Imaginary Locomotives

[john new]

Good post. Not a dedicated GWR follower, had forgotten them.

 

[rodent279]

46 minutes ago, john new said:

Outside cylinders they used but I don't recall any other outside valve gear* other than on 102 La France and they bought that in.

I stand to be corrected, but I believe there was a broad gauge loco with outside valve gear.

Outside valve gear and inside cylinders was used on some Italian 2-6-0's. Some lasted until the end of steam (early 1970's), and at least one is still active in preservation.

[JimC]

There were even a couple of experimentals back in the 19thC with outside valve gear and inside cylinders.

The 1101s don't really count because they were bought in, but there were also the VOR locomotives.

Edited March 20, 2022 by JimC

[JimC]

2 hours ago, rodent279 said:

Another option to provide valve gear access would be full length side tanks, with a J50 style cutout in the tank.

I considered that, but felt the weight distribution would be wrong. It was done on the rather odd 3901 2-6-2Ts though, which are somewhat congruent to this discussion. The story behind these is said to be that Swindon works was short of machining capacity, so they took some fairly new Dean Goods and crossed them with 45xx, using cylinders, motion components and wheels from the Dean Goods and fitting pony trucks, new frames and cabs and (presumably new) Std 5 boilers.

Edited March 20, 2022 by JimC

[Flying Pig]

1 hour ago, john new said:

Given these are imaginary (experimental) ideas what would it look like with either an early adoption of outside valve gear like the later Hawksworth 15XX pannier tanks or the Stephenson gear outside a-la the LMS built Black V (4)4767? Would outside cylinders and outside v-gear even be an option on a GWR engine? Outside cylinders they used but I don't recall any other outside valve gear* other than on 102 La France and they bought that in.

 

*(Excluding anything inherited in 1923).

 

 

 

Regardless of company culture, fitting outside cylinders ahead of quite large drivers would almost certainly require a leading truck, particularly on a loco intended for passenger work.

[Northmoor]

2 hours ago, JimC said:

There were even a couple of experimentals back in the 19thC with outside valve gear and inside cylinders.

The 1101s don't really count because they were bought in, but there were also the VOR locomotives.

The VoR 2-6-2Ts are outside-cylindered.......

[Hroth]

4 hours ago, JimC said:

There were even a couple of experimentals back in the 19thC with outside valve gear and inside cylinders.

The 1101s don't really count because they were bought in, but there were also the VOR locomotives.

While being "experimental", five LNWR Prince of Wales class locos were converted from inside to outside valve gear (the Tisheys), I suppose to see if it would improve maintenance*. Being Bowen-Cook designs from just before WW1, they were certainly 20th century locomotives!

 

* Having had a quick Google, they were probably modified in the light of problems with the Joy valvegear. As the Joy valvegear was subsequently modified rather than replaced, outside valvegear might have been too expensive a solution!

 

 

Edited March 20, 2022 by Hroth
More info.

[Mike 84C]

Normal oiling of the motion was done from underneath the loco via a pit. Only the oil pots for the valve and piston glands slide bars/crosshead and little ends were easier to fill "over the top". Plus that really foul firemans duty fo tightening the spindle glands or repacking them. I know how b. filthy and awkward it was.

[tythatguy1312]

so for starters, WE'RE BACK BABY
Futurama quotations aside, I'm rather intrigued by the possibility of a 4-8-0 operating on British metals for fast freights. Might've helped the Night Owl's axle loading

[JimC]

4 minutes ago, tythatguy1312 said:

so for starters, WE'RE BACK BABY
Futurama quotations aside, I'm rather intrigued by the possibility of a 4-8-0 operating on British metals for fast freights. Might've helped the Night Owl's axle loading

The 47 had heavyish axle loading,  but no worse than a Castle. AIUI cylinder clearance and minimum curve radius were more restrictive. The first two drivers were quite lightly loaded, it was the last two that approached the limit, so putting a bogie on the front would be of limited value!

[tythatguy1312]

1 minute ago, JimC said:

The 47 had heavyish axle loading,  but no worse than a Castle. AIUI cylinder clearance and minimum curve radius were more restrictive. The first two drivers were quite lightly loaded, it was the last two that approached the limit, so putting a bogie on the front would be of limited value!

in that case, a 2-8-2 or (heaven forbid) a tender 0-8-2 might've been a better solution. For the sake of the Night Owl remaining a fast freight engine I'm leaning more to the former, as the GWR did build a number of 2-8-2T's

[The Johnster]

A 2-8-2 GW tender loco might have convinced Swindon of the value of wide fireboxes, and with the 5’8” driving wheels of the 47xx would certainly have been up to heavy fast freight and all but the fastest passenger jobs, of any weight.  But I doubt Swindon would have ever built such a thing; there was never much work for it and they only needed 10 47xx!

