N1 Suburban Passenger Tank

The 0-8-2 tank engines of the 116 class, which were originally intended to deal with the heavy suburban passenger and goods traffic into and out of the Metrapolitan Railway’s underground lines, were even in their reduced dimensions still too much for the permanent way and works of that system, Mr. Ivatt transferred them elsewhere, as has already been noted, and proceeded to substitute for them a powerful type of tank engine, which should, however, be lighter on the track. Accordingly, in 1906, he built a locomotive with six-coupled wheels and a trailing radial pair, which had the following leading dimensions:

• Cylinders, 8-in. by 26-in.;
• diameter of six-coupled wheels, 5-ft. 8-in., and of trailing wheels, 3-ft. 8-in.;
• wheel-base: leading to driving wheels 7-ft. 3-in., driving to trailing coupled wheels 9-ft., trailing coupled to trailing radial wheels 7-ft. o-in., total 23-ft. 3-in.;
• boiler: length of barrel 10-ft. 1-in., diameter (outside) 4-ft. 8-in.; height of centre above, rails, 8-ft. 0 3/8 in.; working pressure, 170 lb. per sq. in.; heating surface: firebox 120 sq. ft., tubes 1,130 sq. ft, total 1,250 sq. ft.; grate area, 19 sq. ft.;
• capacity of tanks 1,600 gallons, and of bunker 4 tons;
• weight of engine in working order, 64 tons 14 cwt., of which 51 tons 4 cwt. rested on the six-coupled wheels.

This engine, No. 190, was succeeded by ten others of the same general design, but slightly modified in one or two details, the chief object of the change being to effect a more equable distribution of weight over the four pairs of wheels in view of the fact that some of the “foreign” lines South of London, on which these engines would be expected to run, did not allow the same maximum load per wheel as the G.N.R.. itself. Accordingly, the side tanks were shortened, and the end tank enlarged, and the wheel-base slightly lengthened behind the coupled wheels. These modified engines, one of which is shown in Fig. 113, had the following dimensions:

• Wheel-base: leading to driving wheels 7-ft. 3-in., driving to trailing coupled 9-ft., trailing coupled to trailing radial 7-ft. 6-in., total 23-ft. 9-in.;
• boiler: length of barrel, 10-ft, 1-in.;
• capacity of tanks 4,600 gallons, and of bunker 4 tons;
• weight of engine in working order, 65 tons 17 cwt., distributed as follows: on leading wheels, 16 tons 2 cwt.; on driving wheels, 18 tons; on trailing coupled wheels, 17 tons 5 cwt.; and on railing radial wheels, 14 tons 10 cwt.

All the engines of this class were, of course, fitted with condensing gear.

Below are given the dates, works numbers and running numbers of the series, including ten built this year: