Best & Worst Locos to Drive

The Q Class seemed to be a kind of Southern Derby 4 equivalent. Was it better to fire?

 

I had 4MT 75078 on saturday at the keighley & worth valley. Seemed to perform very well although on 1 departure from keighley it had to set back a bit then start again.

This was due to the fact it pissed it down with torrential rain on & off all day plus it was trying to lift load 6 on a pretty big grade (1 in 30 or there abouts at keighley?) & add on it's a very sharp curve out of keighley. Other than that performed immaculately.

 

One of the most thoughtfully informative posts I've ever read on NatPres. Clone that man now!

 

Agreed always great value.

Apologies for thread drift but that still leaves the question of what they did with 140 Pacifics between 1950 and the Kent Coast electrification in '59. Let's say the 20 Standard 5s replaced the 20 Urie Arthurs. What else did the SR replace? OK a few Drummonds and the B4Xs and H2s and the N15Xs. Yes, no doubt the D1s and L1s and T9s were cascaded down to less demanding work. But I can't help thinking that the availability ratio of the Bulleids must have been poor otherwise they'd have got rid of a lot more Edwardian locos a lot quicker. I'm not complaining, the SR in the 50s was a marvellous place to see ancient relics.

 

I suspect as much as anything they were simply under-boilered. Better drafting no doubt helped, but if you look at the numbers, they have cylinders practically the same as an N class (19"*26", vs 19"*28") and smaller wheels. So they have the potential to use steam at at least equivalent rate when driven flat out. But an N class has a grate area of 25 sq ft and over 1700 sq ft of heating surface, and a Q class only 21.9 sq ft of grate and 1400 sq ft of heating surface, and ultimately all else being equal, on a smaller grate you can burn less coal and boil less water. A Q1 has the same size wheels and cylinders as a Q, but 27sq ft of grate area; just about 1700 sq ft of heating surface and a higher working pressure.

In effect, the poor reputation of the Q class arose when they were put on mainline duties otherwise reserved for Ns, Us, H15s and S15s which was probably always unrealistic. Improvement of the drafting (particularly with the BR Std 4 front end) undoubtedly helped, but ultimately you were never going to get performance that required similar sustained steaming to an N or S15 on a loco with a much smaller grate. They performed very well on secondary duties.

Tom

 

S.C. Townroe observed that the Bulleids (at least in their original state) needed more fitters to maintain them than the Maunsell types but still had poorer availability. He preferred the B.R. Class 5 to the latter from the shed point of view.

It only shows how professionals look at things differently from amateurs!

PH

 

I think this is a common occurrence - locos labelled as disappointing because of performances on duties they were never designed for which were actually fine on duties they were designed for.
Sometimes this was because they looked "bigger" than they really were.
Other examples being some of the non-Swindon 4-cylinder 4-6-0s (Claughton, Lanky Dreadnaught, GC Lord Faringdon), the Midland Compound and 2P, the Clans (6MT version).

 

Re the Maunsell Q class which no doubt James has fired,

An odd design.

Outside admission piston valves with loco links (Stephensons gear) driven by rocker arms reversing the travel. This required a very large suspension offset to equalise the gear, with consequent large die block slip. A most unsatisfactory arrangement, where launch links would have been far superior. This has been discussed in some detail on another forum a few years ago with contributions by UK valve gear expert Don Ashton.

Maunsell wasnt a valve gear man. (The original SECR 'L' class shows this). He didnt need to be a year or so later as he had Pearson and Holcroft (both ex GWR) with him by 1914 at Ashford. Pearson and Holcroft converted Clayton to GWR long travel and long lap valves.

At the time the Q was designed Maunsell and Clayton were both ill, and Holcroft was not then involved in the drawing office stuff. Someone, who has never to my knowledge been identified, came up with a very bad valve gear arrangement.

To top it all, Bulleid scorned the Q class design but used the chassis and odd valve gear without alteration on his Q1. (Which rather casts a bad view of Bulleid so far as his lack of fundamental understanding of the principles of Stephensons valve gear).

I dont think this has been discussed in any detail before on Nat Pres, but apologies for going off topic.

Cheers,
Julian

 

While I don't have much experience in locomotives, I have worked on a ship that had outside admission valves on the steering engine - and that was located in the wheelhouse. They leaked profusely and I find it hard to understand why they are used.

 

Very interested in the Qs and the Q1s. The Qs are always attributed to Maunsell not Bulleid. .

When Bulleid arrived on the Southern the Q had been designed and authorised to be built at a time when there
was major sickness among the top people who were overseeing locomotive construction, all three of them -
Maunsell, Clayton and Holcroft. Bullied's reaction was to cancel the order and this was averted by Clayton explaining
to him that the materials to build them were ordered.

