73096

Wow, ive never seen that before !
Lucky that didnt happen in a station or on the mainline at speed !

Is this in anyway similar to 45231's incident ?

 

As far as I am aware, the 45231 incident was similar, but differed due to the fact that it only blew the end cover off the cylinder, not the front third of the entire block, which is what seems to have dissapeared from 73096!

 

It's important we don't let this very unfortunate incident get out of hand. Incidents like this also happed in BR days from time to time and were dealt with. The snag is nowadays we don't have the cylinder pattern set to hand to cast a new one and replacements will not be cheap.


Confirming a previous posters comment: The present Bridgnorth patternshop isn't really big enough to make the tooling for the Std 3 so the slightly larger 5 is certainly a no no.

 

Tricky to speculate on that sort of thing... It probably depends on quite how the failure proceeded... I have a bit of experience with bike infernal combustion engines, and with those exactly how the machine disintegrates seems to depend on an awful lot of factors, presumably including rpm, where in the cycle the failure occurs, and of course exactly how the first thing that breaks starts to break... One time you can lose a valvehead and just have a few dents in the cylinder head to sort out, the next you may have scrap aluminium falling out of the carburettors before you even get as far as taking the cylinder head off (and a very unpleasant discovery too if its your own hardware he said ruefully]...

[added next day]

Also, I guess weight is always a consideration, so are any components likely to be much stronger than they need to be for when the engine is functioning as designed? The cylinder castings and covers are surely not going to be any more robust than they need to be to operate normally (which presumably involves a lot of complicated torsional stress on the cylinder castings, so my completely unifomed guess would suggest they need to be stronger than the end covers). Could someone who knows about the engineering design decisions comment?

 

Following from the immediately preceeding post. LMS practice, and hence probably BR Std, was to have a groove machined in the cylinder cover to weaken it slightly such that it was more likely to let go than the cylinder itself. I have no way of knowing whether or not 73096 had such a groove in the cylinder cover; but I can confirm the idea of that groove hasn't always worked in practice previously.

 

I totally concur with this. Well said. Indeed we certainly would always stick by our locomotive through good times and less good times. That is what preservation is all about. All steam locomotives are precious commodities and its the devotion of people to those engines that is what it is all about surely?

FC

 

"My god that is some serous damage!" Was my first thoughts on seeing the pictures on the Mid-Hants website. And you are quite right in that you should stick with your engine. No point in feeing just because it's damaged since this is the time they are most needed.

Not to point out the obvious but since a new cylinder is now needed surely all the other Standard 5 groups could chip in towards the cost of the pattern as it would be in there best interest for one to be created. Just a thought.

 

Surely the time span on a new casting and any new rods would be a matter of months - Or even closer to a year?

 

Both 7325/9303 and 8233/48773 at the SVR have suffered identical core plug failures in the past. The 2-6-0 was lucky and only ended up with bent rods. The 8F had a similar cylinder failure to 73096's, with most of the front stud ring broken off.

There are specialist companies out there who do casting repairs and I would suspect that the MHR will explore the possibilities of repairing the existing cylinder rather than making a new one. The SVR's 8F was repaired by this method.

 

Would it be possible to fabricate a cylinder, I think it's been done for smaller locos and is proposed for the G5?

Dave

 

Without studying the drawings I note there is only a small dimensional difference in the bore of a 73XXX to that of a Black 5 (from which the Std 5 was developed). It might be worth checking to see if the same pattern set can be made adaptable for both.
If, as is likely, it is possible to make a pattern set to suit both classes (or even perhaps others such as an 8F too) the tooling cost per unit would be that much lower.

 

Too many pieces, scattered over too wide an area, I think! A small number of clean breaks can be repaired, but the damage in this case is of a different order. Have a look at the pictures on the MHR website (link in one of yesterday's posts).

Another poster (not sure if in this thread or the MHR Gala thread) said he thought one of 73096's cylinders had already been repaired. If so, and if it was the one damaged in this accident, then that might explain the rather more extensive damage in this case than for either 45231 last year or 48773.

Someone suggested earlier that there were three basic cylinder castings for all the BR standards, that were then machined differently for the individual classes. Can anyone throw more light on this? Which version (large, medium or small) does the Class 5 use and which other classes is it shared with? As suggested earlier, if it's the same as used on the Class 6 (72xxx Clan) then there's scope for co-operation with the Hengist project. I'm not sure who else, at the moment, is in the market for a new BR Standard cylinder.

 

Now you are thinking! To my knowledge, nobody else is in the market for cylinders of this sort of size.

OT I know but, other than 43106 and 82045, does anything else use 17 1/2" x 26" cylinders?

 

Sorry Boldford, do you mean "if it's the same bore and stroke, then....", or have you looked it up and found that the class 5 and class 6 designs do have the same bore and stroke, and therefore must use the same casting? As I said, it's not my idea. Someone else posted it earlier, but it slipped under the radar amongst all the "isn't it terrible" posts.

 

Not nice to hear of something happening like this. Something not picked up on as yet is that with the exception of the small BR Standards is that instead of cast iron for the cylinders, they were made of steel with cast iron liners. E. S. Cox refers to them as being "almost indestructible" - I'm afraid he was wrong in this instance. However, being of steel serious forces must have come into effect to cause this extensive damage to the cylinder casting itself rather than the front cover just being blown off. As steel can bend, rather than just fracture in the case of cast iron, a weld repair may well be difficult if not impossible due to the remains being distorted. Shrinkage rates for iron and steel differ, so an existing pattern unfortunately may not be of much help.

Steel is not the best material for ease of casting, and if I recall correctly, the 71000 people opted for the 1950s developement of SG iron, which incorporates the advantages of both steel and iron both in ease of casting and machining.

 

The cylinder castings for the Clan and 73096 are different designs. People are forgetting that the back to back frame dimensions of a Clan are smaller than a 5, thus requiring a wider cylinder casting. Also the bore of the cylinder of a Clan is 19 1/2" dia not 19"dia.
Eightpot I beg to differ on your statement about steel cylinder castings. 73096's were cast iron.
Std Locomotive Cylinder Castings were as follows: -
70000s & 72000s same casting. Material Steel
73000s Material Cast Iron
75000s & 80000s same casting. Material Cast Iron
76000s Doncaster drawing Material Cast Iron
76000s, 77000s & 82000s Swindon drawing same casting. Material Steel
78000s & 84000s same casting. Material Cast Iron
92000s Material Steel
The steel cylinders were fitted with cast iron liners , but all the others could be fitted with cast iron liners as well, once the cylinder bore reaches its scrapping size.
From the MHR photos I would say that 73096 did not have a liner fitted, but I may be wrong.

 

Re: MHR 5MT 73096

I would imagine it will be #850 LN. #60019 is currently away at the WSR and the boiler ticket extension on #41312 was only for the Gala so #850 will probably be working the services alongside #34007 which is rostered for this weekend.

The loss of #73096 is going to leave a big hole in the roster as she was going to be used for mid-week footplate experience courses. I don't know what will happen with these now.

 

Hang on to all those broken pieces, 73096 - the new cylinder fund will be able to raise a few pounds for them at auction - after all a piece of cylinder is (fortunately) very rare!