Lucas C40 22/25amp Dynamos NEW USE

[blodger]

I am amazed at the lack of knowledge the experts have

 

Th field dresistodr is 68 ohms and the ffeld coils 6 ohms unless you have a through bolt short when its 3 .( and that burns out the regulator )

To ploarise link the F terminal to the live on your system so for neg earth thats + to F and Neg to casing.

The cut out is there to disconnect the dynamo from the battery when dynamo output falls below battery volts ...I can tell you how to set it but you need a special ammeter and a voltmeter.

 

 

The two bobin regulators are Compensated regulators ..a turn of fwire carrying current output is wrapped around the voltage regulator so as current rises the output drops...also a turn of wire to drop the output when you put the headlights on ..hence the A and A1.....Dynamos unlike alternators will supply more than the rated current and burn themselves out ...dont exceed 22A

 

The three bobin RB340 has a cutout ,a voltage regulator set at 14.7-15.3 (set at top end) and a current regulator set at 22A ( whilst volt reg is held closed with a crock clip) The three bobin has a resistor across the volt /current reg contacts as well as across the field winding.

 

You can build an electronic regulator quite easily ..there was one in Pratical Electronics in the early 70s .

 

Maax rpm is 9000 rpm

 

You can also make 24v quite easily just drive two dynamos on the same chassis and make one pos earth and one neg earth ...you get your 24v across the two B Terminals on the two regulators..one is + and one -

 

If you need any help just let me know ......hope you like the new avatar ....

It seems that a lot of knowledge has been lost but as I have discovered dynamos still have a use and are ideal as a battery charger married to a suffolk punch engine.

I have gone for doing it unregulated so that you watch the amps & volts for the short running periods. A diode switched in at start up, then out, with a couple of 25watt 2.2 ohm resistors to switch out of the field circuit for a slow start seems to work fine. I also have a 90 ohm resistor across the switch that connects the field replicating the 68 ohm (quenching)regulator one.

The dynamo has never worked on my sister's 25/30 year old Zetor tractor so I have put the knowledge gained on here to good use in replacing it and coupling it to the mentioned RB340 while I try to disentangle/remove the existing wiring and czech control box.

It all came about because I put a 99p bid on some untested dynamos on Ebay and won and had to collect!

 

I do not know what function avatars have other than to portray or convey something about the person to whom they are attached. Most seem to go for something comical or striking. Your last had people looking twice. I have not got round to working out how to do one yet to slow the download down for those on mobile dongles.

[pistnbroke]

your tractor may havea sealed dynamo ...no fan ..rated at 12 A just for the lights ....RB 106 control box or you can use a RB340 if you set the current reg for 12A

 

Avatars oh yes the moderator did not like the two rocks and the trees ..had had complaints ..perhaps he prefers the man with the big cock he did not like the girl with here nickers down to her knees either !!!

 

if you need help with the dynamos just let me know ..all the old knowledge is in my head ..

[OptedOut]

Electrics are not my area but if you intend to go down the resistor road I suspect you will need one of these, possibly with a higher ohms range.

[pistnbroke]

In the old language a RHEOSTAT thats a variable resistor today ...best put an RB 340 on it

[blodger]

your tractor may havea sealed dynamo ...no fan ..rated at 12 A just for the lights ....RB 106 control box or you can use a RB340 if you set the current reg for 12A

 

Avatars oh yes the moderator did not like the two rocks and the trees ..had had complaints ..perhaps he prefers the man with the big cock he did not like the girl with here nickers down to her knees either !!!

 

if you need help with the dynamos just let me know ..all the old knowledge is in my head ..

 

The chzech dynamo has stud and nut connections for field and D or B. I removed the pulley which has the fan cast in the back of it and managed to fit it to a C40. The dynamo motors slowly when positive is applied to the field and stalls when D is also connected. I am waiting for a workshop manual on CD before I investigate further. The brushes are not mounted 180 deg to each other but seem to be at 90 deg. I am waiting for WD40 to work to get to remove the old control box as its not worth the effort of drilling out the set screws to get the cowling off for access.

[blodger]

Just an update for anybody interested,

 

The tractor reg, having extricated it, is a three bobbin type with three connections. B Battery, D/61 Field & M presumably equivalent to A or A1 to ammeter.

 

The M connection appears to be a direct short to Earth/reg body.

 

I have run the dynamo via a lawnmower engine and applied batt volts to the field, D/61, and the output at M, the other terminal, is just the batt volts which declines with time.

 

The inside of the reg is pristine and no signs of damage or heat, likewise the dynamo.

 

I have concluded that the reg went awol the M connection shorted to earth meant the dynamo was maxing out and has burnt out some of the dynamo stator windings. The rest of the reg has continued to work in that had it connected the battery to the dynamo then it would have shorted the battery as well and it did not.

 

The C40 & RB340 seem to be doing the job and I have got it going through the amp meter. I have also fitted an alternative charge warning light which from what I understand is a bit more duplicious than an alt one, possibly more misleading.

 

So I am consigning the original dynamo and reg to the recycling scrap heap unless someone can point out that I have gone wrong somewhere, etc

[pistnbroke]

Just an update for anybody interested,

 

The tractor reg, having extricated it, is a three bobbin type with three connections. B Battery, D/61 Field & M presumably equivalent to A or A1 to ammeter.

 

B is battery three bobin regulators do not have A A1 or equivalent thats for compensated regulaters.

