Nearly at the close of the year 1896 Mr. Ivatt produced from the Doncaster Works his first passenger engine designed for the G. N. R., which was allotted the running No. 400, and in its details marked a new departure so far as this particular line was concerned. In reality, however, this locomotive contained no startling novelties. It was not designed for express traffic, but was merely an improved development of the four-coupled passenger engines already in use, having the same size of driving wheels and cylinders as had been adopted by Mr. Stirling for many years.
Apart from these main characteristics, nevertheless, there was abundant evidence of a change of regime, the principal external indications being the employment of a leading bogie and the presence of a steam dome on the boiler barrel.
As can be seen from the accompanying Fig. 88, No. 400 differed also in external details of lesser importance, changes being made in the shape of the cab, in the driving-wheel splashers and in the position of the sandboxes. This engine had cylinders 17 1/2-in. in diameter with a stroke of 26-in., their distance apart from centre to centre being 2-ft. 4 1/2-in., thus allowing a fairly generous space for the valves to be placed between them. The steam ports measured 14-in. by 1 1/2-in., and the exhaust ports 14-in. by 3 1/2-in.; and the valves had a maximum travel of 41/8-in., with a lead in full gear of 5/32-in. and an outside lap of 4 1/8-in.
In nearly every respect this maiden design has constituted a standard for future reproduction. The bogie, of the swing link type, had four wheels each having a diameter on the tread, when new, of 3-ft. 7 1/2-in., the centres of the two axles being 6-ft. 3-in. apart, with the bogie pin 1 1/2-in. to the rear of the central position, thereby causing two unequal divisions of 3-ft. and 3-ft. 3-in. between the bogie pin and the trailing and leading bogie wheels respectively. The two pairs of coupled wheels, 6-ft. 7 1/2-in. in diameter, had their centres 8-ft. 3-in. apart, and from the driving wheels to the rear pair of bogie wheels there was a distance of 6-ft. 9-in., centre to centre, the total wheel-base of the engine being 21-ft. 3-in. Between buffer beams the frame plates measured 27-ft. 7-in., the overhang being 2-ft. 5-in. in front, or 5-ft. 8-in. reckoned from the bogie pin, and 3-ft. 11-in. at the trailing end.
It will be noted that Mr. Ivatt substituted a steel plate buffer beam at the leading end in place of the “sandwich” beam adopted by his predecessor. Apart from the addition of a steam dome, Mr. Ivatt has modified the design of the boiler by the reduction of the three telescopic rings standardized by Mr. Stirling to two, and the employment of a thicker gauge of plate to stand the increased working pressure of 170 lbs. per sq. in., 9/16-in. in place of 1/2-in. The barrel of the boiler measured 10-ft. 1-in. long, with a diameter outside the smallest ring of 4-ft. 3 7/8-in., and it was pitched with its centre line 7-ft. 5 1/2-in. above the level of the rails. At the leading end was a smokebox having an external length of 2-ft. 10 1/4- in. and provided with a cast-iron chimney of standard G. N. pattern.
The firebox casing had an outside length of 5-ft. 6-in., a maximum external width of 4-ft. 6 1/8-in. at the centre line of the boiler and of 4-ft. 0 1/2-in. at the bottom, and was built throughout of 9/16-in. plate. The firebox itself was of copper and had a length at the top of 4-ft. 9 3/4-in., and at the bottom of 5-ft. 0 1/4-in., a width at the top off 3-ft. 8-in. and at the bottom of 3-ft. 6 3/4-in., and a height in front of 5-ft. 11-in., and at back of 5-ft. 5 3/16-in.. all inside measurements, while the side and back plates were 9/16-in an the tube plate was 3/4-in. in thickness.
Firebox and casing were held together by means of 665 copper stays 7/8-in. in diameter. Within the barrel of the boiler were packed 215 copper tubes 10-ft. 4 3/8-in. long between plates, and 1 3/4-in. in outside diameter, with a thickness of 10 S. W. G. at the firebox end and 12 S. W. G. at the smokebox end. The steam dome had an inside diameter of 2-ft. In the matter of heating surface this engine showed a distinct increase on its predecessors, the total being 1,123.8 sq. ft., of which 103.1 sq. ft. were contributed by the firebox and 1,020.7 sq. ft. by the tubes; the grate area measured 17.8 sq. ft. A total weight in full working order of 44 tons 7 cwt. was distributed as follows: bogie wheels 16 tons 9 cwt., driving wheels 14 tons 9 cwt., and coupled wheels 13 tons 9 cwt.
The tender was of a somewhat modified type, having the tank arranged in horseshoe fashion, and with gauge cocks fitted at the footplate end to show the amount of water at any time remaining in the tank. It was carried on six wheels, each 4-ft. 1 1/2-in. in diameter, equally spaced over a wheel-base of 13-ft. There was a capacity of 3,287 gallons of water and 200 cubic feet of coal, the weight of the tender empty being 18 tons 12 cwt. 2 qrs. and loaded 38 tons 6 cwt. In all, eleven engines were built at Doncaster to this initial design in the following order : —
|Date||Doncaster Nos.||Engine Nos.|
No. 1,080, however, differed from the rest in having a plain cast-iron safety valve cover of the ordinary Ramsbottom pattern in place of the polished brass column adopted throughout by Mr. Stirling.
1301 – 1320
Towards the close of 1897 and the beginning of 1898, a series of coupled passenger engines with leading bogies was brought out. As can be seen from the accompanying illustration. Fig. 92, which shows No. 13 12, these were practically the same as No. 400, already described, except for the introduction of the ordinary iron casing to the Ramsbottom safety valves, which had already been adopted on No. 1080, as previously mentioned.
In dimensions these engines were throughout identical with their prototype, so that a recapitulation of the figures already given is unnecessary here. The numbers of the engines in question were as follows : —
|Date.||Doncaster Nos.||Engine Nos.|
Of these the engines built in 1897 had a brass beading round the driving-wheel splashers, while Nos. 131 1-20 had a black beading. No. 1320 differed from the rest by having the running plate raised at the driving wheels to clear the coupling rods, a detail which has since been adopted on other engines. This engine is illustrated separately in Fig. 93.