Willans Blast Injection engine

[Rustkolector]

Gunna,
I am curious, in the air blast diesel, do you know at what point in the compression stroke the fuel and air blast is introduced to the cylinder? It would seem that it would have to be quite early.

Jeff

 

[gunna]

Hi Jeff, to the best of my (limited) knowledge, it is at tdc or even very slightly later. The temperature in the cylinder at this point is plenty high enough to cause immediate combustion. I must remember when we reassemble this beast to check things like that and make notes of real timings.
Ian.

 

[skyline1]

Hi Fellas

This is a great thread,one guy building a model of a slightly unusual engine and another rebuilding a similar one in full size. Swapping ideas like this is what this site is all about I am following both threads with great interest.

Ian, I didn't realise just how enormous your engine was until I saw the pictures of the valves and you standing on one of the cylinder heads. The diameter of the valves is bigger than the pistons of most motor cars (and a few trucks) and the valve springs are bigger than most suspension springs.

Regards Mark

 

[MuellerNick]

This is a great thread,one guy building a model of a slightly unusual engine and another rebuilding a similar one in full size. Swapping ideas like this is what this site is all about I am following both threads with great interest.

Yes, I have great luck that there is someone working on a similar engine at full size.
Imagine that without the internet.

But the MAN and the Willans and Fairbanks and ... were not at all "slightly unusual". They were a revolution! They brought electricity to almost everywhere without the need of big installations needed for steam engines. The DM-series was the breakthrough for MAN and all licensed designs around the world.
For any Diesel fan, I just can recommend Lyle Cummin's book "Diesel's Engine". He made an incredible effort to trace the history.

Nick

 

[gunna]

Hi Mark, we are only just coming to grips with the size of this thing, as it was shipped to us in pieces from where it had been in storage for a long time. Talk about a giant jigsaw puzzle. We still have some items which are in the "we will find out where that goes when we put it all together" category!

Nick, I can only agree with you about that book, just an incredible piece of work, and very expensive in Oz!

Ian.

 

[skyline1]

Hi Nick

I quite agree about them being a revolution and a compact power source, well compact by comparison to a reciprocating steam plant of similar power output (no boiler for a start).

By unusual I meant unusual to model there being no commercial castings or anything available or drawings for that matter. you have had to do everything from the ground up.

Ian,

Best of luck with your 3D jigsaw puzzle I'd love to do one but it sure wouldn't fit on my coffee table !

 

[gunna]

I couldn't let this slip by. We pulled an injector and dismantled it again, no big deal really as it was only loosely assembled. Anyway here are all the bits with the 300mm ruler down front,

The strange colouring that looks like rust is actually grease. The only part not visible here is the nozzle at the end of the injector. Unlike modern injectors, this one has a hole about 2.5 - 3mm in diameter! The needle seats just before the nozzle, about 10mm up. All the parts here are sitting in the approximate positions they occupy when assembled. The atomiser is a strange beast.

A hollow bronze tube with a stack of plates and spacers fitted to the end and held on by the conical end. The needle passes right through and seats just past the cone. The injector body is bored 35mm diameter to match the discs, and has a taper at the lower end to match the atomiser's tapered cone. The injector body is full of fuel up to the top of the atomiser. All fuel and air then has to pass through the rows of holes when the needle valve opens. Notice that the rows alternate between the outer and inner diameters so making a convoluted path designed to produce lots of turbulance, there could be up to 900psi here. The tapered 'nose-cone' then directs the fuel-air mixture straight towards the open needle valve.

Ian.

 

[gunna]

This engine was taken out of service in the 1960's after a big end failed. As a result, the crankshaft needs some attention. Surprising as it may seem, there is only one company in Oz we could locate that has the capability to regrind a crank of this size. (2.5 metres long, 2.5 tonnes weight). They said they could handle a 1200mm throw, which they can if a modern crank is considered, like this one they had in shop.

Notice the nicely rounded crank webs which take up almost no extra room. However, old cranks are made a little differently.

This is ours with the big square ends on the webs. The area marked in red will have to be cut off both sides of all six webs and then it will fit within their 1200mm window of operations. So now we are looking for someone with a very large mill or some other cutting device to do a bit of surgery.

Ian.

 

[MuellerNick]

So now we are looking for someone with a very large mill or some other cutting device to do a bit of surgery.

Nonono! You can't mill that off!

Aks in the marine engine service department. They do grind pins bigger than yours in situ.
But I have no names and manufacturers.


Nick

 

[crankshafter]

Gunna.
Search for "Goltens", they do insitu crankshaft grinding. They have servicestations all over the world.
Cs

 

[gunna]

Gunna.
Search for "Goltens", they do insitu crankshaft grinding. They have servicestations all over the world.
Cs

Hi crankshafter, as far as I know, the nearest one is in Singapore. Freight costs make that a non-starter for us.

Nick, this is not a spur-of-the-moment decision, the person in charge of this project has worked on this type/size of engine for the last 50 years and I trust his judgement in everything. He says it can be done and if we can find a suitable workshop, it will be done. If we don't resolve this problem then we are just building a static display model.