D and F normal Warning light goes from D to bulb to ignition Goes out when cut out closes.Let me know the regulator number and I will sort out the M for you. All regulators must have an earth

 

The M connection appears to be a direct short to Earth/reg body.

 

I have run the dynamo via a lawnmower engine and applied batt volts to the field, D/61, and the output at M, the other terminal, is just the batt volts which declines with time.

 

To test your dynamo join F and D if OK voltage will rise fast to way over charging voltage....voltmeter D to earth...0-100v scale

 

The inside of the reg is pristine and no signs of damage or heat, likewise the dynamo.

 

I have concluded that the reg went awol the M connection shorted to earth meant the dynamo was maxing out and has burnt out some of the dynamo stator windings. The rest of the reg has continued to work in that had it connected the battery to the dynamo then it would have shorted the battery as well and it did not.

 

A dynamo has an Armature not Rotor and Field coils not stator

The C40 & RB340 seem to be doing the job and I have got it going through the amp meter. I have also fitted an alternative charge warning light which from what I understand is a bit more duplicious than an alt one, possibly more misleading.

 

So I am consigning the original dynamo and reg to the recycling scrap heap unless someone can point out that I have gone wrong somewhere, etc

[Sir Nibble]

Really really sorry to "bump" this but I thought it would be useful for you to know that the tests you did on the Czech dynamo suggest it is quite healthy but wired for negative regulation. That means that it works when a -ve is supplied to the DF terminal unlike the Lucas which uses a +ve. You need a reg from a VW beetle or suchlike and it will work fine.

As an aside, dynamos are most definately unidirectional and won't work if spun the wrong way until the field connections are swapped internally. Mr Fleming's right hand gets in a twist.

[Gibbo]

As an aside, dynamos are most definately unidirectional and won't work if spun the wrong way until the field connections are swapped internally. Mr Fleming's right hand gets in a twist.

 

Can you clarify on this because theory says it will make no difference, my old Lucas manual says it makes no difference and I tried one and it made no difference.

 

Are there some type with offset brushes or something?

[Sir Nibble]

Can you clarify on this because theory says it will make no difference, my old Lucas manual says it makes no difference and I tried one and it made no difference.

 

Are there some type with offset brushes or something?

Yes I can clarify it, nothing to do with offset brushes Flemings right hand rule says it can't be done unless you have an insulated dynamo with F+ and F- terminals. Gen spins, V appears on +ve brush and feeds F, field grows and cut in closes. Now, spin it the wrong way and the wrong polarity appears at the brushes which reverses the feild polarity, hurrah! we will now get the correct output! No, because that now re-reverses the field and you're back to square one, the machine is effectively stalled with any armature output immediately fed the wrong way through the field to kill it dead. Try it with your right hand (ooer missus) and you will find your wrist will get a good flexing.

I once encountered this in a mammoth head scratching session over a flat tank Norton which rejected it's replacement dynamo.

[Gibbo]

Yes I can clarify it, nothing to do with offset brushes Flemings right hand rule says it can't be done unless you have an insulated dynamo with F+ and F- terminals. Gen spins, V appears on +ve brush and feeds F, field grows and cut in closes. Now, spin it the wrong way and the wrong polarity appears at the brushes which reverses the feild polarity, hurrah! we will now get the correct output! No, because that now re-reverses the field and you're back to square one, the machine is effectively stalled with any armature output immediately fed the wrong way through the field to kill it dead. Try it with your right hand (ooer missus) and you will find your wrist will get a good flexing.

I once encountered this in a mammoth head scratching session over a flat tank Norton which rejected it's replacement dynamo.

 

Aye. I see what you mean. I shall now go and have to dig out that dynamo again, have a play and work out why it worked fine in both directions. I wonder if I have an oddball design dynamo? Are you aware of any? I also have an old Lucas manual which says it works both ways but I didn't look what model/s it was for. I'll try to scan it.

[blodger]

Really really sorry to "bump" this but I thought it would be useful for you to know that the tests you did on the Czech dynamo suggest it is quite healthy but wired for negative regulation. That means that it works when a -ve is supplied to the DF terminal unlike the Lucas which uses a +ve. You need a reg from a VW beetle or suchlike and it will work fine.

As an aside, dynamos are most definately unidirectional and won't work if spun the wrong way until the field connections are swapped internally. Mr Fleming's right hand gets in a twist.

I wondered whether at some point the batts had been re-connected wrong so I did try running (off the tractor) the Czech dynamo positive earthed with no better results. It is now stored alongside the tractor should the C40/RB340 I have fitted fail. I understand the charge light is working and that the ammeter wobbles about on the right side when the tractor is used. They have not had to take the batts off to charge them since.

Thanks for your thoughts/experience

[blodger]

Aye. I see what you mean. I shall now go and have to dig out that dynamo again, have a play and work out why it worked fine in both directions. I wonder if I have an oddball design dynamo? Are you aware of any? I also have an old Lucas manual which says it works both ways but I didn't look what model/s it was for. I'll try to scan it.

Some posts back I said I had had a leaflet that advised, to get the dynamo to work in reverse, unsoldering and reversing the internal connections on the F spade one of which goes to earth through the pop rivet connecting it through the spade insulator, the other insulated by the latter. These connections appear to be the ends of the pair of the stator coils with the other wire from each twisted and soldered together.

I have got round to doing this and indeed it motors in reverse.

I am only doing so to make a more compact dynamo lawnmower generator that gives 20 amps or 20ah for a tank of petrol.

I have found that the Suffolk engines give more with a dynamo than with an alternator.

The next thing is to improve the silencing.