WW2 US Army Homelite Generating Set

Right, suppose I should write a little about this project. My brother & me bought this engine many years ago, we took it apart a bit, but had so many other projects on the go it kind of always got put to the back & forgotten. When the family home got sold & the engines went into storage I put the main lump back together. There are, however, many smaller bits to contend with, as it's a very complicated engine. I'm not sure which bits have survived the various moves, I know for a fact the sprung mounting skids have disappeared, I think I've still got the carb bits somewhere but I'm not sure about the fuel tank, & the fuel tank is very important with this one, for reasons which will become evident soon.

Anyway, off we went to my sister's garden on Sunday, to grab a couple more engines off the pile. Things have grown a bit since we were last there (picking up the Tarpen), we had to chop our way through, bue eventually came upon the engine pile, covered with a tarp.....



We dug around & I found what I was looking for, looking very sorry, but the flywheel turned, which was a bonus. Can you make it out?....



So, out she came, cleared some of the mud & dead leaves off her, ready to load into Ian's car....



Got her home & immediately started work. I wanted to separate engine from generator, which took some doing, but eventually it came apart....



Got the head, barrel & piston off, then I looked inside the crank case & realised there were springs & stuff inside the crank webs. I remember seeing them years ago, but had never given it much thought, so I got the engine (bottom half, minus barrel, piston etc) in the vice & set about trying to undo the flywheel, to get at the mag & hopefully get inside the engine.

I got the flywheel bolt undone & used a puller to get the flywheel off, I had to be careful here as it's aluminium & I definitley don't want to break this one! If the starter dog had been on there it would've acted as it's own puller, but this is with the carb bits, somewhere. Anyway, into the mag....



There's a stamp which says "Moisture and fungus treated Nov 1944" so it should be fine then




Continued in next post.....

Good luck with this one, hope you can do a good job on this as you did with the tarpen.

Stu.

So I got the mag back plate off, released the screws holding the front onto the crank case (I wouldn't exactly call it splitting the crank cases, it's more of a manifold, or just the front of the crank case, this is a complicated, very well engineered little engine) & I expected the shaft to stay there while I pulled this part off, but the shaft came with it, as did one of the crank webs, leaving the con rod, other crank web & rest of the shaft inside the rest of the crank case....

Here's it with the mag plate off, leaving the manifold thingy, screws now out....



Here's what was left after I removed it.....



& here's the bit that came off....



This bit is actually a disc valve assembly, you see this engine has the fuel tank underneath, & the carb sucks fuel up, with a little help from crank case pressure. There's loads of little pipes all over the place, when it's complete, & the tank has more little pipes built into it, which is why I'm hoping it's still around.

This disc valve also contains a centrifugal throttle assembly, so there's no way to alter the speed of the engine as it's set by the spring on this throttle plate (which is the spring I could see when I looked down into the crank case earlier)

I managed to get this lot apart, so I could take some pictures. Here's the manifold which is also the end of the crank case, the carb bolts onto the hole on the right, the crank shaft goes through the hole in the middle, the other, weird shaped hole is where the mixture enters the crank case (this is with the disc valve removed)....



The disc valve runs metal to metal against the above piece, relying on a film of oil to keep it lubricated. It presses against it with spring pressure. The back of this disc valve looks like this (remember, whilst running, this piece will be spinning around, the above piece stays still)....



& here's the front of it (same piece as above), with the crank web removed so you can see the centrifugal throttle plate....



It gets more complicated than this though, if I go back to this picture you'll see a small hole at the bottom of the circle....



This feeds a tiny little pipe union, which I think goes back into the fuel tank, maybe creating pressure in there or something, but it is uncovered by the throttle slide at the correct time of the cycle, for whatever reason.

It's a highly over complicated, over engineered piece of kit, especially for war time, but I've researched it & they were supposed to be a very robust engine, apparently going on for ever, but spares are practically unheard of!

The big end has split caged rollers....



The little end has a double row of needle rollers....



The barrel is a lovely piece of die-cast aluminium, with a shrunken steel liner, light as a feather & heavily ported....



But with all those ports in the barrel, it's strange to find no pegs in the piston ring grooves, the ports must be engineered so that they are too small for a ring to jump out if the gap moves round. The piston itself is a work of art, beautifully cast & extremely light....



Anyway, I think that's about it for now, next job is to try & get the generator apart. I've also got to get down my sister's place & see what other parts I can find, as this project now hangs on what I still have. I think if the tank's missing it might be a no-go'er, although it could be made to run with a normal carb, modified to fit & a different tank mounted above. We'll have to wait & see.