The cylinders have outside admission to the cylinder valves (& and a drain cock to the lower end of the valve chest
apparently identical to the cylinder drains). Was this a redesign Bulleid requested or was it as already planned?
Bullied, as a young man with Bazin and Ivatt's blessing, redraughted a Great Northern Atlantic to Gosse's formulae when the
Atlantics had Richardson's balanced slide valves with a central exhaust directly through the valves and straight to the blast pipe stand,
as you get with outside admission and central exhaust from piston valves. And of course the Merchant Navies were undoubtably to have
outside admission valves under Bulleid.

The Q1s are always attributed to Bulleid and they certainly don't look like a Mansell locomotive but.... The boiler is the one originally
designed for the Schools class - essentially a reduced version of the Lord Nelson boiler - and if I am right to believe the cylinder block and
valve gear are identical to the Q class they could be said to be Maunsell with a Lemaitre multijet exhaust. Bullied however took
responsibility and from the design of the driving axleboxes there was awareness of the problems that the large modern
0-6-0s & 0-8-0s of the 1920s had had - in particular Gresley's J38 and J39 which were not the wheel arrangement and design first
recommended to the LNER board.

The Qs went fine and the Q1s well indeed.

 

The thing is in engineering, often the flaws in a particular arrangement don't become clear until after a period in service (and often only in service on a particular application). So theoretical advantages often mean something is worth trying, to see if those advantages occur in service.
Just because someone tried something doesn't mean they thought it was an absolute panacea. They just thought it was worth a shot.
Presumably outside admission valves seemed promising in some other application.
Some on NP are very ready to condemn designs (and designers) on the basis of hindsight. Sadly hindsight is not a design tool available to designers.
A loco which can adequately deliver the duties for which it was designed was a succes, whatever enthusiasts might was to criticise a century later.

 

I find it interesting that in the leisured retirement of a heritage railway, some classes with indifferent reputations prior to withdrawal by BR have actually proved very useful amd popular. Tom has enthused about the Wainwright engines on the Bluebell. It's worth remembering that the Ps were not highly regarded, being viewed as inferior to the Terriers from which they were derived, yet match one of them with a suitable load (As the Bluebell often does in the low season) and they do all that is asked of them with no trouble. As I'm red/green colourblind, I could never have followed in my grandfather's footsteps and gone onto the footplate, but I was treated to a one-day Clive Groome driving course when he was based at the Bluebell and 323 was the engine rostered. I must say, albeit based on very limited experience, that I would concur with Tom inasmuch as it seemed pretty straighforward to handle. When the C came into service in the 1970s at SP, some footplate crews said "it's like a big version of a P" clearly meaning this as a compliment

I did volunteer for a short period at the Bluebell in my teens and remember by way of contrast how difficult it was to get the hang of the injectors on the Adams Radial Tank. Perhaps it's a case of me being a slow learner but as an aside, even if it is a difficult engine I'd be very happy to contribute to any future fund to return it to steam.

Another Bluebell engine to have acquitted itself well in preservation is the Q class which has been mentioned above. With the front end modifications, it can handle six bogie coaches with no trouble and is actually an ideal loco for the line. As Tom points out, hooking 12 behind a Q and expecting it to perform like an S15 or a U would inevitably have led to the class acquiring a bad reputation.

Then at the Severn Valley there is the Stanier Mogul which seemed to be well-liked even if (according to an article about the loco and its owning group), the class were none too popular in BR days. No doubt Mr LMS2968 can correct me if the article (and therefore my comments) are wrong. I too have enjoyed his helpful and well-informed insights on LMS engines.

 

The popularity or otherwise of the Stanier Crabs falls between the footplatemen and the enthusiast fraternity. They were certainly unpopular with the latter, and this is at least partly accounted for by their tall chimneys. From head on and at a distance, the average spotter on seeing this would assume that he was about to underline a named engine. a Jubilee, and would often be unconsolable when a humble goods engine eventually lumbered past. Tales from footplatemen are rather more scarce: some were (surprisingly, and also written in retrospect) enthusiastic and, on a goods train, preferred them to a Black Five as they were stronger and had better adhesion. Several firemen complained about them, and generally about the seat, which was the lid of an oil cabinet on his side of the cab, and not the most comfortable of seats. But many men I spoke to in my BR days couldn't remember them and the merged simply into the other Stanier classes, which is something of recommendation in itself. One thing is that they steamed well (as did other Stanier classes with a similar boiler), despite some rumours to the contrary. They did struggle to get past this poor reputation, until 2968 stormed from Settle Junction to Blea Moor on 21st December 1996.

