MHR Restorations and Overhauls

The fitting of rocking grates also requires the fitting of hopper ashpans.

 

There are several locos out there with rocking grates/drop grates and rake out pans. 5224, 6619, 45212, 45428, 60007 & 60800 immediately come to mind. I'm sure I can think of others if I try¬

 

That does suprise me, Steve. Is the fire dropped into the ashpan at disposal? Would have thought that this could lead to some distorted ashpans.

 

It is not only the main driving axle bearings that create significant losses and make the loco roll freely. It may not be practical to redesign the main axle box accepted.

However there are 3 bogie axles as well without looking at losses in the motion area.

My main interest is to not have to do any mechanical work at the 10 year or longer term overhaul as well as removing the continual service time during preparation on cold wet mornings.

Redesign is about long term investment , and future reduction in hidden cost, or forward financial loading.

I am very much a man of "If it ain't broke don't fix it" but at a major overhaul stage I would willingly improve design to help me in the future.
Many engines suffer failed axle journals in service,for all sorts of reasons, this is a big hidden cost and risk area financially as well as loosing service time to correct failiures.

Its not about doing only 25 MPH its about how long you can do it for without attention.

Rolling resistance for plain bearings is 8lb per drawbar tonne and 7lb using roller bearings that's not taking into account bearing stiction to overcome from a standstill. With plain bearings there is stiction with rollers there is not.( Ref Timken Railway catalogue 1950)Why did SAR adopt a major policy on this topic.

Live now and in the future not in the past just because we did it that way and will alway's do it that way.. Best Regards

 

The fire is dropped straight into the ashpan and, yes, you have to be ready to slake it down and rake it out. It needs a bit of cooperation between the guy dropping the fire and the guy who is raking out. Some of these locos have ashpan sprinklers, as well, which helps. Most are post preservation mods but the Gresley locos with their drop grates are unchanged from BR days. In this respect, I'm sure that 61994 is the same. Can't be certain about 60009 & 60019.
Oh, and you can add 825 & 30926 to the list!

 

One big advantage of rolling contact bearings is their low starting friction compared with as plain bearing. However, once an oil film has established, a good white metal bearing probably has a slightly lower rolling resistance than a roller but it is marginal. Rollers offer other advantages, such as close tolerances and thus the ability to be effectively enclosed. They are higher on first cost, though and less 'maintainable' in the field if you are unfortunate enough to have problems.
SAR obviously had their reasons for fitting roller bearings and these were almost certainly sound. BR, on the other hand, decided that rollers were not worth it for the majority of their Standards. Their reasons were no doubt as valid as those of SAR. I'm pretty certain that roller bearing technology has not advanced so significantly that the reasons considered by BR are no longer valid. Axlebox troubles on BR standards were pretty much non-existent, as far as I'm aware. Why change something that works for the sake of it? You wouldn't be improving the design. And that isn't about living in the past, it's about common sense, really.

 

In support of 'Steve', I can well imagine that the SAR used rollers because, if they were grease filled and totally enclosed, they would be resistant to dust and grit ingress. Plain, oil lubricated, boxes would have a problem in the SAR context.

Modern SAR designs also had wide fireboxes, supported on trailing trucks. It would be far easier to 'design in' rollers in these types than the narrow fireboxes of most BR designs. I suspect that was part of the reason that some Cl 5 locos, LMS & BR, only had rollers on the driving wheels not on the coupled.

With respect to 'TheEngineer' the idea of retro-fitting a Brighton Tank with rollers is just not a goer!

Regards

 

Are readers generaly saying that because the main axles are not a good idea you would not consider the pony trucks Rods and the motion ??

 

Whilst we're on the subject of drop grates and hopper ashpans. can I please petition for those marvellous labour-saving aids to be fitted to Lord Nelson while it's out of traffic? Love it to bits and all that, but it's a truly horrendous beast to clean out, only remotely forgiveable because it's a unique and priceless national treasure. The current grate is a ropey old thing anyway with an assortment of ill-fitting firebars, some of them stamped "N15" crammed in amongst others of more indeterminate origin.

I suspect the NRM would consider such improvements sacrilege, but no-one except the crews would ever see them anyway, so what would really be the problem?

 

The Std Class 5s had roller bearings fitted throughout including the bogie. The only variation was that 73090-99 were fitted with skefco instead of timken roller bearings on the driving and coupled wheels.
The Class with variations was the Britannias. 70000-34and 70050-54 had roller bearings fitted throughout. 70035-39 had plain bearings fitted to the leading and trailing coupled wheels. 70040-49 had plain bearings fitted to all driving wheels and the pony truck.

 

Thank you Std Tank for this detail. Does anyone know for sure what were the outward impressions from BR Development after the designs had run.

I understood that the changes were well acepted and costed out as being superior in respect of cost, longevity and efficiency in operation , only realy killed of by the "Dieselisation Program".

Am I wrong in this view??

Certainly the Bogie program for rolling stock followed especially citing the "Comonwealth" as leading the field, then the B4, giving much longer wheel profile life and service interval with superior riding throughout life . If plain bearings were so acceptable, why were they phased out on rolling stock so quickly.

Modern polymer oil seals now make sealing bearings much more reliable, and flexible "Bearing Technology" has moved on , as have the lubricants they are packed with, the sizes of the bearings , style of rollers and dynamics have improved to allow much slimmer designs to be fitted in spaces that previously , 50 years ago were not feasable.The loads permissible have also gone up as have the corresponding RPM , not that for loco's RPM is an issue.

I get the impression we have a fear of the unadopted. Perhaps "Tornado" should have been built with all plain bearings?? because they are good enough. What's the view??

 

E.S. Cox's book on the Standard Steam Locomotives could provide the answers about the Britannia variations.

 

Steam locomotives weren't really intended to run at 90mph on a regular basis and plain bearings were adequate for them. The change with coaching stock bearings came with dieselisation and the higher speeds possible - plain bearings weren't really up to prolonged high speed running.

 

I don't think that rotational speed is anything of a problem with plain bearings. I'd suggest that the change to roller bearings was more driven by the desire to improve on the riding qualities of the Mk1 bogies and the reduced tolerances that roller bearings allowed. The sealed, grease lubricated roller bearing also offers huge maintenance savings.

 

I think that you've already provided the answer to your question in your last sentence.

 

Best bet on that one is ask NRM the question with a good case to put , at the end of the day the crew will treat the loco better if they are happy with operating it, and happy with the interaction with the owner, its a two way street, jobs that are a bitch usually get half done, its not much fun late at night.
"You don't ask you don't get" always works for me worst they can say is no.

 

Talking about improvements on Std tanks, Doncaster Works drawings office drew up plans to fit the contingent working on the L.T.S.R. with double blastpipes and chimnies. The chimney to be used was an LMS one, presumably the type fitted to the Ivatt 4 2-6-0s. Would that be an experiment worth doing, but using the double blastpipe and chimney as fitted to the Std 4 4-6-0s

 

Thank you for this, of course I was in error about rollers on the BR5 ... just looked it up in the RCTS book to confirm the mistake!

It's interesting that the bogie on the roller fitted BR5 engines would be non-standard versus the plain bearing Brits, BR4 etc locos. If the MHR took up 'TheEngineers' suggestion, I wonder if that would mean scrapping the existing pony and bogie trucks? Probably would.

Regards