70000 Britannia

Flying Scotsman has been moved by road a lot, did it do it any harm? (dives for cover) but so has Black prince,
if they leave Cromwell there long enough it will be on a main line connected railway! so no issue

 

So have a LOT of Loco's.....................

The next one I know of is our 9F (92212) off to the NVR for their "S&D Gala"........ I wonder how many broken springs she'll suffer this time - right after the lads at Ropley have just put her right?......

 

Generally i would agree with the honourable Mr Meanley,
if you do not NEED to, don,t.

 

In steam days, loco bogies would drop off the road quite regularly (amongst a whole host of other derailments). They would be put back on the road with no fuss or bother, given a quick coat of looking at and back on their way.

 

But now we have a much better understanding being formed concerning what could well hide beneath the paint.

 

The problem with the wheelset was the rh driver had moved on its axle, sufficient to distort both the key and the keyway. It seems very likely that this would have caused the vibration as the rod bearings would tighten and then release twice a revolution as the pin to pin distances changed.

What caused the wheel to move is another question, but it seems to me it's more likely to be a slip recovery or something dynamic like that than just banging the loco about a bit. Did the wheels slip during the rerailing efforts? when did the vibration begin?

As to the bearings, given the difficulty of changing them it makes sense to renew if the wheels are taken off for any reason. Maybe the supply was a bit iffy.

 

So probably confirms the need to get the locomotive thoroughly checked out.

 

Just how it happened on an SA trip. 15F ran over a derailer and onto the dirt. Rerailed after a while, checked on the spot and resumed its duties the next morning.

 

Thank you L plus, A problem with previous for Britannia's ' not wholly solved. It will be very interesting to hear of any special steps taken when re assembling the axle/ wheelset to confound this condition. I would be interested to know if the wheel fixing on GWR counties is any different, not withstanding that a GWR county doesnt have roller bearings. I'm picking on the county because of its common ancestry and design features.

 

Perhaps part of the reason Cromwell was "last man standing" ?.

 

I'm not sure if the wheelset in question had been modified during BR days, or even in preservation. Interestingly at least one of the other driving sets doesn't appear to have keys.

 

Looking at the history of the Britannia Class makes interesting reading. Originally, the axles for the driving and coupled wheels had a 4-1/2" dia lightening hole through them. Following movement of wheels on axles, the axles were redesigned, as were the keyways. Solid axles were used and the keys were individually hand fitted to the keyways. (Sounds like a very good fitter fitted the keys on the wheelset, if they can't be seen, Lplus). At the same time the coupling rods were redesigned as well. Rectangular section coupling rods were fitted, instead of the original I section rods. There were 25 of the Class completed at the time and all were temporarily withdrawn for the modifications to be done. However, the problem of wheel movement was never cured.
There was never a problem with the members of the Class fitted with plain bearings, 70040-49. It is thought that the reason for this was the bigger diameter of the axles mating with the wheels, 9 1/2" dia for leading and trailing wheelsets and 10 1/2" dia for the driving wheelsets. This compares with 9" dia and 10" dia for the roller bearing fitted members of the Class.
I think therein lies the problem. Too small a surface area to hold the wheels securely in place.
I would put the wheel movement on 70000 down to a Class design problem and nothing else.
It is interesting to note that the 9Fs, all of which had plain bearings, were fitted with axles to the larger sizes as well.

 

Presumably this was because ( trying to visualise it) the journal size was dependent on the size of roller bearings selected and the axle end had to be smaller yet to allow the roller bearings to be fitted....
i am watching this with interest to see what bearing( see what i did there) it might have on the Clan.
Roller bearings certainly have their advantages and for the reasons touched on above and for simplicity of manufacture wondering whether a change to all three sets at '10 inch' would be an option worth considering...

 

It seems to me that any possibility whatsoever of a wheel rotating relative to its axle (and therefore also relative to the other wheels) in any circumstances other than severe overload (as for instance with Blue Peter's infamous slip) implies a serious flaw in the design. Std tank reminds us that it did happen with the Britannias early on. (And I seem to recall that the GE section borrowed some Bulleids to tide them over while the problem was addressed.) If it was never entirely solved at that time, it darn well ought to be addressed now, on the surviving Brits and on the new-build Clan.

What about the other standard classes? Is the keying more substantial on those? Have they ever had this problem?

 

No problems with the Clans or the Std 5 4-6-0s were mentioned by E.S. Cox. However, he mentioned that there were problems with some of the LMS Class 5s fitted with roller bearings.
Bill Harvey, Norwich shed master and renowned Britannia Class expert sent some paperwork about problems with the Class to his counterpart at Immingham MPD, when some Norwich Britannias were transferred there in 1961. In this paperwork was a note to keep an eye out for any protruding wheel keys. He also stated that 9 cases of wheels moving on axles had happened in the last three years (1958-60).

From reading the writing of these two experts, it would appear that the problem was with the coupled wheels, not the driving wheels.

 

You can't simply fit bigger bearings to allow for the use of a larger diameter axle. Roller bearings are physically larger than their white metal equivalents, and the horn gap in the frames has to be wider to accommodate them. There are limits as to how wide you can go, so the axle diameter was, presumably, reduced to compensate. Bear in mind also that the axle was no longer bearing surface itself so it did not need a large surface area from that point of view. But trying to fit a bigger bearings and axle now would involve a major redesign.

The problem of wheels shifting on Britannias is covered quite extensively in Eric Langridge's (the collected works of) 'Under Ten CMEs Vol 2. One of the problems with roller bearings was that the wheels and axles had to be pressed together and the assembly placed in the balancer and weights added as needed. The wheels then had to be pressed off the axle for the roller bearings to be fitted, when they would be pressed back on again. It's possible that this repeated process altered the fit of wheel seat and axle. This is a point to be borne in mind by those advocating roller bearings on all new builds: while they are more reliable and longer lasting, they will not run indefinitely and can fail, and while an axle with plain boxes can be quickly dropped (given the right facilities), the box remetalled and the engine soon back in traffic, a hot box with roller bearings is a major task.

 

Fascinating info here. I was aware that the problem related to the wheel moving on the axle, but did not appreciate the full background. Passing Ropley on Saturday as I am working on the Watercress Belle so I will look at 70000 with new insight thanks to this thread

 

I am afraid not. The horns are wider for the bigger bearings.