| Introduced | 1866-1903 |
| Designer | Alexander McDonnell |
| Company | Great Southern & Western Railway |
| Weight | Engine – 37t 13cwt Tender – t cwt |
| Driving Wheels | 5ft 1¾ins |
| Boiler Pressure | 160psi |
| Cylinders | Inside – 18in x 24in |
| Tractive Effort | 17,170lbf |
The Great Southern & Western Railway (GS&WR) class 101of locomotives was easily the most numerous of any class of steam or diesel locomotive ever to run in Ireland. 111 were built between 1866 and 1903 with only minor modifications between batches. The great majority (91) were made by the GS&WR at Inchicore. The rest were contracted out to Beyer Peacock (12 works numbers 747-750, 780-783, 1251-1251-1252 & 2029-2030) and Sharp Stewart (8 works numbers 2155-2158, 2310-2311 & 2837-2838) who were both based in Manchester.
Interestingly GS&WR locomotives may have been the basis of the J15 class introduced by TW Worsdell on the Great Eastern Railway in England in 1883.
 | Great Eastern Railway class J15 introduced in 1883 |
There were still 96 of the locomotives in service by 1948 by which time they were owned by Córas Iompair Éireann (CIÉ) following the Transport Act of 1944. To put this in context the J15 class acoounted for nearly 22% of the steam locomotives on the CIÉ network.
Nearly half of the class were still in traffic when CIÉ terminated steam haulage on its network at the end of 1962. The locomotives whilst in service had been employed all over the 5 feet 3 inch gauge system in the Republic of Ireland on all duties from shunting to
Pilgrimage trains to stand-ins on occasional express passenger services. They were capable of achieving a speed of 60 mph
Preservation
Two members of the class have been preserved.
Preserved British Steam Locomotives 