I see what you mean by saying it's well engineered or even over engineered, it sure is a fantastic engine that should last for years as it seems to have everything well thought out. I hope you still have the tank and it's useable, even that side of the engine is very well thought out but I wonder if all the small pipes would have caused problems out in the field.

Stu.

I wondered that, but they seem to be very highly regarded in the states.

I'm not going to get a chance to look for that tank now until next week, so fingers crossed.

I'm off to the Ringmer Steam & Country Show this weekend, not taking an engine (well, haven't got one entered, might see if they'll take the Tarpen, but looks doubtful) I'm taking my car, my dad's taking his bike, & my brother's paid for his camping & show entry.

well nuts..
looks like your getting on with this one well
good luck with it...its nice to see them come back to life after being abandoned for so long...
mike.......

That looks in remarkable condition for something that's been standing outside for some time. With regards to the tank, most Briggs & Stratton small engines use a suction feed system so it may be that a tank from one of those can be adapted to suit.

It looks to me like you really have the bug.
I thought the Tarpan project was interesting because it was different - same with this one.

Regards Graeme

Seems a little strange to have 2 condensors inside that mag, looks to me like someone had an issue and added one... Still, at least you have a spare

It's an interesting piece of kit actually, be good to see it running someday.

Paul

pauldg wrote:Seems a little strange to have 2 condensors inside that mag, looks to me like someone had an issue and added one... Still, at least you have a spare

It's an interesting piece of kit actually, be good to see it running someday.

Paul

I thought that & had a careful look at it, it looks to me like it was meant to be like that. I think it's got something to do with suppression of radio interference, especially as there's another few condensers on the back of the genny as well.

This model in particular was used for radar & radio communications equipment, & I'm told it was a relatively front line engine, as it has a very effective silencer (still don't know if I've got that either). I've tested both those condensers on my LC meter (inductance & capacitance test meter) & they both seem to be reading about the same.

I don't think this engine saw much action, is was made in November 1944 & did have 2 service stamps on a little plate (which has since disintegrated in the soil) My guess is it was made in the US, shipped over, but never actually made it across the channel. I bet there's a few sitting over in Germany & France.

I would've thought a screened HT lead would be a more effective suppression measure for the ignition than multiple condensors given what they actually do... They also look a bit 'off' with the orientation etc. but I haven't seen them in the same detail as you can.

It has a screened HT lead as well. I thought the 2nd condenser (the one furthest away from the stop button) was a later addition, as the holes just looked like they were tapped into the base plate, but when I turned the base plate over there is actually a little extra bit on the casting for these holes.

If I get a chance I'll take some pics of it, see what you think. This whole engine is turning out to be a bit of a mystery It's always good to get a few more opinions & insights.

OK, so I got the mag out for another look (I've already cleaned it all up, re-surfaced the points & reassembled it) it seems I was getting a bit mixed up earlier with the condensers & which one was which.

So, here's a pic of both, in the complete mag, with coil at the top & stop button near the bottom...



Close-up on the condensers, still roughly in the same orientation...



Now, I'll start with the condenser nearest to the stop switch (the one which the stop switch actually acts upon), from the inside it looks like it's a bit of an afterthought....



But from the back you can see it's clearly meant to be there....



Now to the other condenser. From inside it looks like that's exactly where it's meant to be....



But from the back it's a different story, now this one looks like an afterthought....



So I dunno, personally I think they're both meant to be there, but I don't know why. Possibly because condensers weren't all that reliable back then, so maybe fitting 2 was some kind of fail-safe. But when you wire 2 capacitors in parallel like this you're actually adding their capacitance (their value) together, so it's like having one big capacitor (a condenser is just a capacitor). It can't be meant to deal with higher voltages (like an extra high power mag coil or something) because in parallel you keep the same voltage rating, you only add extra voltage capacity in capacitors by wiring in series.

Anyway, here's another pic, hopefully to make it a bit clearer. Here's a pic of the mag with the condensers out, showing the proximity of the holes, the only thing going against the second condenser is that the holes are very close to the centre of the mag, but there's plenty of casting & where the holes are tapped looks to me like a little shelf to mount a condenser on....



Well I expect I've bored you all enough with all this techy talk for now. I got this engine with 2 condensers on it, so I will just leave them there. When the day comes that they need replacing I will just replace them both with one modern one (usually a pattern part Lucas one, off a Mini).

Could it be something to do with the high revs this engine was designed to do?

I really don't understand the black art of magnetos so it is just a guess, I'm more of a carburettor man myself

Why have you got the symbol for Caduceus for your avatar Ian???

