Mr. Ivatt’s next contributions to the locomotive stock of the railway consisted of a further supply of the six-coupled goods engines with saddle tanks which had originally been introduced by his predecessor. The new engines, however, presented certain modifications of details, and were heavier, though the chief alterations visible to outside observation consisted in the introduction of a steam dome, and the abolition of the brass column surrounding the Ramsbottom safety valves. Comparatively few of these engines were put in hand at the Doncaster Works, the greater proportion of the total of 52 so built under Mr. Ivatt’s directions being the product of outside firms, as the following list shows :
|Date.||Builders.||Builder’s Nos.||Engine Nos.|
|1897||Neilson & Co.||5095-5099||1211-1215|
|1898-1899||R Stephenson & Co.||2921-2930||1216-1225|
|1899||Sharp, Stewart & Co.||4471-4495||1226-1250|
A peculiar feature of the five engines built by Messrs. Neilson & Co. was that they had no domes, and still retained the safety valve brass column. These engines are shown in the accompanying illustration, Fig. 90, which represents No. 1213. The same features were also preserved in Nos. 111 and 155, built at Doncaster. It is possible that these particular engines were in reality built to the Stirling specifications, though dated so late as 1897. As regards the others, however, they bear unmistakable signs of a later design, as can be seen from Fig. 91, which shows No. 12 18 of the Stephenson set, and is sufficiently indicative of the appearance of all, except for very trifling differences of detail in such matters as the position and shape of the supplementary-step on the running plate, etc.
The leading dimensions of Nos. 1201-1210, 1216-1250 particularly, were as follows: cylinders 18-in. in diameter with a stroke of 26-in., diameter of driving wheels 4-ft. 7 1/2-in.; wheel-base: leading to driving wheels 7-ft. 3-in., driving to trailing wheels 8-ft. 3-in., total 15-ft. 6-in.; length of frame plates 27-ft. 6-in., with an overhang of 5-ft. 11-in. and 6-ft. 1-in. at leading and trailing ends respectively. The boiler was of Mr. Ivatt’s standard pattern, consisting of two telescopic rings each of plate 9/16-in. thick, the smaller of which had an outside diameter of 4-ft. 3 7/8-in., but forming a barrel measuring slightly more than usual, 10-ft. 6-in. The centre of the boiler was pitched at a height of 7-ft. 1-in. above the rail level, and the barrel contained 215 tubes each having an outside diameter 1 3/4-in. The firebox was of the standard dimensions already given in detail in describing Mr. Ivatt’s coupled bogie engine. A total heating surface was provided of 1,164.23 sq. ft., the tubes yielding 1,061.13 sq. ft., and the firebox 103.1 sq. ft., and the grate area measured 17.8 sq. ft.
In full working order these engines weighed 51 tons 14 cwt., distributed as follows: leading wheels 16 tons 7 cwt., driving wheels 18 tons, and trailing wheels 17 tons 17 cwt.