An article appeared in British Railways Illustrated (July 2002) which slated them. This though was from the maintenance point of view by the former shedmaster at Nuneaton, where the run down members of the class congregated towards the ends of their lives. Reading it, it's apparent that many of the criticisms are of features common to all Stanier classes and others; were one-off incidents; and at least in one case defy logic. I don't know what the engines actually did to so upset Messrs Fox and Kinder, but it must have been bad!

 

Hi andrew,

There is nothing wrong per se with outside admission piston valves as Hirn points out above, and all slide valve designs are anyway outside admission. The problem is matching the type of valves with the correct Stephensons valve gear arrangement (loco links or launch links), and depending on whether direct drive or indirect drive. Holcroft knew all about this. The Maunsell Q class has the wrong arrangement! Bulleid used the chassis cylinders and valve gear without alteration for his Q1s, and perpetuated the error.

This is not looking back with hindsight. The principles were well known to the valve gear experts at the time, and in the USA even longer going back to the 1860s.

Loco links require bigger eccentrics and create more friction with long lap long travel valves due to the larger throw required.

If you look at the Q and Q1 and examine the expansion links you will see the considerable suspension offset on the trunnion for the bottom of the lifting links.

Apologies for going off topic again!

Cheerss,
Julian

 

Regarding the outside admission valves on the Q/Q1 , it gives a very short, straight path for steam to leave the cylinders. Indeed with the engine set right, you can see the back of the cylinders on the Q1 from the bottom of the blast pipe.
I found the Q1 a dirty engine to be on but it was very good at turning coal into an accelerating train.
The Q seems nicer. It performs better this time round, it doesn’t pull its fire forward on the grate so much. Some drivers pull it up quite tight. The valve events will never be perfect for reasons stated by others. I was firing it the 80‘s and driving it now.
If you want an interesting footplate experience the North London Tank is quite a challenge.
Lifting injectors (NOOOO!) a screw reverser which indicates the wrong way, firehole doors that glow orange, you have to coal it from inside the cab and balancing that pretty much banned the engine from dining trains. It couldn’t half shift engineer’s trains though.
I really like the U’s to drive and fire. The pull down injector steam valves are nice and used on other Ashford/SR designs.
I’d like to see a thread from a fitter’s point of view but I suspect not so many read Nat Pres.
Ashford products all the way!

Russ.

 

Ah, somebody else remembers the Goss story. I also recall that Bulleid was slightly surprised to find that the results he got from the Goss formulae came out very similar to the standard draughting, and asked how it had been done. The answer came back that Ivatt had the drawing office scheme (based on previous GNR practice) drawn in full scale and put up against the drawing office wall. He then made some tweaks to the taper and sweep, which were faithfully copied and on to 251 they went.

I think the use of outside admission piston valves on both the Q1s and the Pacifics is a coincidence. The Q1 is fairly evidently a super-Q built to minimum cost with limited design time, so anything that was functioning adequately and didn't add significantly to cost, weight or complexity was unlikely to be changed. Adopting the original design Schools boiler (I've never seen that theory before, but it makes a certain amount of sense) was a sensible way of getting good results quickly as well. For the Pacifics, on the other hand, with the valve drive in the between the valve heads, outside admission valves are the logical way of minimising sealing issues.

They also work well with Walschaerts gear, because the combination lever magnifies the valve movement rather than reducing, allowing for a more compact arrangement. Drummond used this on his D15 4-4-0s, to save a couple of eccentrics and allow bigger crank webs and bearings; I have seen the theory that these were in part the inspiration for the Q arrangement, in which case somebody missed half the reasoning behind it when they fitted Stephenson's gear.

 

Hi 8126,

When in his 90s a guy at Eastleigh (sorry forget his name but it was 'Eric' someone) wrote that 50 years earlier he apparently called Maunsell over in the erecting shop and got him to peer down the D15 (I think) blastpipe saying 'you would get a very free exhaust with outside admission piston valves'. Hence apparently the Q arrangement which was non standard and as explained above had the wrong valve gear arrangement. Had the piston valves been inside admission the valve gear arrangement with loco links would have been perfect with rocker arms. It would also have been perfect with outside admission and launch links and rocker arms.

Now, Maunsell visited Eastleigh very rarely (Clayton's job), and the idea of him being called over in his suit and bowler hat to peer down a blast pipe of a Drummond loco to prove a point on design requires a pinch of salt I suggest! Maunsell was all for standardisation, which the Qs were definitely not! And what would have been a very good loco in 1938 was completely mucked up. I am quite sure that Clayton and Maunsell took no part in the design, and definitely Holcroft did not.

Who actually designed the Maunsell Q class, and particularly the defective valve gear arrangement still remains a mystery despite extensive research.

Cheers,
Julian

 

I agree that story doesn't really ring true, since from the GA of the D15 what they would actually have seen was the S-bend in the exhaust introduced when Urie superheated them and had to move the chimney forwards, and maybe the slightest glimpse of steam chest.