Great Western 2-6-2 Locomotives in Great_Britain


Class Details by Steve Llanso of Sweat House Media

Class 31/41/51/61/81xx (Locobase 3586)

Good dual-service tanks built in several series and known as Large Prairies. (Inaccurately, since these tank locomotives adopted the 2-6-2 arrangement for very different reasons from those informing the design of the tender-engined type.)

Data is for the 5100s, which introduced the Standard #2 boiler (with Belpaire firebox) reflected in the data in place of the Standard #4. (These were originally delivered with 1,582 sq ft of heating surface area; tube heating surface was supplied by 289 tubes measuring 1 5/8" in diameter and 11 ft 4 5/16" in length.)

Boiler pressure went up to 225 psi in the 6100s (27,340 lb tractive effort).

8100-series engines came from the 5100 series using a Standard #2 boiler pressed to 225 psi and turning 66" wheels. (Weights were 118,272 lb on the drivers, 147,056 engine empty, 171,472 operating)

Reitrements spread out over decades with the last 11 closing out steam operations on the GWR in December 1965.

See [] (Information by John Daniel, 26 Sept 2004) for details on this class, including all names.

Here's his construction list:

Built: 1903 (3100)

1905/6 (3111 - 3149)

1906-8 (3150 - 3190)

1929 (5101 - 5110)

1930/1 (5150 - 5189)

1931-3 (6100 - 6159)

1934 (5190 - 5199)

1935 (6160 - 6169)

1935-9 (4100 - 4139)

1938/9 (3100 - 3104, 8100 - 8109)

1946-9 (4140 - 4179)


Class 44xx (Locobase 10478)

See [] (Information by John Daniel, 2000) for all names. [], accessed 2 September 2005. Also see "Locomotive Devleopments on the Great Western Railway," The Locomotive Magazine, Vol X (15 December 1904), pp. 208-209.

GJ Churchward variation on this wheel arrangement that was smaller than the 2-6-2T that came out 2 years before and had inside cylinders. Consequently, these known as "Small Prairies", a mis-application of the term for 2-6-2s. They operated on branch lines in the West Country and Wales. They had all-wheel compensation through springing and the radial axles in front and rear could have their fulcrums shifted as needed.

Locobase 2317 details the much larger class of 4500s that resulted when a larger driving wheel diameter was adopted. 4400s later received 17" cylinders and were superheated.

Retirements of the 4400s occurred in 1949-1955.


Class 45xx (Locobase 2317)

See [] (Information by John Daniel, 2000) for details on this class, including all names. [], accessed 2 September 2005. Also see "Locomotive Developments on the Great Western Railway," The Locomotive Magazine, Volume X [10] (15 December 1904), pp. 208-209.

GJ Churchward's "Small Prairies" began with a low-drivered batch produced in 1904 (see Locobase 10478). Their handy size and power were an immediate hit, but the design was thought to be lacking in potential speed.

So Swindon began delivering very similar engines with somewhat taller drivers, the change leading to the 4500 class identification. 55 were built in five batches in the 10 years of 1906-1915 and an additional 20 in 1924. Beginning with 4575, Charles Collett modified the design to accept sloping tanks of increased capacity. 100 were produced at Swindon from 1927-1929.

The [] account (accessed 18 August 2007) observes: "The class worked extensively in Wales and the West of England. One of the star turns of the class was hauling part of the Cambrian Coast Express to Pwllheli in the 1950s and 1960s, as well as parts of the Cornish Riviera Express. Despite their apparently small size, they were capable of good acceleration, and could haul passenger trains of up to 11 coaches." Llangollen also notes the drive-away price in 1928 of their example: 3,602 GBS ($18,010 in then-year USD).

The 4500s began leaving in 1950, the last going out in 1964.

See [] (Information by John Daniel, 2000) for details on this class, including all names. [], accessed 2 September 2005.

Principal Dimensions by Steve Llanso of Sweat House Media

Class31/41/51/61/81xx44xx45xx
Locobase ID3586 10478 2317
RailroadGreat WesternGreat WesternGreat Western
CountryGreat BritainGreat BritainGreat Britain
Whyte2-6-2T2-6-2T2-6-2T
Number in Class29011175
Road Numbers31, 41, 51 ,61, 8100+3100-3111 / 4400-44114500-4599, 55+
GaugeStdStdStd
Number Built29011175
BuilderGWR - SwindonGWR - Swindon
Year190319041906
Valve GearWalschaertStephensonStephenson
Locomotive Length and Weight
Driver Wheelbase (ft / m)14.75 / 4.5011.50 / 3.5111.60 / 3.54
Engine Wheelbase (ft / m)31.75 / 9.6826.50 / 8.0828 / 8.53
Ratio of driving wheelbase to overall engine wheelbase 0.46 0.43 0.41
Overall Wheelbase (engine & tender) (ft / m)31.75 / 9.6826.50 / 8.08
Axle Loading (Maximum Weight per Axle) (lbs / kg)39,424 / 17,882
Weight on Drivers (lbs / kg)121,072 / 54,917107,408 / 48,720
Engine Weight (lbs / kg)169,120 / 76,712126,896 / 57,559139,328 / 63,198
Tender Loaded Weight (lbs / kg)
Total Engine and Tender Weight (lbs / kg)169,120 / 76,712126,896 / 57,559139,328 / 63,198
Tender Water Capacity (gals / ML)2400 / 9.091200 / 4.551560 / 5.91
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) 4.50 / 4 1.70 / 24 / 4
Minimum weight of rail (calculated) (lb/yd / kg/m)67 / 33.5060 / 30
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)68 / 172749.50 / 125755.50 / 1410
Boiler Pressure (psi / kPa)200 / 13.80165 / 11.40200 / 13.80
High Pressure Cylinders (dia x stroke) (in / mm)18" x 30" / 457x76216.5" x 24" / 419x61017" x 24" / 432x610
Tractive Effort (lbs / kg)24,300 / 11022.3118,513 / 8397.3721,245 / 9636.58
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.98 5.06
Heating Ability
Tubes (number - dia) (in / mm)218 - 1.625" / 41255 - 1.625" / 41196 - 1.625" / 41
Flues (number - dia) (in / mm)6 - 5.125" / 1306 - 5.125" / 130
Flue/Tube length (ft / m)11 / 3.3510.50 / 3.20
Firebox Area (sq ft / m2)121.80 / 11.3295.70 / 8.8994.25 / 8.76
Grate Area (sq ft / m2)20.35 / 1.8916.83 / 1.5616.60 / 1.54
Evaporative Heating Surface (sq ft / m2)1267 / 117.751273 / 118.311087 / 101.02
Superheating Surface (sq ft / m2)82 / 7.6277 / 7.16
Combined Heating Surface (sq ft / m2)1349 / 125.371273 / 118.311164 / 108.18
Evaporative Heating Surface/Cylinder Volume143.40214.33172.40
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation407027773320
Same as above plus superheater percentage431427773552
Same as above but substitute firebox area for grate area25,82215,79120,170
Power L1670640146606
Power MT366.33406.78

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