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radeng
6th Oct 2016, 23:00
Anyone know what caused Princess Elizabeth, 6202, (it was in LMS livery on the down run to Gloucester)to fail at Gloucester on Oct 5 after working the steam special from Willesden?

4mastacker
7th Oct 2016, 07:47
According to the Facebook page "a fault was found with the blower valve whilst being checked over and serviced for the return leg. This meant that the locomotive couldn't take the train back to London from Gloucester as planned. However, plans for the repair are already underway and Lizzie will then resume her mainline duties later this month."

B Fraser
7th Oct 2016, 10:59
The blower valve controls a jet of steam that exits from around the top of the blastpipe or the base of the chimney to induce a vacuum in the smokebox. This ensures that the firebox gases keep moving in the right direction. In practice, the fireman may use it while stationary to increase the draw on the fire. When on the move, the driver will open the valve when closing the regulator to avoid what is known as "blowback". If the regulator is closed, the exhaust steam will stop drawing the fire. Without the use of the blower, there is a risk that the cab will suddenly become a rather unpleasant place to be. It's a horrible way to die hence the loco was failed.

criticalmass
8th Oct 2016, 05:50
Oops, double-post...now read on...

criticalmass
8th Oct 2016, 05:58
Been doing a bit of reading up on steam locomotives lately, and the blower is a very necessary piece of kit. No self-respecting steam locomotive of any consequence leaves the shed without one. Frequently used when entering a tunnel at speed to preven the sudden conpression of the air forcing the fire up off the grate and ejecting it via the firebox-doors into the cab - the greatly-dreaded "blowback".

I'm guessing a repair to the blower-valve will require the boiler to be blown-down so there is no steam-pressure, then the problem can be fixedwith a new valve, or a repair to the existing one (not sure how many spare blower-valves for a Princess Royal class locomotive would be lying around in their old LMS stores packaging). This is one of the "Lizzies", a 4-cylinder design by Sir William Stanier, if I am not mistaken?

criticalmass
8th Oct 2016, 06:07
Question for the steam locomotive knowledgeables - I know a two-cylinder loco gives four chuffs per revolution of the driving-wheels, and a three-cylinder loco (Duke Of Gloucester, Merchant Navy Class etc) gives six, but does a 4-cylinder loco give eight chuffs or just four? I'm assuming four, because cylinders would work in pairs, or were they offset to give smoother delivery of power?

B Fraser
8th Oct 2016, 08:26
No self-respecting steam locomotive of any consequence leaves the shed without one.


It's a difficult job to raise steam without one, let alone move off shed. Yep, tunnels are a hazard so a blower is essential. There are parts of the line that I fire on where the wind can curl over the top of a bank and the blower is required to safeguard against a blowback.


A 4 cylinder loco gives 8 beats per revolution.

Stanwell
8th Oct 2016, 08:31
And then..

If you're dealing with a Garratt (eg, NSWGR AD60 class) you'd have random offset between front and rear, due to occasional wheelslip .
Makes for interesting listening.

radeng
8th Oct 2016, 11:18
A 4 cylinder loco gives 8 beats per revolution.

Depends on the crank settings between inside and outside cranks. See 'Locomotive Adventure' Vol 1 by Holcroft.

jimtherev
8th Oct 2016, 22:00
<anorak mode> And Lord Howe - a Lord Nelson class loco of the Southern - had its cranks set at 135 degrees, so deffo had 8 beats per rev. Was said to even the pull at the drawbar and stop the wheels slipping on starting. Unfortunately it also lessened the draught on the fire so that the blower had to be on continuously - which wasted steam. Oliver Bulleid, the Southern's Chief Mech Eng, was a genius but loved to play with things which worked ok to start with. So hardly any of the Lord Nelsons were identical with any other, and the locomen hated them, 'cos they couldn't get them to work properly. Pity, they started out as reliable, strong engines. </anorak>

dixi188
9th Oct 2016, 04:51
Surely 6201 is Princess Elizabeth.
6202 was the Turbomotive.

criticalmass
9th Oct 2016, 10:57
dixi188 is right, 6201 is "Princess Elizabeth", and 6202 was the "Turbomotive", not very successful, which was rebuilt as a conventional steam loco in 1952 ("Princess Anne") and written off after the Harrow & Weakldstone railway accident. (I wonder how an RB211-powered locomotive would go today?)

