Hang on a minute there. The loco ventured up yon-bonnie-banks with the v12 JSV Mirrlees engine which was deemed a failure in all its original guises, and was kicked out for the reliable 12SVT already proven in use in Australia and in the 16 cylinder variant prototypes of the UK in the 40s and 50s. So the Class '30' that never was stenciled on a loco, was the failure not the class 31.
How suitable then would the class 31 have been for the west highland line and if they had been technically suited, why were they then never utilised ?
It is probably pretty arguable that the loco was failed due to poor traction when compared to the class 20, 24 and 26 contemporaries of the late 50s and the 27 and 29 after comers. Also the locomotive at 104 tonnes as a 31 and presumably less as the JSV Vac (vb) predecessor, weighs less than a Black 5 kettle but the arguement about wheel diameter and contact area and tractive effort perhaps persisted until the BRCW and BR type 2s showed their worth or were shoe horned into service.
If you want to call a 31 a pedestrian loco, then you should get hauled by any other type two on the WHL. 27s were occaisionally out in force even in the 37/0's halcyon days when there was some issue which 'grounded' the fleet, if I was informed rightly at the time this was either issues with boilers or issues with tyre wear - HSE siding on ban them all, especially before the rather better maintained welsh and higher number 37/1s came to supplement the good bad and dross split boxes sent from stratford in 1979/1982. You could note straight away that the progress was rather lacsidasical with a 27. It was like being hauled by a 37 which was on its last legs and just on the point of failure. Standing start acceleration was all that beating drum tip topping and not a lot of progress.
True on stretches with speeds of 45/50 mph you could maybe see an advantage as the 27 burls along, as do other 6LDA teacup/rattlers . A speed range much as on the favourite monotomous bash of the jockular vermin's fan base , the dreadfully dull 40/55 mph fife circuit where a 40 or a 37s superior power is capped by bumping in and out of field diversion all the time once out of the frequent stations and out in the bland pastoral landscape with its curiously serpentine route.
Rat and Mac-rat bashers always say that if you had load eight then you could shove a pair of the vermin on the front and hey presto, bye bye syphon and ponderous class 40. But hey, a pair of 37s will once again piss all over them, and managed most of the Aberystwyth diagrams as singles, on arguably better timings than the paired 25s judgin by the festers at the crossing stations with the then newbies in 1985, outperforming the timetable handsomely.
27s and other Mac Rats do have a certain charm in plodding through the spectacular countryside along the precarious shelf/cuttings and through the tunnels and over the viaducts of the West Highland Line, however the road improvements were in place by the late 70s and further work planned threatened to make the route pretty much unviable as a competitive form of transport vs the bus (which is now actually my preffered mode of public trans' to Oban at least since sprintershitation, faster, just as scenic and often a better view in fact and most of all, quieter!!) With private car ownership on the rise too, the WHL needed a boost and that meant more bhp within the RA5 confines
The 37 diagrams were simply a lot faster than the 27s and other type 2s and not only that but all forms of 37s regularily kept well ahead of most of the diagrams with only a few being a bit of a squeeze to the crew change point most often being Arrochar. Usually there was a 'dreadful fester' at Arrochar as the crew had gassed on the faster sections to Glen Douglas to have extra time for tea at arrochar. The same was even true of the 'up' sleeper with its 400 tonnes odd some nights with the lady ETHEL enterage, which if driven a bit gingerly while using the advantage of more powerful air brakes could run well ahead of time and lead to festers in the up tae Glesga direction too.
In fact in my honest opinion of app. 9,000 miles behind class 37/0s and /1s on the route I would say that the 37s were by in large overkill for any loads under 6 mark 1s or ETHEL on five. Drivers in charge of load three to five, took full advantage of the storming acceleration and then let the locos often poodle around in second field opening up to get momentum up to third field in order to get 50/60 mph up on sections which were 40/50 speed limits. The fact that the stalwart 37014 made up almost an hour from Crianlarich to Dumbarton on the ETHEL warmed sleeper with load 6 one night is testimony to both the loco and of course the devil himself, Peter Walker at the stick.
So the class 31 should have maybe had a chance? Similar gearing and some very similar diagramming on terra-flatta in the south and west country seem to point to the 31 being pretty much a type 3. In fact you could easily say that the venerable 31 with its high reliability and simplicity probably delivered 1470 bhp a good deal more often than some of Stratfords poorer heaps which ED depot was landed with, such as 37025, 37081 and 37108 which often seemed to be doing as bad a job as Rottus Caledonia. Boilered, Ra5, with good visibility and a history of snow plough mounting , standard blue star on general examples of the class...so on.
Many have speculated why indeed 31/4s were not simply diverted away to work ETH services on the whl. The firts, the sleeper, went down to load 5 which a ex loco heating unit like a 31/4 coould plod around with at less than 40 mph.
An issue may have been with the gearing, which I do not have a source for the figure of, but the loco was only 15% or so less powerful, so notch 6 of 8 was your comparison in the 'class 30 failure' on the WHL. Certainly you have to understand that a 37 is in its element thrashing up a gradient with a couple of hundred tonnes and then maintaining 30-40mph which is the speed limit on a very large proportion of the line. A 31 pootles up slower and then has an awkward field diversion at 28 mph or so, just when drivers would want to be picking up power to get back up to the speed limit after a tortuous curve or on a minor summit.
