Great Western 0-4-2 Locomotives in Great_Britain


Class Details by Steve Llanso of Sweat House Media

Class 3521 (Locobase 20734)

Data from "Great Western Railway Broad Gauge Tank", Locomotive Magazine, Volume XXV [25] (15 May 1919), p. 77.

These saddle tanks immediately followed the dual-gauge side tanks shown in Locobase 3552. Like most late-era GWR broad-gauge engines, these were designed from the start to be convertible to the standard gauge that had been mandated decades before to be in place by 1892. On the 7' gauge, the drivers and trailing wheels were outside of both runs of the double frame. When converted to the 4' 8 1/2" gauge, the GWR relocated the wheels between the two frames and mounted cranks outside to take coupling rods.

Compared to the 3521 class, these engines had 12" (305 mm) shorter wheelbases between the rear driver and the trailer and a firebox shortened by 6" (152 mm).

As delivered, the class also proved to run unsteadily and were converted twice. All but 3543 and 3547 were rebuilt from April 1890 to May 1892 as 0-4-4Ts in a effort to damp out the oscillations, but the class suffered two more accidents. In 1899, the shops reworked the running gear to create a 4-4-0 tank engine.


Class 3521 (Locobase 3552)

An odd arrangement for a tank engine. This class had a long wheelbase between the trailing driving axle and the trailing carrying axle. As a result, the engines tended to sway and were modified as 0-4-4Ts. In this arrangement, two of them left the track in 1895. After a critical report on their suitability for fast running, the survivors were converted to 4-4-0 tender engines.


Class 48xx/14xx/58xx (Locobase 4537)

Data from Richard Drew's Great Central Railway site. See also an excellent description of ther origins and operation at the Gloucester-Warwickshire Railway website at [], last accessed 15 March 2009. See also John Daniel's [] where he says they were withdrawn beginning in 1956 and ending in 1964.

Although the 517-class autotrain locomotives were quite suitable to their service area, by the early 1930s, they were aging quickly. (Autotrains were light passenger trains consisting of one or two coaches semi-permanently coupled to a small steam locomotive.) So Swindon began producing a new design with a higher boiler pressure and ulitmately turned nearly 100. Like all Great Western locomotives, these had Belpaire fireboxes.

In the 1940s, the 75 4800-series engines were renumbered in the 1400 series. An additional 25 that were not delivered with auto-train controls were numbered in the 5800 series. Some of these would later received the ATC equipment.


Class 517 (Locobase 10401)

Data from "Four-Coupled Passenger Tank Locomotives, GWR", The Locomotive Magazine, Volume IX [9] (7 November 1903), p. 274. (It was around this time that LM first began using F M Whyte's classification system. In the opening paragraph, 517 is described as "a type having front coupled wheels and a trailing pair (0-4-2)...")

When George Armstrong first began producing this tank engine, its dimensions included a relatively small cylinder volume represented by 15" x 24" cylinders and it bore a saddle tank. Its weight came to 80,416 lb (35 tons 18 cwt). This group also had the short wheelbase of 13 ft 7 inches.

The design soon acquired side tanks and all were eventually fitted with Belpaire fireboxes and enlarged to the dimensions shown in the specifications. Frame design varied over the long production run resulting in three different wheelbase measurements. In addition to the short wheelbase on the first 60, all those between works 217 and works 463 had the 15 ft wheelbase shown in the specs. The last engines were stretched to 15 ft 6 inches.

After the first 60 locomotives were delivered in 1868-1870 (works number 71-130), GWR added to the stud beginning in 1873 and continuing to 1885:

Years Works numbers Engine numbers

1873-1875 217-240 826-849

1875-1876 277-288 1154-1165

1876 301-312 202-205, 215-222

1877 313-324 1421-1432

1877-1878 349-360 1433-1444

1883 434-445 1465-1476

1884-1885 458-469 1477-1488

After a 10-year break, Wolverhampton finished up the class with works 595-604, which took road numbers 3751-3580. Rebuilt and refurbished, members of this class remained in service for as long as 60 years. Several were refitted to operate auto-coach (auto-train) runs on light-traffic branch lines.


Class 517 rebuilt (Locobase 20950)

Data from "Rebuilt Tank Engine, Great Western Railway", The Locomotive Magazine, Volume XXIX [29] (15 January 1923), p. 4.

