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

Tornado also has a steam driven turbo alternator and is about to be fitted with an additional one as part of the ETCS installation.


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I seem to recollect that a mainline group, which may have been A1, were thinking of installing a generator/alternator in the support coach, but perhaps that was for the needs of the coach.

 

Yes there’s one under the support coach too. Both these axle driven ones have just been uprated too.

 

One of my thoughts was to put a generator in the support coach. We had a discussion with Tornado's crew when Geoff and I had a look round the electrical system in the spring. They told us that there will be times when the engine will have to operate without the support coach. Possibly this could be limited and batteries would suffice.

Yes, we will need to consider power when the engine is stationary.

At the moment, maybe a watching and monitoring game is the best approach. Most electronics as they evolve get smaller and more efficient. We need to study the outcome of the trials currently planned for ETCS.

 

Yes Ian, I think time is very much on your side here !

 

I was recently told by one of the ETCS test engineers based at Machynlleth that the ETCS electronics now could be reduced to about the size of a shoebox and that it will not be too long before it will be possible for steam services to return to the Cambrian Coast line.

As for support coach generators, the "Queen of Scots" coaches had underfloor generators that were barely audible even if one was standing next to them. I'd say that's the way to go!

 

This all sounds very encouraging and well in hand.

 

https://www.raildeliverygroup.com/m...g-gn-nti-005etcson-boardequipmentv2/file.html

That link should work. It gives a rough idea on the amount and size of the equipment required for ETCS. The Ansaldo equipment fitted to class 158s is massive. The Siemens equipment much more manageable. If the Judicial Recorder Unit (JRU) replaces the OTMR box, there isn't that much more equipment to fit. The biggest issue will be finding somewhere to fit the balise underneath. I've no idea if it needs to be located in a certain place (TPWS aerials are behind the first axle usually) but it seems to be behind the leading bogie on multiple units.

 

interesting stuff thanks.


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Do small steam powered turbines not cut the mustard anymore for electrical generation?

 

So when it's fully been built, steam tested and ready to run, where's it going to be based? Scotland?

 

Wherever the demand is, same as other main line locos I’d say.

 

I worked on the development of avionics for the BAe Tornado. - one of the major upgrades was a 64k memory version of the main computer. It just shows how fast electronics have developed. What was impressive was how much you could do with that size of computer. We have so much resource with modern computers that it encourages sloppy computing. In the 1970's every bit counted!

 

As an update on holiday progress, just before Xmas John Hind visited the NRM and managed to photo the minute books from the Chief draughtman's meetings in 1950 /1951 and the Locomotive Standards Sub-Committee meetings from 1959 to 1961. Although the latter minutes cover a lot of diesel loco development information, there's still a lot on information of steam loco development. We're still digesting the minutes - one interesting one was an experiment with direct lubrication to the cylinders as opposed to atomised steam oil lubrication. A significant improvement in ring wear was recorded.

 

Wardale used direct lubrication to the valves on the Red Devil, with an interesting construction of the valve and lots of very small section rings. The valves were successful, he was targeting extremely long valve exam intervals, and I think he might have tried direct lubrication for the cylinders too. Unfortunately his modified piston construction failed due to the way the bronze wear surfaces were deposited, and they had to resort to standard pistons. Part of the reason for direct lubrication was that applying oil direct to the walls keeps the oil cool and thus reduces carbonisation, which is handy when you're targeting over 400 C steam temperature.
His book contains quite a lot of information on the general design principles of his valves and pistons, and also how he would have done it differently if doing it again.

 

Have a look at

https://www.theclanproject.org/design/Clan_Design_Clip.php

 

It's been yonks since I last visited that page, so many thanks for the reminder.

There's a comment on the page concerning boiler pressure (225 vs 250 psi), which mentions the differences in (firebox) metal section between the 'Clan' and 'Britannia' classes. Does anyone please happen to know whether the question raised back then has been resolved and if so, what decision has been reached?

 

Here you go.

https://www.theclanproject.org/design/Clan_Boiler.php

We have also considered the impact on the centre driving axle. Class 7 Britannia's share the same leading and trailing driving axle design as all of the driving axles on the Class 6 Clans. However, the Class 7 middle driving axle is to a different design. We assessed the impact of the higher boiler pressure and higher tractive effort on the centre driving axle of 72010 and concluded that we would still get an acceptable bearing life with 250psi and the original class 6 design. So no changes required.

More information, just before Xmas we issued Request for Quotes for the machining of the bogie cannon axle boxes - cast by William Cooks - and for the manufacture of the internal components for the cannon boxes

 

The increase in Boiler pressure is something that i mostly support, with potentially a greater reserve of power when needed and potentially better efficiency. The cost will be mostly a modest increase in weight and potentially more frequent boiler repairs.
My major concern is the loss of certain unique characteristics of the Clan, other than its gracile appearance and silly Patriot-esque chimney (which may already be gone} , its light weight for such a large machine and despite this its surefootedness - on paper at least the best factor of adhesion of any British pacific.
So the draughting improvement increases steam raising and/or efficiency, and the increase to 250psi allows greater stamina and efficiency - the potential of the original design has been maximised within 1st generation steam parameters
To my mind the Downside is the notable increase in Tractive effort; with 19.5inch cylinders at 250psi and a loco weight of 90 tonnes gives a factor of adhesion slightly worse than a Britannia and my ( and that of Riddles and Cox) opinion on this matter is that adhesion is the most valuable asset and should not be sacrificed - an impressive TE and the on paper capability of hauling a couple of extra bogies are a vision easily dispersed when the loco. can not keep its feet.
The simplest counter measure being to decrease the cylinder diameter by a considered amount, either by thicker liners ( which is reversible) or at the design stage which has a potential gauging benefit ( however that boat my have sailed)
The other thing to take note of is that by increasing piston thrust and the change of coupling rod design is that Balancing/ Hammer blow is affected. Dont know if the relative values for the Britannias with rectangular section Rods and the Clans with I section Rods is still available to us to allow some sort of interpolation, but i do recall that the Brit and the GWR county are bottom of the class in that regard

 

Ah, you're very much there already. I'm glad to see this sort of hidden refinement in detail design getting an outing in this country, extending intervals at which maintenance is required is the sort of cost saving that has very little downside.