OneGuyFromBarlick

Yes, but in at least one way mine is better because the crankshaft will be mounted on two bearings. I never liked disc cranks and overhung flywheels on a single bearing. Many got away with this by having an outrigger frame with another bearing on to support the outboard end of the flyshaft. On old donkey's like the one at Bancroft the crank pin on the disc wore very quickly. It's a trade off of course.....

The donkey in the tape room at Bancroft Shed had an outrigger stand to support the massive belt drive to the shafting for use when the main engine was stopped.

Hot Neck (I never knew his proper name) and Jim Fort repairing a bearing on the tape drive countershaft at Bancroft Shed shortly before we closed down.

The Bancroft donkey engine survived because Robert Aram bought it. I think it lives at Masson Mill these days.....

The East Hill donkey engine is still growing!

Have a look at Shed Matters for some information about lubrication and bearings on steam engines. I'm not going to repeat it here.

One thing you soon learn if you are tenting an old engine is to refrain from tightening loose bearing caps. They are often loose for a reason! The Low Pressure side pillow bearing for the flyshaft at Bancroft is a good example. The cap nuts are only finger tight. If you screw them down a fraction with your fingers before starting you will be stopped with a hot bearing within 30 minutes. It's a manufacturing fault. Whoever bored the housing omitted to raise the boring bar a fraction and take a light cut out of the cap. The consequence is that if tightened down at all the pressure on the shaft is high enough to generate heat and stop you. What it needed was a couple of spacers under the cap but like all the previous tenters I never got round to it, no need for it as long as you left it alone....

Stanley,
These oilers fascinate me, I can watch them for hours but what keeps the banjo (?) in its position? Why doesn't it follow a much greater arc? Is it a matter of geometry, that the centre of the banjo is in the same plane as the centre of the bearing?

db

You've got it. The centre of the banjo is on the centre line of the shaft so though rotating it stays in the same plane and position. Once the oil has dropped in it is moved by centrifugal force along the pipe into the crank brass. I always started the drip feed lubricators 15 minutes before starting the engine so all the bearings had a good initial charge of oil.

Thanks for that.
db

Another advantage of the banjo oiler was that if there was a temporary stoppage in the drip feed lubricator supplying it you could pour a dose of oil directly into the banjo as it was turning to give you some respite while you cured the problem. Usually just a bit of dirt or thread in the drip control valve.

That reminds me of one of the rules of engine tenting. Walk round the engine and check on things, particularly oil feeds, every ten minutes or so. Mind you, if you were doing this on autopilot you could sometimes slip up! More than once I have turned off the oil feeds on one of the pedestal bearings because I wasn't thinking and my head had gone into shut-down mode! As it happened this was not a problem as long as your oil levels were well up and the pumps in good condition as the overflow after shutting the cocks off went through the bearings and protected them. A good design that was fail safe. One of the first things I did when I took over the engine was to clean all the oil gutters out, check the rope drives to the pumps and the pumps themselves. A well maintained pump had a bigger capacity to pump than the quantity of oil going through the bearing so in practice, if you had everything right, the oil was always overflowing even if all the cocks were open.

My mind is still on lubrication. One thing that strikes me after many years working with engines and researching their history is that lubrication was seen as not worthy of interest apart from regularly popping something into a bearing that helped it to do its job. When Fairbairn wrote his seminal 'Mills and Millwork' he devoted only a couple of paragraphs to lubrication. For years before the first oil wells were drilled and mineral oil became available in quantity, lubrication was on the level of poring the bacon fat from the frying pan into a bearing. Tallow, castor oil and other vegetable oils were all that was available. It was only when duties increased and people were looking for ways of selling mineral oils that things began to change. The modern science of tribology is fairly recent (the study of friction, lubrication and wear). I once talked to a man at Sheffield who sat on the committee that decided the name and the pronunciation, he told me they decided on the phonetic equivalent of 'try' for the first syllable.
The old engineers recognised thick and thin oils and on slow bearing surfaces advocated grease. It was very hit and miss. On steam engines cylinder oils were a good example of the evolution of a correct lubricant, in the beginning it was high melting point that mattered and tallow was the favourite. The introduction of superheat on engines forced a rethink as the old oils were useless. Many engines were more efficient on superheat but wore their cylinders out. Gradually oils were developed that were soluble in steam and reached all parts but when they cooled became a protective film on internal surfaces. We have come a long way since Tallow and Castor Oil were the mainstays.....

Have a look at these posts of a whim in Australia,
http://www.practicalmachinist.com/vb/an ... im-299994/

Lots of Cornish hard rock miners finished up there Bodge and they took the technology with them.

The beam on one of the big pumping engines at Kew Bridge. Engines like this were exported abroad particularly by Harvey's at Hayle. Look for Gwalia on the site search.....

The East hill donkey progresses... See Shed Matters....

My latest flywheel is solid as were many on early, smaller steam engines. However, look carefully at the bigger, later engines and you will find that the flywheels built up out of individual castings (Ellenroad is 85 tons) are very complicated and a wonder of cast iron technology. I doubt if we could make these today as the technique of allowing for shrinkage in very large this castings has largely been lost. The last time I saw it was at Tatham's in Rochdale who were casting large cast iron carding engine cylinders. Very thin walls and they had to be perfectly concentric and balances. I think they are out of business now....

My solid flywheel.



The last rim segment going on to the Whitelees wheel. The gear segments followed to complete it. All beautifully made and wedged together. It ran true when we completed it.

The flywheel of the Jubilee engine as installed at Masson was built on exactly the same principle but on a more massive scale. It too fitted together perfectly, a tribute to the skill of the original engineers and fitters.

One thing that always struck me when working on old engines was the way the fitters only applied high levels of finish where it was needed. The cuts taken on the lathe and the planer were very coarse but regular. One trick they used regularly when planing surfaces that needed to be finished accurately by scraping was to take out the middle third of the surface with a gutter. This cut down on the amount of finishing and didn't affect the strength of the fit. When they needed a polished finish it was usually handed over to the apprentices and labourers and they did the donkey work.

The massive crank on the Ellenroad engine. Ever wondered how they cut this to shape on the outside? No flame cutting in those days....

The answer is that when thy bored it for the crank and the shaft they turned the faces smooth but then put it on a big slotting machine to carve the profile. Than over to the apprentices and labourers, plenty of elbow grease and britches arse steam! That's how you got polished cranks.....