Yeah I suppose it could be something to do with that, but I'm not sure. Think I may have to put my first post on SmokeSatck over the weekend (if I get any internet signal on my phone, & if my caravan battery stops playing silly buggers)

A few observations, whether they are correct or not can be decided later

Does the stop button tang actually contact the wire terminal or the threaded end of the condensor? Looks from the angle that it'll miss and hit the case or the insulating washer (if there is one).

Like you say, 2 capacitors in parallel adds the capacitance. This would surely reduce the 'sharpness' of the voltage spike on the LT side of the coil and actually reduce the efficiency of the coil and the strength of the spark. If the 'angle' of the back emf is too shallow the voltage induced on the HT side will be lower.

I don't think it would be a speed thing, most condensors are about the same value. If one on a V8 car engine copes with 200 operations a second (at 3000rpm) then this engine would have to be screaming away at 12000rpm to equal that. Even then, you wouldn't be reaching the physical limits of the condensor.

It'd be interesting to see what difference there is running with both and with a single one, just to see what happens.

nutgone wrote:Why have you got the symbol for Caduceus for your avatar Ian???

It's the Venom arms logo. Anybody who knows anything about air rifles would know that

pauldg wrote:

It'd be interesting to see what difference there is running with both and with a single one, just to see what happens.

It'll be interesting to see it running full stop!

The stop switch actually hits a brass washer on top of the condenser which is part of the hot side, they're built a little differently these old ones, I will have to get pretty creative if they ever need replacing.

Well I wonder if it's as simple as these two condensers simply add up to the value of a normal condenser. I've forgotten what the value of the pair of them was now, will have to get my tester out again when I get back from the rally this weekend. I know these old Wico mags have quite a large points gap (.020") but I always thought that was more to do with the dwell angle.

If it needs replacing, just get one for a wipac 'CJ', cut down the threaded bolt to the right length and then desolder the mounting tab from the old one and solder it on the new one. Or you could always just get any old cap of around the right value and stick that in the case of the old one instead.

The points gap shouldn't affect what capacitance it needs...

Either way, if it sparks well enough it's not really an issue

Yesterday I decided to take out some pent-up aggression on this thing, there's a few stubborn bolts I've been meaning to get undone. Firstly I wanted to get the generator apart & get the armature out (which should really be called a Rotor, but let's not get too technical just yet). It's held in by a bearing with 2 locking nuts on the end, but the generator assembly also splits into separate parts, as it produces both AC & DC power, these outer parts should separate, trouble is it's all held together with long screws, with slotted heads, not proper nuts & bolts.

After breaking my 2 largest screw drivers I managed to get 3 of the 4 screws undone, my brother turned up with his impact driver just in time for me to get the other one out, therefore separating the generator into it's different bits. From left to right we have the AC part then the DC parts....



I also managed to get the rotor out, this is a double affair, with the AC rotor on one end & the DC armature on the other. I can only assume the DC armature causes a magnetic field in the AC rotor (which is one of the bits I need some more clarity on), here it is....



The laminations on the rotor have also suffered a bit, as you can see here (I have no idea if it'll ever produce electricity again)....





And the windings on the DC armature look like the shellac (or whatever they used) has melted or something ???



Also, the field windings on the DC side seem to have suffered some degradation to the outer protective covering, it's just rotted in places...



I have no idea about the field windings on the AC side, they look OK, I haven't attempted testing them yet as I have no idea what the configuration is. I know there's 4 wires though...



The DC side has 4 brushes, 2 of which have capacitors connected (I'm assuming for radio interference suppression). Some of these seem to be connected to the AC windings as well, but until I get the old voltage regulator unit back from my sister's place I doubt it'll make a lot of sense (I know I still have this bit at least). The markings on these capacitors are pretty readable, I can get everything except a voltage rating. The capacitance is also marked as MFD, which could be Micro Farads or Milli Farads, either way it's 0.1MFD....



So then I turned my attention to the engine. I've been wanting to get the cooling fan off for ages now, it's got a left-hand thread on it, & nothing to stop the shaft spinning, until now. Now I've got that rotor out I can re-mount that on the end of the crank shaft & use that to stop things turning.

Trouble is that left hand threaded nut is bloody tight! After almost breaking one of my ribs with a pair of Mole Grips, I found the biggest wrench in my dad's tool box & managed to shift the damn thing!

So, off came the nut, but the fan wouldn't budge! I lightly tapped the end of the crank shaft with a copper mallet & something popped out. I picked up what I had.....
Half a crank shaft (the other half I got out ages ago, with the disc valve on it) & the crank case with the fan still attached!

Seems there's some weird arrangement of bushes, bearings & spacers in there, the fan is a press fit in that lot, along with a few different sealed bearings....



