BR Standard class 6 No. 72010 'Hengist' and Clan Discussion Thread

As far as the castings are concerned, there are no differences between Class 7 and Class 6

Drawing SL/DE/19578 applies to both Class 7 (70xxx) and Class 6 (72xxx). It does not cover 9F; that drawing is listed on the NRM drawing list as SL/BR/1034. The 9F Crosti is SL/BR/1255. I don't know what the differences are as we don't have those drawings.

For Class 6/7, the difference is in the cylinder liner. Class 7 uses liner item 1 which has an X dimension (internal diameter) of 1' 8" whereas class 6 uses liner item 2 which has an X dimension (internal diameter) of 1' 7.5"

Ian

 

I've had a quick look at both cylinder drawings.
The main differences are the distance from the outside of the frames to the centreline of cylinder bore and similar to the bore for the valve liners.
For the Britannias the dimensions are 1'-6 7/8" to the centreline of the cylinder bore and 1'-10 7/8" to the centreline of the bore for the valve liners.
For the 9Fs the dimensions are 1'-7 5/8" and 1'-11 5/8" respectively.

 

Thanks Std beat me to it, is the incline angle of the 9f cylinder relative to its frame mounting/pedestal also different ?

 

I believe that the 9F cylinder centre was one inch further outboard of the frames, compared to the Britannias, in order for the crosshead to clear the side rods.
It was deemed preferable to produce the 9F cylinders from a new casting than fit a spacer plate between the cylinder and the frame plate.

 

Now, you're getting technical. I'll have a look.

 

1 in 24 for the Brits (2.38 degrees)
1 in 10.25 for the 9Fs (5.57 degrees)

 

We love technical on this thread.....

 

Thanks for the answers chaps - considerably different then.
Cheers,
Ray.

 

Thank you. I think I had seen that but forgotten.

 

If you were Gifted a set of 9f cylinders at the outset then you might be able to alter the design of the mated parts to suit but otherwise, like most parts of a 9f, theres not much commonality with the pacifics.

I Note with interest that the latest preference is for a BR 1F tender, which am pleased about, suppose the profile of the raves can be changed so it looks more like the B/C/D/E/J if anyone is bothered by that

 

No Sean, 1F does not have raves but packs quite a bit more water, helps with range of mainline use. Heritage lines only do 25mph so the raves are not quite as important as on mainline, and who goes fast in reverse!

 

When Blue Peter suffered its accident on 1-10-64 it was footplate error which caused a significant wheel shift; design does not solve that, only full training of personnel, for every locomotive type! As 'owners' of expensive kit, don't we all expect that?

 

I imagine that BR locos are unlikely to suffer a Blue Peter type incident due to the difference in reverser gear design?


Sent from my iPad using Tapatalk

 

Howdo John, Thanks, am aware that a 1f is not an inset bunker tender .
To my mind raves are an upward extension of the side sheets above the level of the tank or bunker to give an ' improved' appearance and/or form a 'tools tunnel' ? ( The most obvious examples being on Air Smoothed Bulleid Pacifics or the streamlined 'Duchess'es).

 

Indeed so Sheff, my point was that unless the footplate crew know how to do their job then it doesn't matter how carefully you design controls, unless you make all engines the same of course!
I know NELPG spent a long time writing a Manual for footplate crew after that experience and insisted that all crew be passed on it before running the train.

 

Even the very wise cannot see all ends...(Gandalf)

 

Well I can see where you are coming from, but really the raves are a chunk taken out of the high-sided version to enable rearward vision. The tools tunnel can be provided whichever tender design you have.
Anyway, I look forward to hearing that the fund for the bogie has been reached and the extensions are fitted, hopefully before too long but we must allow the lads their Christmas + break, they have done very well this year.

 

Originally, a rave was "a permanent or temporary framework to increase the capacity of a cart". On railway locomotives, in the days when a typical tender was essentially a large tank of water with maybe a small box-like compartment at the front for coal. The coal was stacked on top of the tank, and "raves" or coal rails were added to stop it falling off the side.

From another discussion here on NP, I believe the same feature is called a "fender" on a GWR tender. They always did do things differently at Swindon ...

On Bulleid tenders as originally built (with high sides), the side extensions provided a tool channel (and married the profile of the tender to the loco); however, the "coal box" was separate and inside. Hence "rave" is not - by original usage - the correct term for that feature (because it doesn't per se increase capacity), though it is invariably used (and was used as such from when new I believe).

Tom

 

"Do you have raves on your tender?"
"Certainly not, we have a disco in the carriage shed, but that's as far as it goes..."