Beginning with the 517 in 1868 (Locobase 10401), George Armstrong's passenger tank appeared in several variants, each a bit bigger than the previous one. Rebuilt and refurbished, members of this class remained in service for as long as 60 years. Several were refitted to operate auto-coach (auto-train) runs on light-traffic branch lines.

In the mid-1920s, the GWR rebuilt the late-variant 1421 with a new boiler and firebox. Collett's use of a Belpaire firebox didn't enhance the 1421's appearance as its blunt square shape was noticeable between the side tanks.

Principal Dimensions by Steve Llanso of Sweat House Media

Class3521352148xx/14xx/58xx517517 rebuilt
Locobase ID20734 3552 4537 10401 20950
RailroadGreat WesternGreat WesternGreat WesternGreat WesternGreat Western
CountryGreat BritainGreat BritainGreat BritainGreat BritainGreat Britain
Whyte0-4-2ST0-4-2T0-4-2T0-4-2T0-4-2T
Number in Class19751661
Road Numbers3541-35403521-35404800517-576, 826-849, 1154-1165, 1421-1488,1421
Gauge7'StdStdStdStd
Number Built1975166
BuilderGWR - WolverhamptonGWR - WolverhamptonGWR - SwindonGWR - WolverhamptonGWR
Year18881887193218681922
Valve GearStephensonStephensonStephensonStephensonStephenson
Locomotive Length and Weight
Driver Wheelbase (ft / m)7 / 2.137 / 2.13 7.33 / 2.23 7.33 / 2.23 7.33 / 2.23
Engine Wheelbase (ft / m)16.50 / 5.0317.50 / 5.3315.50 / 4.7213.58 / 4.5715.50 / 4.72
Ratio of driving wheelbase to overall engine wheelbase 0.42 0.40 0.47 0.54 0.47
Overall Wheelbase (engine & tender) (ft / m)13.58
Axle Loading (Maximum Weight per Axle) (lbs / kg)36,960 / 16,76531,136 / 14,123
Weight on Drivers (lbs / kg)65,148 / 29,55172,576 / 32,92061,376 / 27,84055,600 / 25,22059,584 / 27,027
Engine Weight (lbs / kg)102,144 / 46,332107,296 / 48,66992,512 / 41,96378,800 / 35,74387,136 / 39,524
Tender Loaded Weight (lbs / kg)
Total Engine and Tender Weight (lbs / kg)102,144 / 46,332107,296 / 48,66992,512 / 41,96378,800 / 35,74387,136 / 39,524
Tender Water Capacity (gals / ML)960 / 3.641080 / 4.091080 / 4.09
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT)3
Minimum weight of rail (calculated) (lb/yd / kg/m)54 / 2760 / 3051 / 25.5046 / 2350 / 25
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)61 / 154961 / 154962 / 157562 / 157562 / 1575
Boiler Pressure (psi / kPa)160 / 11160 / 11165 / 11.40150 / 10.30165 / 11.40
High Pressure Cylinders (dia x stroke) (in / mm)17" x 24" / 432x61017" x 24" / 432x61016" x 24" / 406x61015" x 24" / 381x61016.5" x 24" / 419x610
Tractive Effort (lbs / kg)15,464 / 7014.3615,464 / 7014.3613,898 / 6304.0311,105 / 5037.1514,781 / 6704.56
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.21 4.69 4.42 5.01 4.03
Heating Ability
Tubes (number - dia) (in / mm)239 - 1.625" / 41193 - 1.625" / 41212 - 1.625" / 41186 - 1.75" / 44
Flues (number - dia) (in / mm)2 - 5.125" / 130
Flue/Tube length (ft / m)10.50 / 3.2010 / 3.0510.35 / 3.15
Firebox Area (sq ft / m2)109.50 / 10.17125 / 11.6283.20 / 7.7383.14 / 7.7295.81 / 8.90
Grate Area (sq ft / m2)18.90 / 1.7618.90 / 1.7612.80 / 1.1915 / 1.3914.70 / 1.37
Evaporative Heating Surface (sq ft / m2)1179 / 109.531195 / 111.06953 / 88.57988 / 91.79978 / 90.86
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)1179 / 109.531195 / 111.06953 / 88.57988 / 91.79978 / 90.86
Evaporative Heating Surface/Cylinder Volume186.99189.53170.63201.27164.66
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation30243024211222502426
Same as above plus superheater percentage30243024211222502426
Same as above but substitute firebox area for grate area17,52020,00013,72812,47115,809
Power L144544696417944324183
Power MT301.45285.30300.22351.47309.54

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