 

In these days, when even the slowest freight trains pop along at 60mph, it is perhaps difficult for those not old enough to remember the ‘traditional’ railway to appreciate the bucolic speed of main line freight trains, nearly all of them part-fitted if fitted at all, ambling between boxes where they would frequently be put into loops or refuge sidings because something faster was closing the gap a few sections to the rear.  Higher speeds were achieved when a bit of a run could be obtained, witness the GC route’s runners and windcutters, and fully fitted express freight was usually tightly timed and didn’t hang about, but these were exceptions.  The general size of driving wheels for heavy freight work (and mineral, another story) was below 5’, and adequate for the work.  

Where higher speeds were needed, driving wheels a foot or so bigger in diameter were needed, and there were plenty of such locos available and capable of the jobs; Halls, Black 5s, B1s, V2s, S15s, and so on.  Locos build specifically for express freight like the 47xx were unusual; the GC’s ‘Fish’ engines come to mind, perhaps the big Gresley GNR moguls, but I’m struggling after that, and it is I reckon significant that no such newly designed engines were built post-grouping.  The trend was for mixed traffic engines, which could manage the express goods and all but the very fastest and heaviest passenger work more economically than something the size of a 47xx, or a 2-8-2 derived from it. 

 

The 72xx has been mentioned, but is a different sort of beast altogether, basically surplus 2-8-0T given extended bunkers to give them the range for double home mineral work so as to get some mileage out of them, not designed from scratch so much as exploiting an opportunity.  Had they not been available Collett would probably have built more 2884s. 
 

 

 

Edited April 1, 2022 by The Johnster

[Mike 84C]

You would not want to go far at anything approaching fast on a 7200t. The in cab din would defeat ear defenders! and the fore & aft motion from the long cylinder stroke would be very uncomfortable. I would think they would have very quickly worn themselves out.

 A 3800, a little better but I'm not sure 60 mph would be very pleasant. One has to remember the condition of yesterday's engines, in the main they were dreadful, worn out.

 I did on one occasion fire an Austerity at about 45 mph, two things I remember from that trip was having to shut off ever time we needed to know how much water was in the boiler and the small coal trying to escape the tender shovel plate, the fore and aft movement was so violent the coal was just shaken out the tender

[Northmoor]

8 hours ago, The Johnster said:

In these days, when even the slowest freight trains pop along at 60mph, it is perhaps difficult for those not old enough to remember the ‘traditional’ railway to appreciate the bucolic speed of main line freight trains, nearly all of them part-fitted if fitted at all, ambling between boxes where they would frequently be put into loops or refuge sidings because something faster was closing the gap a few sections to the rear.  Higher speeds were achieved when a bit of a run could be obtained, witness the GC route’s runners and windcutters, and fully fitted express freight was usually tightly timed and didn’t hang about, but these were exceptions.  The general size of driving wheels for heavy freight work (and mineral, another story) was below 5’, and adequate for the work.  

You're right that this is often forgotten.  ISTR that even up to the end of vac-braked freight in the UK, the maximum speeds were:

75mph for Freightliners

60mph for air-braked traffic (MGRs were 45mph loaded)

45mph for vac-braked freight

25mph(?) for freight with no continuous brake

 

Of course also worth considering in the days of 25mph freights, road freight barely exceeded 30mph either (and if they did, the driver would soon be deaf anyway).

[The Johnster]

Back in Victorian days, freight locos had been broadly divided into 'goods' and 'mineral' types, the difference being the driving wheel size.  'Goods' engines were typically 0-6-0s with driving wheels in the lower 5' diameter ballpark, and were in fact the mixed traffic locos of the day.  'Mineral' locos had smaller driving wheels and were rarely vacuum fitted.  As a very rough generalisation, the 'Goods' were expanded into outside cylinder moguls and, later, 4-6-0s and given given bigger driving wheels so that they could cope with the increased speeds of 20th century passenger work, which turned out to be very handy for parcels jobs and express freight as well.  The 'minerals' morphed into 8-coupled types, either inside cylinder 0-8-0s or outside cylinder 2-8-0s, but, again, the driving wheel size increased into the high 4' range. 

 

In this world, the 47xx are a one off and the low numbers built suggest that the next mixed traffic type down the pecking order, the 43xx, were capable of most express goods work, though the later Halls and Granges were probably better. This is a thread for imaginary locos, and we as enthusiasts tend to prefer bigger and more glamourous engines, and bewail the lack of steam superpower as was common in the US, but the smaller loads rendered this unnecessary, and the British appoach, influenced by this, was usually to build the smallest engine that would do the job in order to save on fuel costs and rely on the crews to drive them properly.  Driving an unfitted or part-fitted goods train over an undulating road was a very highly skilled job, and required a subtle approach from the driver with 'no sudden movements' in order to keep the speed down to a reasonable level, especially when taking up the slack in the coupling in the dips at the bottom of banks before ascending the next one! 

