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

In a book by Paul Beevor(?) he suggested that the trouble with BR was that locos tended to stick to their original lines. He continued with BR should have taken a look at the entire stock and had say, MNs working Liverpool - Glasgow, WC & BBs Leeds Carlisle and transfer V2s and Black 5s to the Southern.
But this is digression; back to the Hengist topic....

 

Were the BFB wheels patented? In any event, there was plenty of expertise on how to make spoked wheels, and quicker to use that capacity than go down the path of spreading the expertise?

In terms of boilers, Bulleid Pacifics did have a hefty appetite for coal, so were not perfect. One of the locomen books commented they had no dampers, which meant they were always wasting steam if the crew wasn't absolutely perfect letting the fire run down before station stops etc

 

He's got a point, but can you imagine the chaos? Pretty much the whole WR outside South Wales infested with 'not invented here' syndrome; the angst when WR sheds in the West Midlands were transferred to LM, or ER sheds on the GC ditto; the completely different performances of the L1 - fine or absolutely hated depending on which shed you talk to....

Sending locos to where they could do a job is absolutely logical - it just ignores the crews, the maintenance regimes (and locations), etc.

 

Wasn't that only true of the earliest MNs, as built?

 

You have to think about Route Availability as well - loading gauge and weight limit. The light Pacifics were built deliberately for use on lines with a low axle load limit and restricted loading gauge - on the South Eastern section, often they replaced pairs of 4-4-0s previously needed for heavy trains.

So hypothetically - you could send 50 light Pacifics to the Western Region, but what then? You couldn’t automatically cope with 50 Halls in return because they wouldn’t fit.

Tom

 

Nope. The MNs had dampers from day one, though they were modified on rebuilding. The LPs had no dampers to start with, but they were added on rebuilding. Free grate area on the MNs was reduced on rebuilding as well from 50% to 30 something%

 

What’s the “free grate area”? I’m curious about that change given that I wasn’t aware that much happened to the boilers on rebuilding.

Tom

 

Free gas area?

 

I wondered that - but in which case, why did it change so dramatically on rebuilding given the boilers were largely untouched?

Tom

 

Was there any change to the superheater elements which might alter it?

 

Not that I’m aware of. There was a small change to the arrangement of taper between the earliest and later MN boilers, which reduced weight without any other significant change. Boiler pressures were reduced from 280 to 250 after a period in service. But I’m not aware of any significant changes to tube or flue layouts.

Tom

 

Area of firebars relative to the air space between them?

 

Space between the fire bars I think. Weight diagram for the original quotes 50%, for the rebuilt it came down to 30 something%. The only significant changes were the firegrate and below it (dampers, ashpans etc.), reduction in size of the superheater header, and the change to the chimney. The modifications to the exhaust massively improved the smokebox draught produced, which was necessary due to the increased resistance to air flow for the air coming into the firebox

 

The superheater surface area was reduced a bit, mainly in the header I believe, in order for it to fit into the round smokebox, I don't think the tubes themselves were altered, but I've not looked into that yet. Though we're digressing a tad from the Std 6...

 

Other than being detuned by reducing the BP to 250 psi - presumably the reduced maintenance costs offset the 11% loss of maximum tractive effort (or perhaps it was simply not required) - I've never heard that the boilers themselves were modified by Jarvis. Were the boilers interchangable (and interchanged) between the modified and unmodified locomotives?

 

I would think so, in theory, except if you put an original exhaust with a rebuilt firebox, you might have some issues due to poor draughting. The other way round you might have the reverse problem (excessive draughting). On 35011 we're likely to have something other than the original exhaust for that reason. The 30psi reduction happened before rebuilding, and we won't be reversing it. More information is available via the GSN thread of course or www.35011gsn.co.uk (apologies for thread drift!)

 

Given when the rebuilding program occurred, I've often wondered to what extent the growth of car ownership was eating into passenger train weights. The 'magic number' on the Southern seems to have been the ability to shift 500 tons (was that behind the tender, or including the loco?).

For comparison purposes, the 13 car CEP/BEP/CEP/MLV formation most usually seen on services between Victoria and the Channel Ports tipped the scales at something just short of 530 tons.

 

Was this because finger bars similar to those used on Standard loco classes, were used for the grates on the rebuilds?

 

Lots of progress today - see https://www.theclanproject.org/Clan_News.php

We now have 4 bogie wheels on their assembled axleboxes. 61 tons minimum force is required when pressing on the wheels and all 4 wheels exceeded this. Next stage is to turn the outside diameter on the wheels.

On the bogie frame, fitting the frame plates to the stretcher is complete and we have started to install the fitted bolts which involves a lot of heavy work with a copper head mallet.

Class8mikado - we do have a copy of drawing SL/BR/1678 issued in 1961 which shows that it applies to Class 9, 8, 7, 6, 5, 4, 4T, 3, 3T , 2 and 2T which looks like this



It doesn't list any engine numbers that it applies to and, no, the drawing isn't dated April 1961!

 

Was that an attempt to cure slipping on starting or just to reduce maintenance costs? I have pleasant memories of Merchant Navies slipping on starting away from Brockenhurst in a westerly direction and having to reverse for some distance before restarting.