K1 – Long Tom Mineral Engines

Immediately following the appearance of the engines last referred to, came a new type of goods locomotive which is deserving of extended mention. From time to time, as this brief history has sought to show, the locomotive superintendents of the Great Northern Railway have produced exceptionally powerful engines for the heavy mineral traffic of the line. Mr. Sturrock led off with his famous steam tender engines, and Mr. Stirling followed suit with the large mineral engines of 1872. In neither instance however, was the general traffic management of the line quite ripe for the introduction of such power, and the two classes severally failed owing to their very success.

Apparently, however, the time is now suitable for a considerable increase in the tractive capacity of mineral engines on the G. N. R., and Mr. Ivatt has responded by designing a type of locomotive for this work which bids fair to meet all requirements in that direction for some years to come.

The accompanying illustration, Fig. 106, shows the pioneer of the type and presents the chief details of its outside appearance. It will be seen at once that No. 401 is of immense tractive and adhesive power, having cylinders 192-in. by 26-in., eight-coupled wheels having, with 3 in. tyres, a diameter of only 4ft. 8-in., and a total weight available for adhesion of more than 54 1/2 tons, while its capacity to raise sufficient steam to supply those big cylinders is evidenced by the ample size of the boiler, which is practically of the same type as that adopted already for the large ten-wheel express engines of the “990” class.

The cylinders, whose dimensions as new are stated above, drive the second pair of wheels, towards which they incline downwards at an angle corresponding to a drop of 4-in. in 2-ft. 2 3/8-in., the distance from centre of cylinders to centre of driving axle being 9-ft. 9-in., and the connecting rods being 5-ft. 7 3/4-in. long between centres. The slide valves are of the balanced kind, on top of the cylinders, deriving their motion from the eccentrics and expansion gear through the medium of a rocking shaft.

The driving wheels, 4-ft. 8-in. in diameter, occupy a total wheel-base of 17-ft. 8-in., of which 5-ft. 8-in. separate the middle pairs, with the leading and trailing axles respectively distant to the extent of 6-ft.

Overall, the frame plates measure 30-ft., the overhang in front being 6-ft. 3-in., and at back 6-ft. 1-in., while the footplate is 1-ft. 2-in. above the rail level.

The boiler barrel, pitched with its centre line 8-ft. 4-in. above the rails, is built up of three rings of 9/16-in. steel, the middle ring having an outside diameter of 4-ft. 6 7/8-in., and the outer rings being 4-ft. 8-in. in diameter outside. The length of the barrel is 14-ft. 8 5/8-in., of which, however, 1-ft. 11 1/4-in. is occupied by the rearward extension of the smokebox.

The smokebox proper has a length of 3-ft. 2 3/8-in. and a diameter of 5-ft. 6 1/2-in., inside measurements. The firebox casing is 8-ft. long outside and 4-ft. 0 1/2-in. wide at the bottom, its depths below the centre line of the boiler being 5-ft. 6-in. in front and 4-ft. 8-in. at back. Within the boiler barrel are 191 tubes 2-in. in diameter and 13-ft. long, the total heating surface being

1438.84 sq. ft., of which the firebox contributes 136.74 sq. ft., and the tubes the remaining 1302.1 sq. ft. The grate area is 24.5 sq. ft. It should be noted that though the Ramsbottom type of safety valve is retained in these big engines, it is duplicated, and the working pressure is fixed at 175 lb. per sq. in.

In full working order this type of engine weighs a total of 54 tons 12 cwt. 1 qr., apportioned as follows: Leading wheels 13 tons 3 cwt. 2 qrs, driving wheels 14 tons 18 cwt. 3 qrs., intermediate wheels 12 tons 18 cwt. 1 qr., and trailing wheels 13 tons 11 cwt. 3 qrs.

The tender is of the standard large type, weighing, with 3,670 gallons of water and 5 tons of coal, to tons 18 cwt. 1 qr.; thus the total weight of engine and tender is 95 tons to cwt. 2 qrs.; and the total length over buffers is 54-ft 71-in.

Following is a list of the eight-coupled mineral engines of the No. 400 class built up to 1906:-

No. 407 and several others were subsequently fitted with a variable blast pipe, which is automatically worked from the reversing rod, and No. 417 has been fitted with the Schmidt superheater and piston valves, in conjunction with which the Klinger forced system of lubricating the cylinders and valves was introduced.

A new series of eight-coupled mineral engines was put in order at Doncaster in 1909. They differed from their prototype, No. 4o1, in having fluted coupling rods and larger crank pins and were fitted with the exhaust steam injector on the left-hand side. They bear the following numbers:-

Nos. 451 to 455 were fitted with the Schmidt super-heater, piston valves and 21-in. cylinders. They also had other features slightly different from those of their predecessors. In order to accommodate the tail rods of the piston valves, the overhang at the leading end was increased by about 9-in., and the centre of the boiler was raised 2-in., to 8-ft. 6-in. The heating surface was as follows: firebox 137 sq. ft., tubes 1,027 sq. ft., total 1,164 sq. ft.; superheater surface 343 sq. ft.; grate area 241 sq. ft.

The working pressure in these superheater engines was reduced to 160 lb. per sq. in. The total weight of the engine in working order was increased by these various modifications to 58 tons 5 cwt., distributed, as follows: On leading wheels, 14 tons 6 cwt., on driving wheels 15 tons 9 cwt., on intermediate wheels 14 tons 6 cwt., and on trailing wheels 14 tons 6 cwt. The tender was of the new type, as adopted on the No. 1 class, weighing 43 tons 2 cwt.