Great Southern & Western 4-6-0 Locomotives in Ireland

Class Details by Steve Llanso of Sweat House Media

Class 362/B3 (Locobase 2762)

Data from "Ten-wheeled Goods Locomotive, Great Southern & Western Railway," The Locomotive Magazine, Vol XII (15 February 1906), p. 20. See also "Great Southern & Western Railway/Great Southern Railways" entry in at [], last accessed 7 February 2016; and E E Joynt, "The Modern Locomotives of the Great Southern and Western Railway", Locomotive Magazine, Volume XXIV [24] (15 July 1918), p. 46.

Burly freight engines that were the first Ten-wheelers in Ireland. They most resembled an 0-6-0 that received a longer boiler and a short-coupled bogie. Certainly the dimensions do not depict an especially large locomotive. Joynt described "very unusual, perhaps unique" valve motion details in this inside-cylinder locomotive. Inclining the cylinders at a 1 in 8 slope to clear the lead axle meant the slide bars weren't attached to the cylinder casting, but were "supported at the front end by a steel casting." The casting also bore "the rocking shaft brackets, and at the back end by a second cast steel motion plate."

According to steamindex's summary: "They were unpopular due to their rough riding and proneness to derailment due to the lightness of the front end." Indeed, the conversion of the 355 class 0-6-0s to 2-6-0 Moguls met the requirements equally well and Coey produced no more 4-6-0 goods locomotives.

The class was retired between 1928 and 1931.

Class B2 (Locobase 2336)

Data from "New 4-6-0 Type Express Passenger Engine, Great Southern & Western Railway", Locomotive Magazine, Volume 23 (15 February 1917), p. 29-31; Ahrons (1927); and "Great Southern & Western Railway/Great Southern Railways" entry in at [] . The GSW's Inchicore Works produced the 401 in 1916 and 401-402 and 406 in 1921. Armstrong-Whitworth built the 404-405 and 407-409 in 1923.

These engines, designed by EA Watson, were not completely successful in their four-cylinder incarnation. They were laid out with the outside cylinders in line with the rear bogie wheels; these drove the middle coupled axle. The inside pair drove the leading coupled axle. Two 8" (203 mm) piston valves were placed so that the one on each side served both cylinders on that side. The Belpaire firebox was mated to a quite sizable boiler.

Steamindex quotes Clement and McMahon's negative evaluation of the Watson design. It "suffered from short travel valves and Schmidt wide-type single piston rings (the cause of trouble on the LMS Royal Scot class). The steam pipes were badly designed, and an attempt to improve the layout with external pipes on No. 407 must have led to considerable heat loss (page 238: illustrated page 237)."

Clement and McMahon, steamindex adds, also suggest "that the Armstrong Whitworth locomotives may have been badly built: 'on 3 June 1927, the Board had authorised investigation of legal action in respect of the failure of driving wheel tyres on all the Armstrong Whitworth built engines.'".

Beginning in 1927, seven were rebuilt as two-cylinder locomotives with 19" x 28" cylinders (tractive effort 20,620 lb). 401 and 406 also received the Caprotti valve gear and were known to be fast and economical engines.

Class Maeve (Locobase 2337)

Data from, last accessed 6 April 2012 and "More Light on the 800 Class", RPSI's Five-Foot-Three Journal, Issue 52 , pp. 28-32.

Very successful home-built design with tapered boiler barrels and Belpaire fireboxes. Three relatively large cylinders offered the same volume as many four-cylinder simple Ten-wheeler. They used steam introduced by long-travel (6 3/4"/171 mm), 9"(279)-diameter piston valves from the relatively small boiler, which had one of the smallest evaporative heating surface area to cylinder volume ratios of all British and Irish 4-6-0s. But firebox heating surface area rivalling any British 4-6-0 coupled with generous superheater area suggests a determination to wring every last BTU out of the steam. A double chimney, the front one for the two outside cylinders, the rear one for the center-mounted can, exhausted the steam.

Their weight and outer dimensions represented one of the few instances in which the greater span of the 5' 3" gauge was fully exploited. Modern features included roller bearings on the leading bogie axles and the four tender axles. The radial constant-lead motion used ball bearings and needle roller bearings served the quadrant link trunnion and the eccentric rod ends.