The destruction of "Princess Anne" led Robert Riddles to design the British Standard Class 8 loco, a 4-6-2 Pacific-class, the sole example and prototype of which is the 3-cylinder "Duke Of Gloucester", which happily has been preserved.

Errors during building caused the "Duke" to be "shy of steam" due to poor blastpipe design and undersize dampers, mistakes which were corrected during restoration, turning the locomotive into a real performer. The "Duke" is also unusual (but not unique) for the use of British Caprotti poppet-valves instead of the more usual Walschaerts valve-gear, which allows the "Duke" to run happily at a mere 3% cutoff.

Dunno where we'd be without the Interweb to seek out info on these old but mighty bits of engineering. If you're curious, there's quite a bit of stuff on Youtube about the "Duke".

Tankertrashnav
9th Oct 2016, 16:52
Thanks dixi, I'd been wondering about that. I was sure my Triang 00 Princess Elizabeth was 46201. I also remember the gap in my Ian Allen combined volume between 46201 and 46203, explained by the loss of Princess Anne, as explained by criticalmass

mini
9th Oct 2016, 22:17
Is there a "steam locomotives for dummies" or similar I could study? My young son is fascinated, several visits to various establishments have piqued my interest.

For info I trained as a mechanical engineer so I'm fairly ok with push suck squeeze hot cold etc.

Romeo Charlie
9th Oct 2016, 22:34
All of the Lord Nelsons had their cranks set at 135deg, whereas most other 4cyl locos had them set at 90 (GWR King, Castle, LMS Coronation, Lizzie etc).

The main problem with the Nelsons was the long, narrow firebox which meant that only experienced firemen would get the best out of them. This didn't stop Maunsell (the designer) and Bulleid playing about with them to try and 'improve' them though. 860 Lord Hawke had a longer boiler barrel, 865 Sir John Hawkins had the cranks set at 180deg giving 4 beats per revolution, 859 Lord Hood was fitted with smaller wheels, 857 Lord Howe had a longer, round topped boiler, 862 Lord Collingwood had a Kylchap exhaust etc. None of this really worked until Bulleid lined the cylinders and fitted Lemaitre exhausts and wide chimneys. Only then did they finally become the superb machines they were capable of being.

G-CPTN
9th Oct 2016, 22:36
How do steam engines work? | Who invented steam engines? (http://www.explainthatstuff.com/steamengines.html)

jimtherev
10th Oct 2016, 17:35
All of the Lord Nelsons had their cranks set at 135deg, whereas most other 4cyl locos had them set at 90 (GWR King, Castle, LMS Coronation, Lizzie etc)...
Hmmmmmm. A long time since I got me facts so wrong. Should have pulled down a book off the shelf before posting. One must put it down to mis-remembering what I heard from Southern enginemen... or perhaps they themselves were jumping to wrong concs. Never met one who actually enjoyed firing Nelsons, though. As you say, RC, 'twas probably down to inexperience; there weren't enough of them about and they needed a particular technique.

radeng
11th Oct 2016, 09:19
Not being a touch typist, I really ought to read what I've typed before hitting send! Thus getting the number wrong......

According to Holcroft, the GW Running department men managed to convince the Running Superintendent of the Southern that a train was more rapidly accelerated by a series of short tugs from the 180 degree setting. This was tried on number 865 when it needed repairs to the crank axle and found to make little difference to acceleration but increased coal consumption by about 7.5% when worked hard in rough weather or with a heavy load.

