Midland Great Western/Great Southern 4-4-0 Locomotives in Ireland

Class As/A1 (Locobase 20494)

Data from "Superheater Passenger Engine; Midland Great Western Ry of Ireland", Locomotive Magazine, Volume XXII [22], Whole number 292 (15 December 1916). See also Steamindex entry "Class A" under the Midland Great Western Railway page, available at [], last accessed 18 January 2019.

Based on the 1905 MGW Celtic class described in Locobase 2686, the Mercuric was the first of the class to be reconfigured to include a superheater in the boiler. The Belpaire firebox remained unchanged as were the outer dimensions of the boiler, but 123 small tubes were replaced by the 18 flues that carried the superheater. Eight-inch (203 mm) piston valves replaced the slide valves.

Four were rebuilt with new frames and raised running boards in the 1920s; these were designated A1. 550 was deliberately derailed during the Irish Civil War. 549

Class Cs/540/D7 (Locobase 20651)

Data from "Superheater Passenger Engine; Midland Great Western Ry of Ireland", Locomotive Magazine, Volume XXIV [24], No 306 (15 April 1918). See also "MGWR Classes C and Cs" in Wikipedia at [], (citing Irish Railways In Pictures No. 2 The Midland Great Western Line. Irish Railway Record Society,London Area. November 1990), last accessed 10 October 2019.

Road numbers 4-5, 9, 12 had slide valves, 6-8, 10-11 had piston valves..Their names, in order of initial road number, were Ballynahinch, Croagh Patrick, Kylemore, Connemara, St. Patrick, Emerald Isle, Faugh a Ballagh, Erin go Bragh, and Shamrock.

Locomotive superintendent Edward Cusack's photo of the Kylemore (1911) shows a Belpaire firebox and a relatively short boiler and a driving wheelbase at the short end of those typical for locomotives with such tall drivers. Wikipedia comments that experience on express trains on the Sligo and Mayo branches was disappointing because the drivers slipped. Locobase notes that while the factor of adhesion seems more than adequate, the lead driving set's axle loading was five long tons (11,200 lb or 5,081 kg) higher than that on the trailing drivers. Could this have contributed to the slippage?

The class was soon reassigned to slow passenger trains on the Dublin-Galway run, but even there rough riding overtaxed bogie springs, which broke frequently.

The two classes differed in having slide valves (Great Southern 536 class/D7) or 8" (203 mm) piston valves (GSR 540/D6). Wikipedia says that the class was superheated in the 1920s, but at least the piston valve engines were delivered with superheaters (or fitted with them by the end of 1918). Later three of the D-valve engines replaced their Robinson installation with X-type superheaters.

Despite these limitations, the class remained in service into the late 1950s.