The 1948 Locomotive Exchanges – The heavy freight classes
The heavy freight classes
In the final part of his examination of the 1948 Locomotive Exchanges, Andrew Wilson looks at the five classes of freight engine involved.
Despite their importance, the heavy freight locomotive exchanges of 1948 have almost become the forgotten part of the testing programme, principally because the trains did not carry the public and so the likes of O S Nock and C J Allen were unable to record the individual performances of the locomotives involved, but freight and goods traffic was still a highly important business sector of the railways in 1948.
Notwithstanding the profitability of the business of moving freight and heavy minerals traffic, exchange trials of the locomotives designed to haul these trains only date back to the Glenfarg tests of June 1917 and January 1921, when the directors of the North British Railway (NBR) were anxious to increase the length of the Fife to Aberdeen coal trains in a bid to reduce operating costs and line occupancy. The 5½ mile-long Glenfarg bank, on the northern flank of the Ochil Hills south of Bridge of Earn on the Perth to Edinburgh (Waverley) line was chosen as the test route and in June 1917 an NBR ‘S’ (LNER ‘J37’) class 0-6-0 was tested along with a North Eastern Railway ‘T2’ (LNER ‘Q6’) class 0-8-0. The results were not conclusive enough to persuade the NBR to adopt an eight-coupled design, although wartime constraints on raw materials may well have influenced the decision. Some 3½ years later another set of comparative trials was arranged over the same route, these being between NBR ‘S’ class 0-6-0 No 46, Great Western Railway Churchward ‘2800’ class 2-8-0 No 2804 and NER Raven ‘T3’ (LNER ‘Q7’) class 0-8-0 No 903. The NBR 0-6-0 took a load of 477 tons up the bank, while No 2804 took 591 tons up, but stalled when the load was increased to
683 tons, albeit in appalling weather conditions. The Raven ‘T3’, however, was able to take 618 tons, 703 tons and 755 tons without stalling. The superiority of the eightcoupled designs was clear to see but the approaching grouping effectively stopped any development work on a North British Railway 0-8-0.
The most up to date classes of heavy freight types were chosen for the 1948 trials; their comparative dimensions are set out in Table One. From the GWR came No 3803, a ‘2884’ class 2-8-0 allocated to Banbury, while the LMS was represented by two Stanier ‘8F’ 2-8-0s, No 48189 of Sheffield’s Grimethorpe shed and No 48400 of Saltley. The Eastern Region selected three Thompson ‘O1’ class 2-8-0s, No 63579 of Sheffield’s Darnall shed, and Nos 63773 and 63789, both of Gorton, while no less than seven WD ‘Austerity’ locomotives were used, three ‘O7’ class 2-8-0s – New England
In the third and concluding part of the Steam Days’ examination of the locomotive exchanges of 1948, Andrew Wilson looks at the testing of five classes of freight engine.
shed’s No 63169, No 63188 of Woodford Halse, and WD No 77000 of Gorton – and four 2-10-0s that were at the time officially stored serviceable; Nos 73774, 73776, 73781 and 73784. The Southern Railway was not represented as its most modern freight class was the Bulleid ‘Q1’ 0-6-0, which was only rated at ‘5F’, while the company’s only eightcoupled class was the Urie ‘G16’ 4-8-0T designed for shunting Feltham hump yard.
Introduced by Charles Collett in 1938, the ‘2884’ class was simply an up-to-date version of the 1903 Churchward ‘2800’ class. Cylinders with outside steam pipes were fitted, along with side-window cabs, short safety valve bonnets, whistle shields, and smokebox door lamp irons. The framing and motion plate were modified, and a fire-iron casing was provided on the fireman’s side alongside the firebox. The Stanier ‘8F’ was broadly based on the Churchward concept but with outside Walschaerts valve gear and a higher degree of superheat. The two ‘Austerity’ classes were in turn an evolution of the Stanier ‘8F’ modified
by Riddles to allow for mass production during World War II. The Thompson ‘O1’, however, was to all intents and purposes his successful ‘B1’ class 4-6-0 design adapted to a 2-8-0 wheel arrangement and using his 100A parallel boiler.
