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Author Topic: Smoke deflectors  (Read 2712 times)

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Offline Hailstone

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Re: Smoke deflectors
« Reply #30 on: April 10, 2018, 08:57:43 pm »
1  taper boilers were a feature on all four companies locos
2. most tender engines were set at 225lb/sqin except the KIngs and Counties which wre 250lb/sqin. however, the blast from the chimney also relies on how open the regulator is and the setting of the cut off - anyone who has driven a loco with a steam chest pressure gauge will know this
3. length of smokebox is irrelevant as the chimney sits under the blastpipe in ALL locos, and for the record a double chimneyed castle has the chimney set towards the front of the smokebox
4 the Counties were found to steam best with a ridiculously short double chimney, which a lot of people said ruined its looks (I am not one of them)

1. how many LNER or SR Locos can you name with Taper Boilers?
2. most larger LMS locos were 250psi+.
3. the combination of the length of smokebox and position of chimney therein dictates the distance between the front face of the smokebox and the chimney. This was proven in the LNER's experiments to be one factor in the air flow and it's effect on the smoke flow...
4. "steaming best" is a factor of airflows within the loco which has only a minor influence on the airflow above/around the boiler and it's impact on the flow of smoke after it has left the chimney...

Ignoring streamlined locos: Gresley A1/3, Peppecorn A1 & A2  Rebuilt Bullied pacific N N1 u & U1 moguls
even Maunsells King arthurs S15's and Lord Nelsons were slightly tapered.

Regards,

Alex 

Offline PLD

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Re: Smoke deflectors
« Reply #31 on: April 10, 2018, 09:19:53 pm »
1. how many LNER or SR Locos can you name with Taper Boilers?
Ignoring streamlined locos: Gresley A1/3, Peppecorn A1 & A2  Rebuilt Bullied pacific N N1 u & U1 moguls
even Maunsells King arthurs S15's and Lord Nelsons were slightly tapered.
Gresley A1/3, Peppecorn A1 & A2  - All had ONE tapering ring within an otherwise parallel boiler. Not tapered boilers in the regular sense...

Rebuilt Bullied pacific - so only after rebuilding by an ex LMS man in BR days...

Online Train Waiting

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Re: Smoke deflectors
« Reply #32 on: April 10, 2018, 09:40:12 pm »
Gresley A1/3, Peppecorn A1 & A2  - All had ONE tapering ring within an otherwise parallel boiler. Not tapered boilers in the regular sense...

Rebuilt Bullied pacific - so only after rebuilding by an ex LMS man in BR days...

What an interesting thread; thank you.  Now Eastleigh is a long way from where I'm sitting, but I'm not sure Mr Jarvis' rebuilding of Mr Bulleid's 'Pacifics' did much to the boiler apart, of course, from reducing the working pressure to 250psi.

With regard to the LMS Class 5 and '5XP' 'Jubilee' locomotives, I rather think that their longer chimneys (a bit like GWR locomotives) gave adequate smoke lifting characteristics.

Best wishes.

John

'Why does the Disney Castle work so well?  Because it borrows from reality without ever slipping into it.'

(Acknowledgement: John Goodall Esq, Architectural Editor, 'Country Life'.)


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Offline stevewalker

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Re: Smoke deflectors
« Reply #33 on: April 10, 2018, 09:50:11 pm »
unlike the other three, the Great Western used Welsh steam coal which was softer and had less sulphur than the hard coal used by the others and required more primary (through the grate) air and a fiercer draught to make it burn more economically, which is why you will hear people say that Great Western locos have a more pronounced "bark" to their exhaust than other locos (and also why you see fewer "clag" photos of them in GW days)

Regards,

Alex

From personal experience: My local Model Engineering Society (Urmston and District Model Engineering Society) has a 2200', dual-gauge (3-1/2" & 5") circuit. They always used to use Welsh steam coal, but supplies dried up. The available replacement is awful, with very smokey, sooty exhaust, full of gritty lumps that hit passengers in the face. The Welsh coal, was so much cleaner burning.

Offline martyn

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Re: Smoke deflectors
« Reply #34 on: April 11, 2018, 08:52:37 am »
The Bullied pacific boiler was indeed only slightly altered when rebuilt-it was designed to be, and was, free steaming. But more to the point, the exhaust systems tried by Bullied on his locos were designed to reduce cylinder back pressure on exhaust-hence the need for deflectors to lift exhaust steam.

The pacifics' original air smoothed casing was designed, amongst other things, to be a smoke lifter, I think.

Martyn

 

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