Ian.

 

[MuellerNick]

He says it can be done and if we can find a suitable workshop

Sure it can be done. Even with a O/A torch.

But I think shipping the crank shaft to two places and the work might not be much cheaper than doing the grinding in place. Those grinders are constructed to be mobile, should not be much bigger than a pallet I guess.


Nick

 

[crankshafter]

Sure it can be done. Even with a O/A torch.

But I think shipping the crank shaft to two places and the work might not be much cheaper than doing the grinding in place. Those grinders are constructed to be mobile, should not be much bigger than a pallet I guess.


Nick

Hi MullerNick/Gunna
Insitu crankgrinding will cost you plenty$$, I know because, we have had insitu grinding of crankshafts on shipengines several times and it cost us so it hurts*knuppel2*
PS my be it's only here in Norway but I doubt it
CS

 

[wheelwright]

I own and operate a commercial machine shop specializing in heavy engines, also restore old engines as a hobby. it would be a real shame to hack lumps off the original crank, plus there is the unknown quantity of how much the crank would be affected. In this case my first reaction would be to polish the crankpin back to clean metal to determine how bad the pin actually is. Based on the photo (which admittedly is not a close up) the pin does not look too bad. In many cases, it looks worse than it is due to melted babbit adhering to the pin. When this is polished off, it will look a lot better. When the pin is cleaned you can assess the actual wear and damage to the pin. If there is only slight scoring and ovality, a lot of this can be polished and stoned out using water or oil stones. Remember that the engine will probably never be run under the original design load, and also will never run the hours it has already run. In general if you can restore up to 70% of the original bearing surface, it will work fine. I know this is not ideal, but it will be infinitely better than chopping lumps off the crank. I have hand polished similar sized crankpins in the past which have gone on to run for thousands of hours. The actual finished size after polishing is not critical as you have to make the bearing fit anyway. Try it, you have nothing to lose and everything to gain, it will cost next to nothing, and with care and constant measuring, it will work. more than happy to offer practical assistance if required. Wheelwright.

 

[Mark Rand]

Can you get the journals turned (and polished, if necessary)? I would be very surprised if the originals were ground.

 

[gunna]

.......Based on the photo (which admittedly is not a close up) the pin does not look too bad. In many cases, it looks worse than it is due to melted babbit adhering to the pin.........

I agree with all your sentiments, wheelwright, but that is not the pin in question. That one was just standing up, posing for a photo. The damaged one has had considerable metal to metal contact and has quite a grooved pattern on it although I could not give a figure for depth. Everything to do with the crank is on hold at the moment while we go through all the possibilities, the main problem being $$$.
It looks like we might go on with the base and flywheel for now, a couple of heavyweights if ever there was.

Nick, I could show some generator pics, but since ours is completely different to yours, and you are doing an excellent job anyway;D, I don't think the dreadful mess ours is in would be of any value.
Ian.

 

[gunna]

I see Nick is making the support arms for the service platform. Here are some of ours, a different pattern to his. There are six in all about 900mm long, each one almost too heavy for one person to lift.

We also went and stood up the three cylinders in their positions relative to each other, so we could start sorting out the pile of copper piping that, as I said earlier, was all supplied to us as loose pieces. You can also see the triangular mounts for the support arms.

Each cylinder has a three-port drip lubricator, of which two ports feed a mechanical pump down on the right hand side. The pump is operated by a secondary connecting rod hanging from the piston skirt. This pump then supplies pressure oil to the cylinder and the gudgeon pin. The third port, to be connected by the twisted bit of tube currently placed behind the lubricator in this photo, just snakes down around the left hand side of the cylinder and drips into a slinger ring on the big-end journal. The four-port splitter up the top of number two cylinder is the blast air supply to the injectors, in at the bottom and three outlets.
Ian.
PS. Crankshaft still under discussion, we may have found another shop able to lathe turn the journals. Should know before Christmas break.

 

[MuellerNick]

Thanks, I love to see these pictures!

I see, that just behind the support arms, you have part of the platform's fence. Or maybe it isn't from this engine. Anyhow, the fence posts, are they cast? Or are they made out of tube and the balls screwd on?


Nick

 

[gunna]

Thanks, I love to see these pictures!
I see, that just behind the support arms, you have part of the platform's fence. Or maybe it isn't from this engine.
Nick

Right the second time, that is just a fence made from steel pipe and mesh to keep small children and their fathers away from the moving bits! I will get some pictures of the platform posts soon when we drag them out of 'storage' round the back of the shed. We are currently dressing up the bed-plate and I will show that soon as well.
The other grey item in that first picture is the outboard bearing from the exciter, if you look closely you can almost see the brush assembly just behind the supports. The cream coloured alternator is from another engine.
Ian.

 

[MuellerNick]

Ian, I do have a question re the flywheel.

It certainly has teeth (pointing inward) to ratchet the crank in starting position. My question is:
Are these teeth cast or machined?
I see no clear evidence for both on my pictures. Casting them sure would be good enough, but on my flywheel, there is a recess behind the teeth that suggests machining (on a slotter).


TIA,
Nick