The 10A Allocation

Indeed, as an example a Britannia and rebuilt Bulleid are both 75mph but the former has rollers, the latter plain whilst both have 6' 2" drivers and are Pacifics.

 

But you’ve read the magazine so you’ve read what it says. You don’t argue with some content but do with others

 

Eh?
I'm not arguing with the magazine report, I'm agreeing with the technical analysis others have made vis bearing/driving wheels differential on permitted max mph.
As you said David Smith says 4767 can go faster because it has rollers and that's what the magazine reported. He obviously has a different understanding.

 

The criteria for 75mph running is driving wheels over 6’ 1” diameter, the fact they are Pacifics is irrelevant.

 

Yes I know, I was simply pointing out John that there was no difference in max speed using 2 otherwise very similar designs, dimensionally where one has rollers and the other does not.
The analogy being that black 5s are all 60mph so the addition of rollers to 4767 would not, in itself, seem to be why a higher max speed would be permitted.
Having delved into the memory, didn't Bert get 5231 approved for 75mph or am I misremembering?

 

Its a bit of a daft system - neither example is mainline approved or likely to be - but a 9f would be limited to 50, A Beattie well tank or Dukedog good for 60....

 

I seem to remember that was 5305, only for a brief period when it returned to the mainline in 2005.

 

Thanks, we might be getting mixed up here as I think 5231 went mainline around 2005 but 45305 returned a bit later, maybe 2010?
I also have some memory of Ian Riley stating he didn't think it was wise to have LMS 5s 'plated' for 75mph but again I can't remember quite where that anecdote entered my head

 

Pictures on its Facebook page suggest that the chassis and wheels etc are progressing, plus possibly more significantly, when I passed the other week I noticed that its boiler which has been prominently stored outside and visible from the station for ages has vanished from that spot.

 

It's why Stanier created the 5XP after all, longer legs and 3 pots for high speed.

 

45305 did initially return to the mainline in 2005, mostly on runs by VT but then had the rough shunt at Loughborough the following year. It was 2010 when it re-entered service.

 

Thanks for putting me straight, so about the same time as 5231 was first certified under Bert Hitchen's ownership?

 

Yes, seem to remember 45231 was a Steam Dreams regular during that time.

 

A Beattie Well Tank at 60? Where do I sign up?

Tom

 

What would be the limit for the Stirling Single?

Jon

 

The Aero limit of the drivers hat

 

Spotted earlier this week at the north end of the boiler shop.

 

Correct, I had a run to the Crewe open day behind it which was just after its 75mph 'trials'. Suffice to say a late departure was more than made up by extensive demonstration of its capability of running at the higher limit! Remains one of my best runs behind a 5 on the mainline.

 

RSSB RIS 4472 Appendix D states that Black 5's are limited to 65 mph. Jubilees, Scots and Princess Royals are 75 mph & Duchesses 80 mph, as are A4's and the A1. Owners can specify lower maximum speeds. It is possible to apply to the RSSB for a higher speed than laid down in 4472 if you have a good case and this may have happened.