The freight tests were the last of the exchanges to take place, between 26 June and 3 September (see Table Two), and the chosen test routes were quite different from each other, the booked test trains being listed in Table Three. On the Western Region the 119 miles between Acton yard and Severn Tunnel Junction yard was selected. The first 74 miles to Swindon comprised gentle rising gradients in the down direction, which was ideal for examining the constant steaming capacity of the boilers with empty wagon loads in the region of 800 tons. Then follows a 1 in 300 descent to Brinkworth, followed by a 1 in 300 climb to Badminton, before descending at 1 in 300 to Stoke Gifford. Crews were then faced with the 1 in 80/90/68 descent to Pilning, the 1 in 100 down into the Severn Tunnel, and the 1 in 90 climb to Severn Tunnel Junction.
The ex-Midland Railway main line between Brent yard and Toton yard was marginally longer than that between Acton and Severn Tunnel Junction but featured numerous gradients between 1 in 175 and 1 in 200. In addition there were the 1 in 119 (down) and 1 in 120 (up) climbs to Sharnbrook summit, and the 1 in 133 (down) and 1 in 132 (up) ascents to Desborough and Kibworth. Only the 20 miles or so between Leicester and Toton featured moderate gradients of around 1 in 500.
The Southern and Western route between Eastleigh and Bristol via Salisbury, however, was shorter at some 76 miles but had some difficult gradients to contend with considering that the trains were loose coupled behind the dynamometer car. Eastbound out of Westbury was the 1 in 66-76 of Upton Scudamore bank, on which banking assistance was provided for all the preliminary and test trains. Between Milford Junction, Salisbury and Alderbury Junction trains faced a 2¼ mile climb at 1 in 150, while westbound out of Salisbury there was a difficult ¾ mile at 1 in 99.
On the Eastern Region’s chosen 74 mile test route between Ferme Park and New England the steepest gradients facing the trains were 1 in 200 inclines that ranged in length between three and eight miles. On the down journey with empty wagons, the start out of Ferme Park yard was not easy for the cold locomotives as they faced eight miles at 1 in 200 to Potters Bar, while the up workings out of New England had a much easier start before encountering the 1 in 200 of Abbots Ripton bank.
The weights of the up and down trains varied more than on the express and mixed traffic tests due to the nature of loaded and empty wagon workings. On the Western Region, Acton yard despatched trains of 808 tons to Stoke Gifford, although some trains were reduced to 796 tons from Swindon, but only 700 tons were allowed through the Severn Tunnel. In the up direction, 660 tons were permitted between Severn Tunnel Junction and Stoke Gifford yard, where the loads were increased to 1,060-1,108 tons. The load then decreased thanks to dropping wagons off en route until Taplow, from where the reduced load was taken forward to Acton yard.
Between Ferme Park and New England the Eastern Region empty wagon trains were made up to 575 tons. In the up direction, departure from New England saw the loaded trains made up to 980 tons, but by the time wagons had been dropped off, arrival at Ferme Park saw the load down to 964 tons.
On the ex-Midland main line, Brent yard despatched trains weighing 580-600 tons, while the southbound loaded trains from Toton yard were made up to 1,029-1,100 tons. Unlike on the Western and Eastern regions, these loads were worked through without dropping off any loaded wagons. Between Eastleigh and Bristol the loads were set at 426 tons, but in the reverse direction they varied more. Eastbound trains were loaded to around 1,100 tons but at Freshford, between Bath and Trowbridge, this was reduced to between 850 and 949 tons because of Upton Scudamore bank with its 1 in 66-76 gradient and the need for banking assistance.
The control of the freight tests was difficult as the relatively slow-moving trains had to be looped to avoid delaying faster trains. Between Ferme Park and New England six of the ten down trains on the East Coast main line were able to maintain the 200-minute schedule without any out-of-course stops, whereas on the ex-Midland main line delays and permanent way restrictions were so severe that only one of the 16 runs managed to keep the booked time of 340 minutes. On the Western Region the timings were undemanding, with 407 minutes allowed between Acton yard and Severn Tunnel Junction, and 436 minutes booked for the up trips. Between Eastleigh and Bristol the relatively lightly-loaded westbound trains saw most of the trains keep time or run early but on the eastbound train the timekeeping proved to be more problematic due to the gradients and heavier loads.