Names were Maeve, Macha, and Tailte and the three sisters hauled the Dublin-Cork express over the 266-km (165-mile) route. Through October 1940, notes the RPSI commentary by W T Scott, the class easily met Chief Mechanical Engineer Edgar Bredin's design goal of travelling 200,000 miles (322,000 km) before its main overhauls. Impressive in its own right and more so when Bredin compared that accomplishment with the 60,000 miles (96,600 km) for LMS 4-6-0s and 80,000 (128,800 km)

for those of the LNER's 4-6-0s.

Their power and speed was only sporadically called upon given wartime impacts on coal quality. The class later ran with boilers set to pop at 180 psi (12.4 bar) , which undoubtedly reduced maintenance demands from these high-strung machines. By the 1950s, the adoption of diesel power had relegated them to secondary service.

Tailte was taken out of service in 1955 and Maca withdrawn in 1957; both were scrapped. Only Maeve, retired last in 1962, was preserved by the Ulster Folk and Transport Museum. According to the Museum's website ([]-, last accessed 9 April 2017), the Maedb (as her name is rendered in Gaelic) traveled 480,000 miles (772,800 km) and reached a top speed of 96 mph (155 kph).

Principal Dimensions by Steve Llanso of Sweat House Media

Locobase ID2762 2336 2337
RailroadGreat Southern & WesternGreat Southern & WesternGreat Southern & Western
Number in Class6103
Road Numbers362-367400-409800-802
Number Built6103
BuilderInchicore WorksseveralInchicore Works
Valve GearStephensonWalschaertWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)14.50 / 4.4215.25 / 4.6515.75 / 4.80
Engine Wheelbase (ft / m)24.87 / 7.5827.08 / 8.2628.92 / 8.81
Ratio of driving wheelbase to overall engine wheelbase 0.58 0.56 0.54
Overall Wheelbase (engine & tender) (ft / m)49.3367.50 / 20.57
Axle Loading (Maximum Weight per Axle) (lbs / kg)34,832 / 15,80038,752 / 17,57847,000 / 21,319
Weight on Drivers (lbs / kg)98,784 / 44,808113,568 / 51,514141,000 / 63,957
Engine Weight (lbs / kg)127,680 / 57,915158,368 / 71,835188,160 / 85,348
Tender Loaded Weight (lbs / kg)78,400 / 35,56281,312 / 36,883114,240 / 51,818
Total Engine and Tender Weight (lbs / kg)206,080 / 93,477239,680 / 108,718302,400 / 137,166
Tender Water Capacity (gals / ML)4014 / 15.206000 / 22.73
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) 7.70 / 7 8.90 / 8.10
Minimum weight of rail (calculated) (lb/yd / kg/m)55 / 27.5063 / 31.5078 / 39
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)61.75 / 156879 / 200779 / 2007
Boiler Pressure (psi / kPa)160 / 11175 / 12.10225 / 15.50
High Pressure Cylinders (dia x stroke) (in / mm)19.25" x 26" / 489x66014" x 26" / 356x660 (4)18.5" x 28" / 470x711 (3)
Tractive Effort (lbs / kg)21,220 / 9625.2419,191 / 8704.9034,799 / 15784.58
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.66 5.92 4.05
Heating Ability
Tubes (number - dia) (in / mm)227 - 1.75" / 44173 - 1.75" / 44143 - 2" / 51
Flues (number - dia) (in / mm)24 - 5" / 12728 - 5.5" / 140
Flue/Tube length (ft / m)14.10 / 4.3014.58 / 4.4414.48 / 4.41
Firebox Area (sq ft / m2)133 / 12.36158 / 14.68200 / 18.58
Grate Area (sq ft / m2)24.80 / 2.3028 / 2.6033.50 / 3.11
Evaporative Heating Surface (sq ft / m2)1600 / 148.651772 / 164.621870 / 173.73
Superheating Surface (sq ft / m2)440 / 40.88468 / 43.48
Combined Heating Surface (sq ft / m2)1600 / 148.652212 / 205.502338 / 217.21
Evaporative Heating Surface/Cylinder Volume182.69191.26143.11
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation396849007538
Same as above plus superheater percentage396858809045
Same as above but substitute firebox area for grate area21,28033,18054,000
Power L1425916,22016,056
Power MT285.15944.60753.14

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