The issue here is not actually a straight hypothetical technical comparison. Despite there being both other SVT and RK classes allocated to Eastfield from the 1950s, there was experience with the superior power of the 37s from allocations in the 1960s forward. It must not be overlooked that at the time in the late 1970s the planned aluminium trains from Ft Bill were probably going to be the most torturous of any freight diagram... . comparing to the infamous Llanwern iron ore trains and the 'Gunnie' Cement....both of which of course were under the command of 37s during the 1970s.
The matter is more of allocation and planning of classes> because of course during the 1970s, 31s spread their sphere of allocation as they prove to be more useful on faster or heavier services than 6LDA rodentiae, and were replacing diesel hydraulic services too as locos like Hymeks were phased out.
The success of the 31/4 ( the first ETH ex locomotives as some wags put it) re-purposing lead to the class being an obvious choice for replacing XC DMUs which were frankly completely and utterly knackered by 1980. With the early examples being withdrawn, there was actually no land-grab available whereas stratford were pretty keen to get on with ETHing and standardising on the ubiquitous duff /4 and eventually /5 and /6 as they churned them out with the wee extra orang boxes on each end.
Their 37s had been there almost two decades for some examples, and it meant they could rid themselves of the least reliable locos to general repair and reallocation to ScR and ED in particular. We inherited some right old timers from other depots too, like the vb 37 017 originally ED in its first caledonian guise and the eventually rare to bag 37 028 in its 'vo' guise although I think it was actually 'vi' when I had her to Ft bill on a staking hot summer's day in 1983.
Although 37s for passenger work were new to Eastfield and Inverness, there had been freight allocation to first Grangemouth then eastfield from the 1960s to the 1970s , plus motherwell getting them at some point, so there was some experience and driver knowledge on them. Plus in the late 70s the class 40 came to run most every express out of Queen street, the cab and controls being similar enough to a 37, while the maintainence is not miles apart when it gets down to using bloody big spanners on cylinder heads to big-ends. At one point it was rumoured that ED would become a 10 inch bore shed for all SVT /CSVT / RK engines of SCr, even gaining class 50s to work the Aberdeen expresses, while Haymarket would get all oily over the 12 LDAs and keep the pestolent 6ldas going a few more years after 1982. This rumour must have been based on something because Chris Greene denied it to Jail Enthusiast Rag in his first year in the Throne of ScR.
Anyway we in terra scotia, got intercooled Ruston engines in a nice looking, punchy package the EE type 3, syphon gee. Not all was all that well though. It is a bit strange that by in large the western region 37s reallocated to Scotland inn 1982 onward were in much better condition than the eastern /GN locos from stratford, gateshead and so on barring the latter boilered flock around 37260/262/264. The welshies had had a hard life Boyo, up in the valleys on all from loose fitted to big nasty airbraked lumbering runs of the black burny stone stuff. However them being a squeeze newer and perhaps drivers being trained to respect them , plus seemngly much better maintanence at CD etc, meant that they were on average far superior to the split boxers. East field and St Rollox too soon rolled their sleeves up though and got to work on their engines and boilers, and paint work too. Some went into Doncaster or other BRE main works, others had very good work achieved under the victorian rooves of Inverness's sheds. However this was usually in vain as particular notorious drivers chose to 'notch 8' them at any given chance from a standing start or whenever they were a bit bored and the resulting wheel slip and tyre wear kept the tyring shop at St Rollox and the top o' the bank in business. This coupled to flange and bearing wear, probably caused by drivers abusing speed limits on the Crianlarich/Craigendorran sections, lead to the trials with 'bendy bogies' in fact swingy axles would be a better description. 37/4s were never fitted with them, the lower gearing perhaps curbing some excesses or better driver discipline giving them actually a longer, healthier life than their older bretherin originally transfered north of the border five to six years before their emergence.
I digress into a bit of nostalgia and speculative ranting, so back to the topic>
It would be interesting to shove a 31 /0 up the WHL on similar loads and let a pair work a simulated freight like the aluminium services. Then of course you could put a 31/4 on a load four sleeper no issue, maybe turn off the heat for the bigger banks if the story of them being segregated out of that power is not true that is. 31/4s would no doubt keep to the slower sprinter timetable on a bigger capacity train. Did you actually know, dear syphon basher insect of post 1988 start, that they fudged the outgoing 37/4 timetable with an extra forty minutes or so put on most trains between the penultimate stations and their destinations, mainly noticebly at Dunbarton and upon arriving gleefully early at GSQ, evern with the low level diversion in place????
Anyway, given a different twist in fortunes the Goyle creatures could well have purred and burbled their way over Whistlefield bank and glanced down upon Loch Goil below as the spectacular vista of the Argyll hills and Lochs is suddenly unvelied coming out of the cutting as you pass the Green Kettle. Had they chosen to keep Hymeks, had they scrapped more 6LDAs in the 70s, had they ordered more Goyles, had they never been ETH fitted .....you can go on and on. Technically the 1470 hp goil with a boiler would have been superior to the tinny rodent classes which pagiued the WHL and struggled to better the steam diagrams they were introduced to surpass.
A glorious waste of 1750hp deliverd with gusto then entailed on all trains for just over half a decade and then remarkably outlived any class of locomotive used on the line before them in charge of the 'Ftr Bill ETH Bedz' , and still finding use on PW and schedule tour trains today. How the Glens and Lochs reverberrated to one of English Electrics finest creations, and how we enjoyed sticking our heads oot the windaes to breath a mix of pure highland air and class 37 exaust fumes as we revelled in the experience of the thrash, the beauty of nature and the banter of the railway men and boys back then in the early 1980s.