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England’s First 4-6-0

The Story of G.W.R. No. 36


England's first 4-6-0 locomotive - GWR No. 36

ENGLAND'S FIRST 4-6-0 locomotive - G.W.R. No. 36

This engine was not the first 4-6-0 in the British Isles; that distinction belongs to the celebrated “Jones Goods” of the Highland Railway, the first of which, No. 103, is preserved. She was built in 1894, the first of a class of 15. G.W.R. No. 36 was a solitary specimen, the only one of her class; she was completed at Swindon in August, 1896, and was the first 4-6-0 to run in England. Her life was a very short one, because she was really an experimental machine, the first of a series of attempts to produce an engine which would be capable, on its own, of hauling heavy mineral trains from South Wales, through the Severn Tunnel, to Swindon sidings, in less time than was needed by two engines then usually employed, per train, on that line. No. 36 proved to be thoroughly capable of doing all that was expected of her, but Swindon persisted in experimenting for a few years until the even more remarkable 2-6-0 “Aberdares” were evolved and eventually standardised.

Broadly speaking, No. 36 was basically a much enlarged “Duke” class 4-4-0 with six, instead of four coupled wheels, With the exception of the firebox, all the usual Dean features were present, and readily recognisable; but the firebox was a novelty in that its sides were straight and vertical and its grate was a wide one, the width being 5 ft 10 in., far too wide to pass down between the inside frames. The latter, therefore, stopped short in front of the firebox, to which they were attached by means of angle-brackets, but they extended forwards from there right up to the front bufferbeam, in the normal way. The outside frames were, as usual, cut away at the leading end so as to accommodate the curious little bogie with its 5 ft 6 in. wheelbase and Mansell coach wheels.

The boiler was quite a large one, pitched 7 ft 8¾ in. above rail level and made in two rings, the diameters of which were 4 ft 6 in. and 4 ft 7 in. outside; the diameter outside the clothing plates was 4 ft 10½ in. The distance across the firebox clothing plates, at the boiler centre line, was about 6 ft 6 in.; the top of the casing was semi-circular and raised about 6 in. above the top line of the boiler barrel. A very large brass dome was mounted on the back ring of the boiler.

The barrel was 14 ft long and contained 150 Serve tubes 2½ in. in diameter; these were special tubes, much favoured by William Dean at that time, because their insides incorporated a number of ribs which were supposed to extract more heat from the firebox gases and so enhance the heating surface. They did that all right, but in due time they developed other and less desirable habits that were not calculated to add to their usefulness or popularity. They were exceedingly stiff and rigid and, under the effects of alternate expansion and contraction, their movements were apt to get well out of phase with similar action in other parts of the boiler. The result was that they were inclined to play old Harry with the tubeplates, an effect that seriously curtailed the life of the boiler. Because of this, Dean finally confessed himself beaten and gave up using Serve tubes.

The heating surface of No. 36 was 1,517.89 sq. ft, made up of 1402.06 sq. ft for the tubes and 115.83 sq. ft for the firebox. The grate area was 30.5 sq. ft and the working pressure 165 p.s.i. The wheelbase was 25 ft divided into 5 ft 6 in. plus 4 ft 10 in. plus 6 ft 8 in. plus 8 ft, while the wheel diameters were, bogie 2 ft 8 in., and coupled 4 ft 71 in. The overhang at the front was 2 ft, and at the back 6 ft.

The engine weighed 59 tons 10 cwt in working order, 12 tons 6 cwt resting on the bogie, 15 tons 12 cwt on the first coupled axle, 16 tons 11 cwt on the driving axle and 15 tons 1 cwt on the trailing axle.

The bogie was of interest because it was of swing-link type and, unlike the usual Dean bogie, it was double-framed instead of having outside frames only. It appears to have been similar to the bogies of the 0-4-4T engines, and quite different from those fitted to the 4-2-2 and 4-4-0 engines. The cylinders were 20 in. by 24 in.

No. 36 was known as “The Crocodile”, possibly because her large size, small wheels and outside coupling-rods so close to the ground irresistibly suggested crawling when she was moving; the effect was probably intensified by the fact that she normally ran at slow speed.

No. 36’s sphere of operation was confined to territory west of Swindon. She must have been quite an impressive sight. She was finished in all the usual G.W.R. finery of the period, dark green for the boiler, cab and tender body and deep, rich Indian red for frames, splashers and wheels, all except the wheels with the usual black and orangey-yellow lining. Her boiler bands were double-lined, her chimney cap polished copper, while her dome, safety-valve casing and cab-window frames were polished brass; the wheel tyres were black.

The official particulars give the tender capacity as 2,600 gallons; but the tender looks exactly like the standard 2,500 gallon type, judging by photographs. Possibly, there was an additional tank, or well, under the body, to augment the water capacity by 100 gallons. In any case, it was among the earliest G.W.R. tenders to be fitted with water pick-up apparatus, which was shown in the diagram published in 1897. The wheelbase was 13 ft, equally divided, and the diameter of the wheels was 4 ft 1J in. The weight was 33 tons 10 cwt.

When first built this engine was fitted with pumps, driven from the crossheads, for feeding the boiler, and had massive clackboxes with their very conspicuous copper piping, mounted at the sides of the boiler barrel, just behind the smokebox. After a few months, this arrangement was altered, the pumps being replaced by steam and exhaust injectors and the clacks removed to positions on the back of the firebox inside the cab. The holes in the boiler barrel were plugged, and those in the outer clothing were covered by neat brass caps as shown in my drawing.

No. 36 was the first G.W.R. 4-6-0 to come into the Swindon weight diagram system and was allotted “. Diagram 4-6-OA”. From this it is interesting to note that the Whyte system of designation by wheel arrangement was apparently in use at Swindon nearly ten years before it was adopted generally in this country.

The design of this engine was not adopted as standard, and the engine was withdrawn for scrapping in December, 1905, after a life of eight years, during which she ran some 171,430 miles. Her total length, over buffers, was 57 ft 10¾ in. — quite a monster for her time. The grate was 5 ft 10 in. wide; the width of the footplating was 7 ft 8 in.; the length of front bufferbeams was 7 ft 7 in.; the distance between buffer centres was 5 ft 9 in., and the outside frames, usually ¾ in. thick, were generally 6 ft 7 in. apart, inside, while the distance over the treads of footsteps was 8 ft 2¼ in.

       You can read more on “The Coming of the Ten-Wheeler”, “Locomotive Types” and “The Story of the Great Western Railway” on this website.