Current and Proposed New-Builds

Only made possible by the use of the boiler from the Nord "Superpacifics". Chapelon simply asked the Nord for the drawings and they obliged. A bit like the GWR supplying 50 Castles to the LMS - oh, hold on a minute!

The same boiler was also used on the 150B and 150Ps.

 

Hopefully in the firebox.

 

Wide firebox over five feet drivers anyone?

Chapelon 240P-overlay(4) by Hermod posted Apr 1, 2022 at 8:41 PM

SNCF 4-8-0 plus 9F same scale and the 4-8-0 was measured plus 4100 IHP

 

Despite Hermod’s best endeavours, I was rather struggling to see where the firebox was going to fit…

 

As indicated above by @RAB3L, the Chapelon 4-8-0 boiler was based on that of the Nord Rly" Super-Pacifics", which used a long narrow firebox. See attached diagram.

Think of a GWR "King" with an extra pair of carrying wheels to spread the weight. The "Super-Pacific" boiler barrel was a bit shorter than the "King", but the firebox was even longer. However, unlike the large GWR 4-6-0s, the Nord engine's grate was sloped throughout, which may have made the firing a little easier.

 

From 4-6-2 to 4-8-0 the french way

Chipalong by Hermod posted Feb 10, 2024 at 2:27 PM

 

Its probably old news and obvious to most of you, but I've been doing a bunch of thinking about the design of the Great Bear, and thus other large engines, and on thing that's struck me is how very very different boilers for wide boxes and narrow fireboxes really are. It influences everything from the actual barrel length onwards, especially if large driving wheels come into the picture. A boiler from a wide box 4--6-2 simply won't work on any kind of 4-8-0, and even putting a longer box on the same barrel doesn't really add up. I came across the same thing when I was trying to imagine a 20thC Churchward broad gauge locomotive for one of my fictional locomotive sketches. In that case, given the room between the frames for a pretty wide grate just about everything changes, and I gave up trying to come up with something credible.

 

Riddles' team almost managed to fit the Britannia boiler onto the 9F, but not quite.
Looking at another aspect of wide versus narrow fireboxes: how does the fireman's work compare? Feeding a large grate evidently requires physical strength and stamina as well as skill, but how do those compare between wide (and therefore short) and narrow (and therefore long)?

 

The prime advantage of a wide firebox is that it is shorter than an equivalent long one. There is a limit to how far a fireman can throw coal and the longer the box, the higher the person (and fire hole and footplate) has to be for the fireman to reach the front. Sloping fireboxes can help in this but there’s still a need to reach the front with the swing of the shovel. As power output is essentially related to grate area if you want high power you need to go wide. Or use mechanical stokers.

 

Even "Piccolo" Pete Johnson had to be shown how to get coal into the back corners of a Duchess firebox.

 

It's certainly a different technique, requiring skill rather than strength and usually requires the fireman to wear thick gloves to protect his hand from the heat. I once had a trip on a Danish loco and was impressed by the provision of two firehole doors, one on either side of the firebox. It made firing so much easier and my immediate thought was why wasn't this done in the UK.

 

https://www.jernbanen.dk/damp_solo.php?s=1&lokid=885

WP_20240210_013[1] by Hermod posted Feb 10, 2024 at 8:56 PM

 

OK, that's great news, but....
Is it too much to ask these railways to be prepared should the 0.1% not go to plan?

 

The Chapelon 4-8-0s were unusual in being for express passenger work. The majority of 4-8-0 designs were mixed-traffic or freight designs with smaller coupled wheels. Some had wide fireboxes above the rear wheels, including the Hungarian Class 424, which was probably the most numerous example of a 4-8-0 (Over 500 built). The Hungarian loading gauge was sufficiently high to allow 5ft 3in coupled wheels under a wide firebox, with room to spare.

https://en.wikipedia.org/wiki/MÁV_Class_424
http://www.railfaneurope.net/pix/hu/steam/424/009/P19692.jpg

 

This argument is going on on a facebook group for unbuilt locos...

Given the French emphasis on careful coal use and the (AIUI) poor quality coal, how did they make that 4-8-0 work in practice? Was it just big enough to not clog its ash pan in the runs it did? Did they just pick the ten moat accurate coal-throwers in all France to fire it?

 

The first 12 converted from 4-6-2 were fired by hand.
Fireman mr Marty fired unassisted 4000kg in an hour out on line with three counterpressure locomotives behind at speeds up to 100km/hour.
The normal accepted limit was 3000 lbs/hour in UK.
The next 25 were newbuilts and had licence-built stokers.
To day it would be easy to use clean ,low ash, wood dust.
In Germany it was done on quite some locomotives with lignite dust that was not quite so clean.
Power and reliability was very good.

 

What would that preparation look like?

 

At a rough guess a press release on the lines of "Due to unforseen circumstances 6880 will not be appearing at our event".

 

Only the first 12 Chapelon 4-8-0s (240A) were hand-fired. The later 25 240Ps had mechanical stokers. Of course, stokers were more extravagant in their use of coal but they could increase substantially the boiler evaporation rate and the weight behind the tender by as much as 25%. The coal had to be cut down to suit the stoker which could lead to cinders being expelled from the chimney. Chapelon increased the length of the brick arch to minimise this. The consumption of the 240Ps was about 10% more than the 240As, accounted for by the stoker. The 240Ps were capable of a sustained 3600dbhp on the level.

The 25 240Ps were not newly built, they were rebuilds of the 4500 Pacifics, just like the 240As.

 

I stand corrected.
But they looked much newer and smarter
With 16.5 inch diameter outside high pressure cylinders they could have been made to pass on many UK mainlines