I think I may just have to leave it there, as I would probably need to press out the fan assembly. The sealed bearings seem to be ok, although I'm a little worried their grease will have been washed out with all the WD40 & Brake & Clutch Cleaner I've had in there. The generator had a sealed bearing on the end, which I took off to find out it had a hole punctured in the shield. It seems to have leaked most of it's grease out onto the end of the commutator, so I removed the shield on that side & will re-pack it myself with grease on reassembly.

As usual there are more pics on the album...

http://photobucket.com/nutgonesyankgenny

Next step is to find out if I've still got the fuel tank & other bits, otherwise it'll have to be modified to run on a normal carb with gravity feed.

That all looks nice and crunchy You don't need all that metal anyway, most of it is just decoration - plus, just think of the weight savings

If you can get the control box then do up some sort of wiring diagram I can assist with some tests to do - If it's electrically ok then I reckon it'll generate 'something'.

I've been kind of working it through in my head what it all does. Each of the DC field windings has 2 sets of ... err... windings. The thinner enamelled copper wire closer to the core & a much thicker wire outside of that (which I think can be seen in the pics above). Now some of this is connected to the AC field windings, which aren't as visible, so I don't know what's going on in there.
The DC side of these also acted as a starter, so I wonder if this has something to do with the thicker coils on the stator magnets???

I'm guessing that rotor won't be magnetised as such. Is it more used to pass a magnetic flux through it's laminations???

Anyway, I've labelled all the wires up, so I know where they all go. There's also a funny looking thing sticking out of the back which has a wire each end, I'm guessing it's a large wire-wound resistor. This is the only part of the whole thing to have "Homelite" actually written on it.

Back to the mechanicals, I finally got that fan off today. The outer bearing is a sealed-for-life jobby, but has some oily stuff leaking out, I'm guessing from all the WD40, 2 stroke & Brake & Clutch cleaner I've used near it. It seems to be rolling OK though.....



The inner of the bearings looks like a sealed for life one from the inside of the engine, but has "Shield Bearing" stamped on it. The outer face has, or rather "had", a fibre seal over it (first stage crank case seal I guess), this has broken down & I've managed to punch the bearing out. I will have to see what I can do to replace this seal/washer, maybe I can cut one from gasket paper or something.



the 2 bearings had this spacer tightly between them....



As you will see here, the inner "shield" bearing has a groove around it's outer....



There are 2 set screws which go inside the crank case, they have split spring washers on them, which locate in this groove, you can see where they go here....



Dunno what else to say really, I'm glad I got this last bit apart, as there was some crap in there, but I reckon if it had been left undisturbed that felt seal (fibre washer/seal or whatever it is) would've probably been OK, but who's to know.

I reckon I'm going to need a press to get it all back together though. I know where there are a couple of hydraulic presses, but I've kinda lent on their owners quite heavily in the past for favours. It's a tool both my dad & me have wanted for a long time now, & they can be bought brand new for £"not too much" maybe it's time we clubbed together & bought one between us.

This really is it now until I find the missing parts. Unless I decide to have a play with my multimeter & some of the genny wiring....

I know nothing about generators but looking at that you've got your work cut out if that's ever going to produce power again, to me it looks like scrap but I'm sure if anyone can sort it you'll be able to.

Good luck,

Stu.

Well, I'm not too sure about the genny side of things, but I've got a good feeling I can make it do something (with a little help from one or two members here ) but I think that engine main bearing has had it, it's very noisy, probably because I knocked it out by it's centre (very naughty ). I will probably still use it though, as it's got that groove in it & will probably be very difficult, if not impossible, to replace. I'll make up a new seal for it (it's some kind of paper/fibre seal) probably out of gasket paper, unless I can find something more suitable. It's not like it's under immense strain, & the other bearings seem fine anyway.

The bit I'm worried about is reassembly, there's so many different spacers, keys, bearings, screws & nuts & stuff it's difficult to remember what sequence it all goes in.

Where I've got a few different bearings, seals & spacers, in a particular order I've put them all together with either a nut & bolt (with a couple of washers) or a cable tie, to keep it all in the correct order. I've also taken plenty of photos.

This is a very complicated machine, with too many small parts. There's also the question of a press. I might be able to assemble it without one, if I can lay my hands on some brass punches (I'm told they're good for putting bearings in). Still, that's not the end of the world, first I need to find the missing bits at my sister's place. I'm looking after her dogs for her from tomorrow (Saturday) until Wednesday, which should give me time to empty her shed out & see what I can turn up.
(I've got a horrible feeling the tank isn't there )