Back in 1920, Holcroft had read a paper before the I. Loc. E on 'Four-cylinder Locomotives' in which he advocated using a 135 degree crank setting. A Drummond P14 was changed to this and found to 'lift' coal trains out of Salisbury yard in a way that the 90 degree cranks could not because the eight beats pulled the fire about less. In this case the coal saving was about 10% and about 4% more water was evaporated per pound of coal. This test convinced Maunsell to use a 135 degree setting in the Nelsons.

Holcroft wrote of the Nelsons: 'the Nelsons were perhaps the most reliable, trouble free and economical in many ways of all the Southern locomotives, but in performance I think they could have been better.' Damning with faint praise........

Allan Lupton
11th Oct 2016, 09:41
Like a lot of contributors to this thread, I'm interested but no expert!
For years I have thought I knew that one of the changes Stanier made when drawing on his GWR origins to design the LMS Pacifics was to separate the power strokes of the four cylinders. To achieve that with piston valves requires four sets of valve drive as well as the appropriate crank angles. What is clear to me now is that it isn't as simple as that, but I'm sure I have heard a Stanier Pacific with the rapid beat that the separation gives - probably Duchess of Hamilton going up Saunderton when they were running Marylebone to Stratford-u-A specials in the 1980s.

Stanwell
11th Oct 2016, 11:59
Like you, Allan, I'm fascinated by the amount of theoretical and, indeed, practical knowledge that has come out on this thread.
Keep it up guys - I'll just get out some bacon and crack a couple of eggs on the shovel, shall I?

radeng
12th Oct 2016, 12:07
P. Ransome-Wallis in his book 'The Last Steam Locomotives of British Railways' shows a picture of 6205 'Princess Victoria' with rocking shafts ahead of the cylinder, and the caption states that 'in 1947, this loco was altered to have only two sets of valve gear with rocking shafts to drive the inside valve gear'.

He also states that the Coronation Class (which included the Duchesses and Cities) differed from the first Stanier Pacifics in that 'the inside valves were driven by rocking shafts behind the cylinders and actuated by the outside valve gear'. In the book 'LMS 150', there is a 3/4 view from the rear of 6254 'City of Stoke on Trent' where the rocking shafts behind the valve chest can just be seen.

It becomes an interesting point as to whether the extra weight and friction involved in using 135 degree crank settings is worthwhile at high speed and load. There is also the effect on balancing and hammer blow to take into account.

By all accounts, the Coronations and Duchesses were very much influenced by T. F. Coleman, who became Chief Draughtsman - it was he suggested to Stanier the layout for their cylinders and motion.

Evanelpus
12th Oct 2016, 15:19
so I'm fairly ok with push suck squeeze hot cold etc.

Sorry but I read this and thought I'd transitioned to the story about the Transavia trolley dolly.

dazdaz1
12th Oct 2016, 15:51
I'm not knocking steam, would it be possible to fit a diesel engine to the old girl, push rods working et al no coal required? :confused:

saved on boiler certificates and maintenance.

4mastacker
12th Oct 2016, 17:56
............., would it be possible to fit a diesel engine to the old girl, .............

Oh dear, you'll have the anoraks steam enthusiasts, making life hell for you with that suggestion.

criticalmass
13th Oct 2016, 02:37
Putting a diesel engine inside a steam locomotive would be akin to equipping a fish with hydroplanes, a periscope and a propeller! Just doesn't need it, works just fine as it was originally designed.

radeng
14th Oct 2016, 10:39
Considering how much is spent on maintaining preserved diesels of equivalent power, I doubt there would be any financial saving, while the first cost of doing it would be enormous.

Stanwell
14th Oct 2016, 10:58
HERETIC !
I demand that he be put on the tumbrel, to be then drawn and quartered - before, in everyone's presence, being slowly burnt at the stake.
Oh dear .. is nothing sacred?