[The Johnster]

Close, but no biscuit:- 

 

.Class 4 freight trains, Freightliner, bogie Carflats, and Cartics, were allowed 75mph, and were of course fully fitted and air braked.

 

.Class 6 were fully fitted with either air or vacuum brakes, and after 1969 did not need a guard's brake van (he rode in the loco's back cab).  The speed depended on the stock, so that for example a train of air braked TEA bogie tanks could run at 60mph, as could vacuum 45tonners, while a train of vacuum fitted vanfits and opens was restricted by the wagon wheelbase to 45mph.  Vacuum fitted bogie bolster E were allowed to run at 60mph.  The speed dependend on the wagon, not the brake.

 

.Class 7 and 8 part-fitted trains were similarly speed restricted by the wagons, though the fitted part of the train was almost always vacuum braked.  The difference is in the 'brake force' (expressed in tons), less for a given load with Class 8 than 7, and the booked point-to-point timings in the WTT.  In general, Class 7 was timed to run at 45mph and Class 8 at 35mph, but the actual speeds the trains could run at depended on the wagons; I used to work a Class 8 bogie bolster train that was allowed 60mph, the maximum allowed for the wagons and the brake van (these could run at up to 60mph, or 75mph in the case of the Southern's Queen Marys).  But the majority of these trains had 10' wheelbase vacuum fitted wagons and 9' wheelbase unfitted minerals, and were speed restricted to 45mph. 

 

 

In all cases except Class 4, all instanter couplings had to be in the 'short' position.  The brake vans were, by my time on the railway in the 70s, 'interesting' in terms of ride quality even at the lower speeds.  Wagon speed restictions were mostly as above, but the MGR hoppers were restricted to 55 mph, and short wheelbase iron ore 35tonner hoppers to 35mph.  I had little to do with twin bolster sets, but IIRC these were speed restricted to 25mph, and the long wheelbase vacuum bolster wagons used to carry loads of continuously welded rail to 20mph loaded; I worked one of these on one occasion and the sight of the load flexing through junctions and curvatrue was enough to convince me that that speed was plenty fast enough, an amazing thing to watch from a brake van!  These were fully fitted Class 6 vacuum braked trains, run under special regulations outlined in the General Appendix.  Another anomaly was the 6-wheeled Miltas, which were allowed 45mph empty but 55mph loaded.  These were screw coupling vacuum fitted vehicles that ran in NPCCS trains if they were loaded and could run in freight trains when they were empty.

 

Prior to the introduction of the numerical train classification system with the 4-character headcodes in the early 60s, the alpha based system was used, and like the numerical system had a somewhat tenuous relationship with the actual train speeds.  Completely unfitted trains, minerals, trip work, or branch pickups were Class J or K, and ran like Class 9s at 25 mph tops with the instanters in the 'long' position to facilitate shunting with poles.  The older 3-link chain couplings were very uncommon after the final demise of XPO wooden minerals in the mid 60s, and must have been banned from all but Class J/K/9 work at some time, but I am not aware of it.  Apart from that, the trains were timed for their Class, but could in theory run up to 60mph if the loco could pull them that fast and then stop them when required.  Any idiot can go fast, it's stopping that sorts out the men from the boys...

 

For modelling purposes, your speeds are good enough for most situations, however.  Branch work with pickups and minerals takes place at 25mph, and shunting is normally done at a 15mph maximum, though yard work on a pickup will be slower than that as the guard needs to walk between changing points and uncoupling wagons, and any movement into roads where men may be unloading or loading vehicles must be undertaken with extreme caution, especially where the drivers' sightlines to the action are compromised such as propelling into goods sheds or other buildings.

[john new]

13 hours ago, The Johnster said:

A 2-8-2 GW tender loco might have convinced Swindon of the value of wide fireboxes, and with the 5’8” driving wheels of the 47xx would certainly have been up to heavy fast freight and all but the fastest passenger jobs, of any weight.  But I doubt Swindon would have ever built such a thing; there was never much work for it and they only needed 10 47xx!

 

In these days, when even the slowest freight trains pop along at 60mph, it is perhaps difficult for those not old enough to remember the ‘traditional’ railway to appreciate the bucolic speed of main line freight trains, nearly all of them part-fitted if fitted at all, ambling between boxes where they would frequently be put into loops or refuge sidings because something faster was closing the gap a few sections to the rear.  Higher speeds were achieved when a bit of a run could be obtained, witness the GC route’s runners and windcutters, and fully fitted express freight was usually tightly timed and didn’t hang about, but these were exceptions.  The general size of driving wheels for heavy freight work (and mineral, another story) was below 5’, and adequate for the work.  

