rover gas turbines. The Rover Pumps were just being introduced around '68, I think but I'm sure a naval historian will be around to put me right on that. I can't help with the generator but If it's ExWD, there should be an identification plate on it that'll help lead to the necessary details about the rectifier. You might then ask HMS Sultan for a bit of assistance.
 
A bit off beat but a rectifier is a rectifier. On my old British motorbike, i replaced the non working one with a solid state one from RS or Maplins. The old one was a chunky metal item with fins, the new one a tiny plastic thing. I was concerned about the heat dissipation but it wasn't a problem.
 
I'm coming to this a bit late, but the alternator is likely to be a Lucas motorcycle type one.

If it has two wires, single phase with a permanent magnet stator.

The wires should show between 35-65 volts ac if it is working ok.

If it tests ok, I would suggest a Boyer-Bransden recifier/regulator.

Simple and foolproof to fit-the two yellow ires to the two alternator wires, red to battery pos, black to battery neg.

By using the Zenner diode as a chopping diode on every output sine wave it controls voltage to a maximum of 14.5v dc after rectifing the 35-65v ac.

Much better than the stock 1960's system and far more reliable.
 
rotrax said:
I'm coming to this a bit late, but the alternator is likely to be a Lucas motorcycle type one
Click to expand...

Probably something a bit meatier than a bike type. The Fire pumps were very powerful and I'd guess (and it's only a guess) that there's be an AC take off and the rectifier would be for DC. I think it unlikely that the Enfield twin would be solely use for DC, unless it's just to charge a battery. The one's on the Whalers and fire pumps were hand cranked.
 
Topcat47 said:
Probably something a bit meatier than a bike type. The Fire pumps were very powerful and I'd guess (and it's only a guess) that there's be an AC take off and the rectifier would be for DC. I think it unlikely that the Enfield twin would be solely use for DC, unless it's just to charge a battery. The one's on the Whalers and fire pumps were hand cranked.
Click to expand...

Yes-thats what rectifiers do, only allow current flowing one way out-DC.

You have lost me with your other comment-I am sure the alternator IS purely for battery charging.

If the fire pump was very powerful it would need something a bit better than an Enfield flat twin diesel to drive it......................

IMHO, of course.
 
The Enfield pumps were "portable" fire pumps used on naval vessels. A pose of burly seamen would carry it close to the source of the fire start it up and run the hose to the actual site. It was routine to have two men on the hose as they had high volume pumps fitted. They had no need for electrics and OK it's ~ 50years since I worked on one, but I don't remember the ones in the whalers having any electrics either. The Climax Portable fire pumps had electric starts and batteries so they'd have had a small alternator but the Rover Gas Turbine version that succeeded the climax was light enough to be carried by two men. They were quite exciting to watch fired up, too.

This is a digression, however, I opined that the generator was unlikely to be a motorcycle one if the enfield was the power source of a "portable" generator as it would be likely to have an AC takeoff too.

Found this on U-tube, just as I remembered them.....
.
https://www.youtube.com/watch?v=6lfxMfhA3rA


I've just had a look at my own portable generator, albeit a little newer than the enfield would be, it's got a 950w A/C outlet as well as a 12 volt and the engine is only rated at about 6hp.
 
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