The 10A Allocation

As I say that’s quoted from David Smith that 4767 can do 75mph in the latest Trackside

 

Is that a typo for 65 mph?

RSSB RIS 4472 states the following:
G D 1.6 The steam speeds formula takes into account:
a) Wheel diameter rotational speed of 6 revs per second.
b) Piston stroke and oscillation speed of 1600 ft per minute.
c) Number of cylinders (see G D.1.8 b)).
d) Presence of leading pony truck or bogie to add steering and derailment resistance.
e) Age of original design (see G D.1.8 a)).
G D.1.7 Derivation and application of the steam speeds formula is overseen by RSSB, to whom requests for access may be addressed.
G D.1.8 The following general criteria have been applied to the speeds derived:
a) The cut-off for age of design (by which a lower speed is allocated) is 1923. This date is suggested partly because it is the date of the post WWI ‘grouping’ (that created the London, Midland and Scottish Railway (LMS), London and North Eastern Railway (LNER), Great Western Railway (GWR) and Southern Railway (SR) ‘big 4’) but also due to the landmark bridge stress committee work, begun in 1923 and reported in 1928. The output of this work, including the determination of the hammer blow effect, influenced locomotive design philosophy thereafter in a manner beneficial to track force considerations.
b) 2-cylinder locomotives are those most prone to display the ‘hammer blow’ effect as there is no natural balancing to the effect, with piston sequence at 90 degrees. By contrast, 3-cylinder (120 degrees) and 4-cylinder (180 degrees) locomotives are naturally better balanced and exhibit a less pronounced effect.
c) The additional rear wheelset on the 4-6-2 pacific types, although adopted mainly to spread axle load, generally offered additional benefit in ride quality; conversely, certain 4-6-0 types displayed deterioration in ride quality as speed increased. This has therefore been taken into account in setting speeds for the two generic design types.
d) A marginal increase in maximum speed (75 > 80mph) has been allocated to certain pacific types with 6' 8''driving wheels or greater, on the basis that this is a significant increase over 6' 2'' (the basis for the previous maximum limit for 75 mph when operating on the GB mainline railway). One consequence of this is the requirement for fixed rather than portable headlights, as set out in 3.7 where operations are proposed at that speed.

 

I don't believe so Steve, I've heard it said a few times that 75mph will be permitted. Perhaps the owners have had discussions with their vehicle acceptance certification body and made out a technical case as to why 4767 can be treated differently to the other LMS 5s? There was clearly a case made for 45305 20 years or so ago, as a test run was carried out. Presumably WC was the operator of 45305 in 2005 at the time of the 75mph trial?

 

44767 was given permission for 75MPH as the loco was proved under testing to give less hammer blow than a standard black 5.

Coupled with roller bearings it had 75MPH classification in its last mainline stint

 

7802 Bradley Manor was also passed for 75MPH running to allow it work the Torbay Express trains and that has 5' 8" driving wheels

 

Can't remember precisesly but guessing that 44767 was last on the mainline best part of 25 years ago, maybe longer, so the testing was probably under BR auspices and pre 'VAB' regime?

 

A close guess, 18th Feb 1998 was its last run!

 

All true but perhaps the latest owner of 44767 is less concerned about conservation or not too worried about the costs of maintenance due to having full workshop facilities 'in-house'?

 

Good grief, where does that time go? I remember it came in to ELR around that time via a railtour (Pilkington set!).
So it would have been certified around 1991 and the 75mph testing presumably assessed by Brian Penney?

 

Couple of Shots of 44767 ,Banavie 09.09 .1984,with Ben Nevis in the background, and passing 15A Wellingboro Round house. Still standing in 2026 ,listed I think,on a St Pancras to Stockport train ./03/1995

 

I’m sure this’ll have come up somewhere else, but what was the rationale for 4767 being built with Stephensons in the first place? It seems a pretty unusual outlier if there wasn’t anything wrong with walschaerts in the first place!


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