Where higher speeds were needed, driving wheels a foot or so bigger in diameter were needed, and there were plenty of such locos available and capable of the jobs; Halls, Black 5s, B1s, V2s, S15s, and so on.  Locos build specifically for express freight like the 47xx were unusual; the GC’s ‘Fish’ engines come to mind, perhaps the big Gresley GNR moguls, but I’m struggling after that, and it is I reckon significant that no such newly designed engines were built post-grouping.  The trend was for mixed traffic engines, which could manage the express goods and all but the very fastest and heaviest passenger work more economically than something the size of a 47xx, or a 2-8-2 derived from it. 

 

The 72xx has been mentioned, but is a different sort of beast altogether, basically surplus 2-8-0T given extended bunkers to give them the range for double home mineral work so as to get some mileage out of them, not designed from scratch so much as exploiting an opportunity.  Had they not been available Collett would probably have built more 2884s. 
 

 

 

A GWR style 2-8-8-4 would have been something to see!

[The Johnster]

For sure, but what work would it have done?  60 wagon lengths, the size of trains on the GW (except for the Severn Tunnel-Acton 100 wagon coal trains and the 90 wagon transfer freights between STJ and yards down as far as Cardiff Tidal/Marshalling, both of which needed special signalling arrangements), even loaded, would not be a load that such a loco could economically haul; even the 47xx were arguably too big for the work available for them which could be done just as well by Halls when they were built a decade later, using less coal and water.  it is better to have an engine that is too big than one that is too small (unless you're the Midland), but only to a point, after which the coal consumption, perhaps further increased by having to use mechanical stokers, renders it unviable.

 

4700 was originally designed as a faster version of the 28xx, and used the same standard no.1 boiler, but it was found that this was inadequate to supply the cylinders with sufficient steam over long periods, so the larger boiler was designed to address this issue, successfully but at the cost of a limited route availability.  There was not considered to be work for more than 10 of these re-boilered 47xx, never mind a 2-8-8-4!

 

Are you confusing the 2884 class, the updated Collett version of the 28xx with the side window cab and continuous splasher, sometimes incorrectly described as the 38xx, with a possible big articulated Mallett?

[tythatguy1312]

I’m inclined to doubt the GWR would need anything bigger than a 4-6-2 for anything short of banking (even then that’s dictated by axle loads) but even then a large mallet would be fun to see, especially as the type was surprisingly unpopular in the UK on longer narrow gauge lines

[JimC]

6 hours ago, The Johnster said:

4700 was originally designed as a faster version of the 28xx, and used the same standard no.1 boiler [snip] .  There was not considered to be work for more than 10 of these re-boilered 47xx, never mind a 2-8-8-4!

There's more than one version of the genesis of the 47s. Another one is that the 43s could run short of steam on faster timed freights - with only a Std 4 boiler to feed 18x30 cylinders perhaps unsurprising - and so the 47 was an enlarged 43. Also some good sources state that the 47 was always planned with a larger boiler, but the design wasn't finished in time so the Std 1 was a stopgap. Cook also tells us more 47s were asked for, but Collett elected to build Castles instead. 

 

On 47 boiler delays, I note the studies for Std 7 boiler 4-6-0s, and wonder if they tried and failed to get a boiler down to weight for the Star chassis and that was the delay? Almost zero evidence for that speculation though. Under Collett they opted to make a smaller diameter barrel for the upboilered 4-6-0. If Churchward had done that rather than stick with the Great Bears boiler barrel tooling maybe the 47 would have had a Castle sized boiler? 

[JimC]

1 hour ago, tythatguy1312 said:

) but even then a large mallet would be fun to see, 

Very challenging to get one in the loading gauge and weight restrictions though. 

[JimC]

On a completely different topic, I'm not inclined to go back and replace missing images in this thread. I take the view they are mostly 'of the moment' and in any case I post the ones that enthuse me on my Web page (link in sig). Also I haven't kept all of them. Anyone disagree? 

[rockershovel]

Since someone mentioned a 4-8-0, I seem to recall that the Americans experimented with them but gave them up on favour of 4-8-2, 2-8-2 and 2-8-4 types

[john new]

14 hours ago, The Johnster said:

..... snip ----

 

There was not considered to be work for more than 10 of these re-boilered 47xx, never mind a 2-8-8-4!

 

Are you confusing the 2884 class, the updated Collett version of the 28xx with the side window cab and continuous splasher, sometimes incorrectly described as the 38xx, with a possible big articulated Mallett?

An attempt at humour (Obviously it failed).

[rodent279]

19 minutes ago, john new said:

An attempt at humour (Obviously it failed).

Come on, you know you want to....someone photoshop a 28xx elongated into a 2-8-8-4.....you know it makes sense.....😀