BR Standard class 6 No. 72010 'Hengist' and Clan Discussion Thread

Yes, but the A1/A3s had frame problems from day two.

 

You already advised this, Sorry std, subject of that post had moved on from chimneys to Cylinder blocks...

 

Are the cylinders going to be cast in steel , with liners fitted, or in SG iron?

 

Sorry No it doesnt.
The example given demonstrates what replacing a Monojet /single chimney with a double Kyllchap might achieve. But since the kind of exhaust system advocated by Mr Koopmans (no splitters, no cowls, no 'mixing chambers etc) has never been fitted to an A4 then this one is unanswered, the nearest example i can think of would be ' Le Maitre' versus Giesl on WC/BB'S and i dont think there was much in it...

 

I generally agree with that but I wonder to what extent there is any assurance that the common CAD packages will continue to be supported (and clearly one would have to take a view of the value of that assurance). I am guessing that the software is proprietary so would not be easily transferrable to another platform. Possibly not quite the same considerations but Adobe pulled the plug on Muse recently upsetting quite a lot of people. I guess it comes down to initial cost of software v. wooden pattern, and if you are able to re-use either, it is a bonus.

 

Some (non-railway) fluid dynamisists that I have spoken to are of the view that a free jet in a smokebox would have significant energy losses due to turbulence etc., and that some surfaces in sensible locations can improve matters. What the best locations are is another question!

 

Some occasional testing is being carried out, subject to the availability of railways and suitable locomotives. Hopefully the answer to the question about transonic velocities will be available in due course.

 

I'll try to find out

 

Until Adobe pulls the plug on PDF and the code is lost for step file translators, I'd say modern engineering data is fairly safe from total obsolescence.

CAD interchange formats tend to endure, as is shown by the refusal of .stl and .dxf to die, but step (.stp) files and parasolids (.x_t) are both pretty good and widely used.

 

I have no ambition to fit a system to an A4, the Kylchap works fine as it is. I am advocating multiple jets for existing chimneys, as a consequence I use the orifice distance proposed by Ell, 6 times the diameter of the orifices. This give a higher blastpipe. Anyone that wants to lower the chimney entrance to that distance from the smokebox bottom is welcome.

These energy losses could only exist if the jet width at the chimney entrance would be larger than the entrance. If it is not, the jet influence cannot spread into the smokebox since all flow affected is entering the chimney. I would like to make the point that such losses do not appear in my revised momentum calculations which are only a few % off the Rugby test results.
Kind regards
Jos

 

The cylinders are being cast in SG iron. I'm told that SG iron flows better than steel. The pattern is being built in line with the contraction rates of SG iron. The liners will be cast iron, diesel quality machined to the original BR drawing.

Ian

 

Jos,
At the end of section 7.6.3 (page 140) of "The fire burns much better..." it says "It is conceivable that a properly designed petticoat could act as a sequential ejector. However this approach does not appear to have been the subject of any investigation."
I can't find anything about sequential ejectors on the internet, is it possible to say some more about this?
Thanks and Regards

 

Since the orifice ejects in the lowest cowl which in turn ejects in the next cowl which finally ejects in the chimney, these cowls could be regarded as an orifice-chimney combination by itself. It is a system in sequence contrary to a double chimney which is parallel.
I used the word in my book since a proper definition was unavailable, you can call it as you like: stepped, staged?? As no data is available on the behaviour of these cowls of which length and diameter are about the same I assumed momentum conservation which gave a result. Whether that is sufficient for a Kylchap calculation remains to be seen.
Kind regards
Jos

 

We are hosting an open day in Sheffield on 27 April. This will be open to non members so if you want to come and see what we're doing you will be very welcome. You can find more details here

https://www.theclanproject.org/Clan_OpenDay.php

 

Quite right it does: the carbon in cast iron imparts fluidity and runs well into the mould but as flakes imparts brittleness to the cooled casting.
Heat treatment & optimising the exact melt that is run in rearrange the carbon into little balls and the result is quite comparable to cast steel but
you do lose the self lubricating properties that the flakes confer - so the cylinder liners are cast but not nodular.

I believe the first time it was used for locomotive cylinders was when on specialist advice it was used for the new outside cylinders on the
Duke of Gloucester's restoration. The technique though is long established - "mallablised", "spheroidal cast" - if usually for much smaller things
e.g. the jointing pieces for the frames of "good value"bicycles like Hercules.

 

Progress this week. Finally the cast steel stretchers are out of the machine shop and are in the assembly area.

https://www.theclanproject.org/Clan_News.php

After the photo was taken the stretchers were lifted onto trolleys ready to be craned into position on the base frame that CTL Seal will use to erect the frames

 

Good to see the progress of this...... after all the tribulations in the past!

 

I believe there's a bit of confusion here between malleable iron and ductile iron (the latter also being known as spheroidal graphite or SG iron). Malleable iron is an old process, that starts with white iron containing no graphite at all but lots of cementite. The part is then heat treated to precipitate the carbon out of the cementite, taking a more nodular form than standard grey iron. This means you can only really do it for components that can be cooled fast enough to solidify completely as white iron, which leads to a preference for small components and thin sections. Cylinders aren't viable this way.

SG iron has additional alloying elements (magnesium or cerium) which cause a composition otherwise similar to standard grey iron to solidify with spheroidal graphite as cast. SG iron post-dates most steam locomotive development, but gives mechanical properties similar to low carbon steel with an ease of casting similar to grey iron, making it very good for cylinders if you have liners.

 

"Design - Bogie Components
05/03/2019

Our design team are busy working on the Computer Aided Design models for the front bogie. We have most of the British Railways drawings for the bogie components; a CAD model usually is a great help to potential suppliers. One problem area is the axle cannon boxes which were supplied by Timken, most of the other components were designed and built in BR workshops. The cannon box is a single steel casting comprising of 2 axle boxes separated by a tube. The axleboxes contain taper roller bearings for the axle to revolve in. The cannon boxes were originally lubricated by oil but this was changed to grease. Once we have drawn up all of the components in the cannon box, we will get our CAD models checked by Timken before proceeding to manufacture."

More news from the Clan team... are other suitable roller bearing suppliers available these days ? are is Timken the only one left ?

 

As regards Bearings, SKF, FAG and various other manufacturers, mostly of SE Asian countries origin, but I personally would stick with Timken, SKF or FAG, you could also look at U.S. manufacturers to broaden your view..