168 Class (J3)
The next engines put upon the line were a number of six-coupled goods locomotives of considerable size and power. Thirty of these were delivered in the years 1851 and 1852 by Messrs. E. B. Wilson & Co., with the G.N.R. Nos. 168 to 197, and ten during 1852 and 1853 by Messrs. W. Fairbairn & Sons, with the Nos. 198, 199 and 300 to 307. The accompanying illustration, Fig. 16, which shows No. 168, will give an idea of the leading external characteristics of Messrs. Wilson’s engines, which were, indeed, of a type that was subsequently adopted to a large extent by different railway companies.
With six-coupled wheels having a diameter of 5-ft., cylinders measuring 16-in. in diameter with a stroke of 24-in., and a total adhesive weight of 29 1/2 tons, it will be seen that this class of goods locomotive was exceptionally powerful for the period at which it first made its appearance. The three pairs of wheels were equally divided over a total wheel-base of 15-ft. 6-in., and all had outside bearings in frames measuring 23-ft. 9-in. over the buffer beams, these frames being of the “sandwich” pattern with a centre of sapling ash 10-in. deep by 3 5/8-in. broad, having on each side an iron plate 7/16-in. thick. In addition, the crank axle had two inside bearings between the wheels, in two iron frame-plates which extended from the cylinders to the firebox.
A peculiarity about the boiler consisted in the adoption of a slightly oval section, the barrel having a vertical diameter of 4-ft. 3-in., while the horizontal diameter was only 4-ft. 1-in. Inside this barrel were 187 tubes of 2-in. diameter and 10-ft. 9 3/16-in. in length between the tube plates. The firebox casing, which was of the raised pattern, had an outside length of 5-ft. 2-in., and a width of 4-ft. 3-in., while the copper firebox itself, which was provided with a transverse mid-feather, measured in its two divisions respectively a length of 2-ft. 0 1/4-in. each, with a common width of 3-ft. 7-in., and a uniform height of 5-ft. 2-in. above the grate bars, all inside measurements. This firebox had a grate area of 14.5 sq. ft. The engines of this class weighed 26 1/2 tons empty, and 29 1/2 tons in working order, the weight being distributed as follows: leading wheels 10 1/2 tons, driving wheels 11 1/2 tons, and trailing wheels 7 1/2 tons.
In Fig. 17 is shown the general design of No. 198, which was one of the ten locomotives of the class built by Messrs. Wm. Fairbairn & Sons. Apparently these differed slightly from the earlier engines of the type, not only in general appearance, but also in some dimensions. For example, the boiler barrel seems to have been of a circular section 10-ft. 7-in. in length, with a diameter of 4-ft. 4-in., and contained only 184 tubes.
The firebox had internal measurements of 4-ft. 6-in. in length by 3-ft. 10 1/2-in. in breadth, with a grate area of 15 sq. ft., and the heating surface formed a total of 1,109-3 sq. ft., of which the firebox accounted for 116-3 sq. ft., and the tubes for the remaining 993 sq. ft. While the total wheel-base remained the same as in the Wilson engines, it was unequally divided, the driving axle being i-in. in advance of the central position, thus giving divisions of 7-ft. 8-in. and 7-ft, 10-in. between the leading and driving, and driving and trailing wheels respectively. The total weight of the engine is given as 30 tons II cwt., and the capacity of the tender tank 1,400 gallons of water.
308 Class (J1)
Within a very short space of time orders were given for a further twenty goods locomotives of the same general design, but with wheels 5-ft. 3-in. in diameter, and cylinders measuring 16 1/2-in. by 24-in., and slightly larger dimensions throughout. Of these, Nos. 308 to 317 were built by Messrs. R. Stephenson & Co. in 1851 and 1852, and Nos. 318 to 327 by Messrs. Nasmyth & Co. in 1852 and 1853 (builders’ Nos. 100 to 109).