‘2884’ class
The performance of Churchward/Collett 2-8-0 No 3803 showed a number of unexplained variations and like both the ‘King’ and ‘Modified Hall’, respectively on the express and mixed traffic Locomotive Exchanges, the locomotive did not out perform its rivals on its home region. However, No 3803 gained accolades for the free steaming of its Churchward Standard No 1 boiler and for its overall efficiency, and despite burning hard coal it came a close second to the WD 2-10-0 in the average evaporation rate per pound of coal burnt. It slipped to fourth place in water consumed, and fifth in coal consumed.
No 3803 did well on the Eastern Region and on the joint Southern/Western test, but out-of-course delays on the ex-Midland main line negated the value of the test results.
On the Western Region the freight schedules were not that demanding, the booked time from Acton yard to Severn Tunnel Junction requiring an average speed of only 17½mph; the up allowance was 29 minutes longer, so even slower. As if to expose the slack timings, when working the down empties on 10 August No 3803 managed to gain 82 minutes inclusive of 13 signal or permanent way slacks and one unbooked stop. On the difficult climb out of the Severn Tunnel, where the gradient is 1 in 90 for three miles, No 3803 illustrated the power of Churchward’s 2-8-0s when it was able to exert a steady drawbar pull of 8¼ tons while running at a constant 11½mph. In terms of drawbar horsepower, however, No 3803 was eclipsed by Thompson ‘O1’ class 2-8-0 No 63773.
No 3803 recorded the fastest up run between New England and Ferme Park on 27 August when hauling a 980 ton load, 964 tons from Arlesey, in 188 minutes, at an average speed of 23.7mph inclusive of three slacks and two out-of-course stops. The 35minute early arrival against the booked allowance of 223 minutes was impressive, however it should be noted that on the Eastern Region the freight tests were given the clearest roads. On the previous day’s down run No 3803 recorded its best non-stop time of 184 minutes.
Between Eastleigh and Bristol No 3803 did all that was asked of it, but on the eastbound trains it was not able to keep exact time or run ahead of time – whether this was down to poor locomotive management, outof-course slacks, the loads, gradients or adverse signals is not clear. No 3803 was, however, not alone as ‘8F’ No 48189 and ‘O1’ No 63789 also disappointed in terms of running times.
With the boiler producing ample steam, No 3803 seldom ran with the regulator fully open, with at most three-fifths proving adequate. On the Acton yard to Severn Tunnel Junction test route the cut-off varied between 24% and 34% on the level, with it being lengthened to 39% uphill. As with the ‘Modified Hall’, comment was made of the longitudinal oscillation when running at 30-32mph, a feature of all the two-cylinder Churchward designs with 30in stroke.
Stanier ‘8Fs’
The two Stanier ‘8Fs’, Nos 48189 and 48400, also suffered from inconsistent running and consequent efficiency. On the Eastern Region No 48189 made two highly competent down runs with the empty wagon trains on 17 and 19 August when the 200-minute schedule was cut to 168 minutes and 170 minutes respectively, with average speeds of 26.5mph and 26.2mph. The much heavier loaded up trains were allowed 223 minutes, which the ‘8F’ handled without difficulty.
No 48189 was also used on the Western Region, where it again went about its work capably. Working the up trains on 28 and 30 August with loads of 1,044 tons and 1,065 tons respectively, the 52-minute allowance between Stoke Gifford and Badminton was cut to 38½ minutes and 38 minutes. On the second run, when restarting from Wootton Bassett no less than 11¾ tons was exerted on the drawbar at 5mph.
Moving to the Midland main line, No 48189 was the only one of the freight locomotives to keep time when on 29 June it maintained the 340 minute schedule despite encountering three out-of-course slowings and two unscheduled stops. In contrast, the next day saw classmate No 48400 employed and it managed to lose 114 minutes due to a combination of being in poor mechanical condition and priming badly, and it then took no further part in the tests. Three days later No 48189 lost almost 70 minutes coming up to Brent yard.
