BNCR Class S
The Belfast and Northern Counties Railway (BNCR) Class S is a class of 2-4-2T steam locomotives that was introduced for service on the 3ft (914mm) narrow gauge lines of County Antrim in north east Ireland.
They were designed by Bowman Malcolm as a narrow gauge application of the Worsdell-von Borries system of two-cylinder compound locomotives that had been adopted by the BNCR. Limited space between the frames required them to have outside cylinders unlike their broad gauge counterparts. The smaller diameter high-pressure cylinder was on the left and the larger low-pressure one on the right.
Built for service on the Ballymena & Larne and Cushendall lines of the BNCR, members of the class were transferred to the Ballycastle Railway when that line was amalgamated with the Northern Counties Committee in 1924.
Some of the class were later rebuilt with a coal bunker at the rear to reduce the need to store coal inside the cab and had the wheelbase extended accordingly; these were reclassified as Class S1. One locomotive was heavily rebuilt as a 2-4-4T with a standard gauge boiler and reclassified Class S2.
| Class | Wheel arrangement |
Driving wheel diam |
Cylinders bore x stroke |
Boiler pressure |
Tractive effort |
Locomotive weight |
Remarks |
|---|---|---|---|---|---|---|---|
| S | 2-4-2T | 3ft 9ins | 14¾ & 21 x 20 | 160 | 13 150 | 31t 17cwt | |
| S1 | 2-4-2T | 3ft 9ins | 14¾ & 21 x 20 | 160 | 13 150 | 33t 0cwt | |
| S2 | 2-4-4T | 3ft 9ins | 14¾ & 21 x 20 | 200 | 16 438 | 42t 1cwt |