For the Eastleigh to Bristol tests No 48189 was used and it followed the pattern set by No 3803 in working the westbound trains to time or better and working the balancing trains back to Eastleigh poorly. On 31 August and 2 September, with fewer delays en route than experienced by the ‘O1’, WDs and ‘2884’ classes, it managed to lose 35 minutes and 38 minutes respectively.
The crews that worked the two ‘8Fs’ did so in markedly different styles. On the Western Region No 48189 was worked with a fixed cut-off set at 30% and with the regulator openings varied as conditions demanded, although full regulator was seldom required – on the steeper banks the cut-off was advanced to 45%. On the Eastern Region the shortest cut-off used was 32% and the maximum 43% but the regulator was rarely more than half open. On the ex-Midland line the badly priming No 48400 was worked with full regulator on both level and uphill sections of line, with cut-offs up to 47%, but on the same route No 48189 was worked with half regulator and the cut-off varied between 18% and 45%. Priming apart, both ‘8Fs’ were able to maintain pressure and water levels with ease, while average evaporation of water in relation to coal burnt put the ‘8Fs’ in third place behind the WD 2-10-0 and No 3803.
Thompson ‘O1’
Like the ‘B1s’ used in the mixed traffic exchanges, the ‘O1’ class 2-8-0s did much to redeem the reputation of Edward Thompson, proving to be fine examples of their genre. Although No 63578 ran at least one of the familiarisation trips, it was Nos 63773 and 63789 that bore the brunt of the test trains. No 63773 was used on the Eastern Region and appears to have been beset by out-of-course delays on both the loaded and empty trains, and as a consequence its best run came on 27 July when New England was reached in 187 minutes despite seven slacks and one unbooked stop.
The same locomotive was used on the Western Region, where the unfortunate No 63773 was the only freight locomotive to lose time on the Acton yard to Severn Tunnel Junction train when confronted by 14 slacks and nine unscheduled stops – the average gain on the booked times on these westbound trains was 55 minutes. However, on Wednesday, 1 September No 63773 produced the best run through the Severn Tunnel with a load of 660 tons. Having accelerated to 36mph at the bottom of the tunnel, the eastbound climb out gradually saw the cut-off lengthened from 25% to 45% and with full regulator the speed did not fall below 17½mph. After Pilning, with the controls unaltered, the ‘O1’ was exerting a pull of 8¼ tons on the drawbar, with the drawbar horsepower rising to 1,142 at 20mph. With the load increased to 1,060 tons at Stoke Gifford yard, No 63773 worked the 11½ miles between Stoke Gifford and Badminton in 35 minutes, cutting 17 minutes from the booked time. When restarting the same train from a signal stop at Wapley Common, no less than 17¼ tons was exerted on a rising gradient of 1 in 300. Later during the test, the same locomotive’s drawbar horsepower was recorded as 1,142 at Hullavington heading west, and it could boast 1,152dhp at Patchway when heading east – this was by far the highest figures for any of the freight locomotives.
On the ex-Midland main line No 63789 suffered from numerous slacks and delays, to the extent that the nearest it came to running to the 340-minute timing was on 23 July when it arrived at Toton in 363 minutes. More typical was the run on 21 July when it arrived 69 minutes late. The best run, two days later, saw No 63789 only slowed by six speed restrictions and four signal stops. No 63789 was also used on the Eastleigh to Bristol runs via Salisbury. Following the pattern set by the other locomotives it did well on the lightlyloaded westbound workings but failed to show its full potential when working the heavier eastbound trains, despite much use of a full regulator.
It appears from the official report that the ‘O1s’ had to be worked harder than the ‘2884’,
‘8F’ and WD classes. There was a significant amount of full regulator running but the boilers steamed well, although on 27 July one of No 63773’s dampers jammed, causing pressure to fall to 113psi and the cut-off advanced to 66%. On the Western Region, pressure was maintained between 210 and 220psi, with 25% cut-off sufficient on the level and 35-45% on the rising gradients. Like the GWR 2-8-0, the ‘O1s’ suffered from considerable lateral oscillation between 22mph and 28mph. In terms of average evaporation rates and coal consumed the Thompson 2-8-0s were only marginally better than the WD 2-8-0s, and below the other locomotives. Although their boiler efficiency was low, this was more than compensated by their modern front end.
WD 2-8-0s and 2-10-0s
The decision to test both the 2-8-0 and 2-10-0 War Department classes was prompted by the fundamental difference between the designs, the use of a narrow firebox on the eightcoupled locomotive and a wide firebox and bigger boiler on the ten-coupled engine. Three 2-8-0s were selected – Nos 63169, 63188 and 77000 – along with No 63188 held spare at Cricklewood, and four 2-10-0s were chosen – Nos 73774, 73776, 73781 and 73784; the latter two were held in reserve in case of any failures.
On the Eastern Region, 2-8-0 No 63169 and 2-10-0 No 73776 were tested, and the 2-10-0 made the best time to New England on 10 August when it arrived in 164 minutes having averaged 27mph despite four unscheduled checks. On its other down run it took 173 minutes but suffered ten signal or permanent way slowings. No 63169 took 169 minutes on 31 August, after experiencing an unbooked signal stop and six permanent way slacks, and 171 minutes on 2 September, inclusive of seven checks. Both WDs are reported to have steamed freely but suffered from pounding between the tender and engine. However, No 73776 did not steam well on 10 and 11 August when pressure fell to 170psi, but by removing the deflector plate the steaming improved.
Nos 63169 and 77000 were also put to work on the Western Region, along with 2-10-0 No 73774. The 2-8-0s again steamed well, maintaining boiler pressure between 195psi and 230psi and having to be fired lightly to avoid excessive blowing off, but
again displayed rough-riding and bumping between the engine and tender.
On 31 August the WD 2-8-0 in use recorded a drawbar horsepower output of 714dhp at 19mph on the 1 in 100 gradient out of the Severn Tunnel with the cut-off set at 45% and the boiler maintaining 215psi. The 2-10-0 posed problems for the Western Region firemen who had no experience of firing a wide firebox and, as a result, tended to over fire and waste steam at the safety valves. Nevertheless, on 20 August No 73774 gained nine minutes between Stoke Gifford and Badminton on the 52-minute allowance. No 77000, which had last been shopped at Swindon Works in July 1948, appears to have been the worst of the WDs for riding, with vertical oscillation and severe bumping as soon as steam was shut off, and then, on 27 August, the engine slipped uncontrollably, resulting in much of the fire disappearing out of the chimney. The increase in coal consumption, coupled with the number of shunting movements required on the up run, emptied the tender and the test had to be concluded at Iver.
Between Brent and Toton 2-10-0 No 73776 was used without the deflector plate and it steamed satisfactorily. Cut-offs varied between 20% and 28% on the level, while the uphill sections saw this increased to between 26% and 47% with the regulator opened no further than half wide. On coasting downhill the regulator was all but closed, with the cut-off increased to 50-60%, which resulted in severe pounding between the engine and tender. This apart, the riding of the engine was good and on 14 July it was recorded as producing a drawbar horsepower of 1,028 on one of the Toton to Brent 1 in 200 inclines, the highest of any of the WD classes. On 14 and 16 July No 73776 lost respectively 151 minutes and 118 minutes on the loaded up workings but, in mitigation, on the first trip there were six signal stops and 14 slacks to contend with, and on the second run there were seven stops and 20 slacks, which again made these test runs of little use.
On the joint Southern/Western region tests, despite its poor riding 2-8-0 No 77000 came nearest to working the eastbound train to time on 10 and 12 August when it recorded times of 238 minutes and 241 minutes against the 233 minute schedule. Wednesday, 25 August saw 2-10-0 No 73774 only lose eight minutes despite encountering five slacks and four signal stops.
Conclusions
The plethora of permanent way restrictions on the test routes handicapped any scientific evaluation of the freight locomotives, and this was also one of the reasons that these locomotives showed some of the most inexplicable variations in performance and efficiency. The larger boiler and firebox on the WD 2-10-0s proved superior to that used on the 2-8-0 variant and this may well have influenced the thinking when the British Railways Standard ‘9F’ 2-10-0s were being designed. That the Churchward 2-8-0 did so well when burning hard coal proved that the oldest design in the exchanges was still one of the best, so it is little wonder that when it became known that a batch of ‘9Fs’ were to be sent to the Western Region the operating officers lobbied hard to build another batch of the ‘2884’ class.