Great Western 2-2-2 Locomotives in Great_Britain


Class Details by Steve Llanso of Sweat House Media

Class 10 (Locobase 3548)

Data from E L Ahrons, The British Railway Locomotive, 1825-1925 (London: Locomotive Publishing Company, 1926), p. 264.

Like Number 9, this engine was the only one in its class. It ran somewhat faster than the 9, says Ahrons, but still was converted to a seven-footer in 1890. Another Ahrons reference led to a Locobase entry citing 1865. That variant has been deleted, but on less than solid evidence.


Class 157 (Locobase 2209)

Data from Ahrons (1927). See also "The 'Sharpie' Singles, Great Western Railway," The Locomotive Magazine, Vol XIII (15 January 1907), pp. 11-14. See also E L Ahrons' update of the "157-166 Class", Locomotive Magazine, Volume XIX [19] (15 February 1913), p. 38.

Designed by Daniel Gooch for the standard gauge and considerably smaller than his wide-gauge brutes. Engine used a double-sandwich frame and inside frames. They were later replaced by an 1872 class of locomotives with the same numbers, but a larger boiler; see Locobase 10602. The LM report notes that after 17 years' service, they were regarded as too light for the trains then being hauled and also not worth rebuilding.

NB: The tube and flue length is estimated based on a calculation of the given tube diameter and count.


Class 157 (Locobase 3535)

Data from E L Ahrons, The British Railway Locomotive, 1825-1925 (London: Locomotive Publishing Company, 1927); and "GWR 157 Class (Dean)" in Wikipedia at []), last accessed 6 November 2023.

William Dean design described by Ahrons as the "probably the most graceful express engines of their day." These engines used a sandwich frame with oak planking, which made for a more supple ride. Wikipedia stated that the 157s were not rebuilds as once thought, but a new class on the Joseph Armstrong engines that preceded them They had two nicknames ("Sharpies" because of their supposed Sharp, Stewart origins) and "Cobhams"after 162's name.

As with most Great Western singles, the 157s took their turn hauling express trains for decades before giving way to larger locomotives. The class was retired in 1903-1906.


Class 157 - 1872 (Locobase 10602)

Data from "The 'Sharpie' Singles, Great Western Railway," The Locomotive Magazine, Vol XIII (15 January 1907), pp. 11-14. Boiler pressure is an estimate.

William Dean built this class to replace the 1862 "Sharpies" described in Locobase 2209. Compared to the earlier locomotives, the boiler was smaller, but the grate larger. Although not produced by Sharp, Stewart, their similarity to the earlier engines and the adoption of the same set of numbers led to their being nicknamed "Sharpies", too.

They have been described as "...probably the most handsome type of Great Western engines built for the standard gauge, being neater as regard detail than the engines they succeeeded." They later received new boilers that had 1,328 sq ft of total heating surface, 119.4 sq ft of which was direct, and the grate grew further to 21 sq ft.


Class 69 (Locobase 3498)

Data from E L Ahrons, "Great Western Railway, Engines 69-76", Locomotive Magazine, Volume XIX [19] (15 January 1913), pp. 17-19.

Designed by Daniel Gooch for the standard gauge, this class owned two distinctions: They were the first built for standard-gauge running on the Great Western, and they were the first locomotives produced by Beyer, Peacock & Co. Works numbers were 1-4 in September 1855 and 15-18 in March-May 1856.

The three axles were compensated by levers visible between the axles under the frame. The ends of these levers rested on india-rubber pads. The leading axle had long, "open-plated" springs that, according to Ahrons (1927), afforded "very easy and smooth riding." The locomotives were later rebuilt (Locobase 15901), at which point the compensating levers were removed.

Boiler pressure is an estimate and is probably low. As with many Gooch engines, the boiler is more than generous in relation to the grate. Clearly, the designers relied on the high calorie-count of the Welsh coal usually burned on such small grates.


Class 69 - 1872 rebuild (Locobase 15901)

Data from E L Ahrons, "Great Western Ry Engines Nos. 69 to 76", The Locomotive [Magazine], Volume 19, No. 245 (15 January 1913), pp. 19-21, and Volume 19 (15 February 1913), pp. 37-38.

Ahrons describes these updated locomotives first delivered in 1855 and described in Locobase 3498 as "completely rebuilt" at the GWR's Wolverhampton Works. He adds "[I]t may as well be stated that very little, if anything, of the original engines remained after this rebuilding."

In that spirit, Locobase considers these new engines. Everything from the larger boiler, greater number of smaller-diameter tubes, longer wheelbase, taller drivers, larger grate (but less firebox area), greater weight was different.

Ahrons commented that they were up to the greater demands of the 1870s as well. Their new boilers had "very generous proportions", a quality he felt accounted for their great success. They were always "great favourites" that could "generally outrun the 7-ft singles as regards speed, though they could not take quite such a heavy train as the 'Sir Alexander' class."

Ahrons further reported in the February issue that the class received new boilers in 1885-1891. 69, 73, 75-76 had tube counts in their three-ring boilers drop by four to 248 and heating surface area fell to 1,287 sq ft (119.57 sq m). 70-72 and 73 had two-ring boilers with larger domes, still fewer tubes (239), slightly larger fireboxes offering 104 sq ft (9.66 sq m) of heating surface area for a total evaporative heating surface area of 1,250 sq ft (116.13 sq m), but reduced grate area of 15.25 sq ft (1.42 sq m).

Still later, said Ahrons, the Great Western applied the "sailor's knife" [aka the "irishman's axe"] principle (three new blades, two new handles ...) and were rebuilt as 2-4-0s of the River class in 1895. Their two-course boilers now had the domes on the rear ring, iron in place of the original brass axleboxes, and I-section coupling rods. And, added Ahrons, the class now basked in the "glory of names of rivers", being dubbed Avon, Dart, Dee, Exe, Isi, Stour, Teign, and Wye.

Old-new locomotives for sure, but 74-76 were fitted in the early teens with Belpaire fireboxes.


Class 9 (Locobase 3547)

Data from E L Ahrons, The British Railway Locomotive, 1825-1925 (London: Locomotive Publishing Company, 1926), p. 264.

A one-engine class built by William Dean, this single had inside cylinders and valves actuated by an outside Stephenson's link motion. The arms of the eccentric arms were only just visible behind the frame. Ahrons noted that it could pull very heavy trains (although starting must have been a delicate task with such a low F/A), but that it was inferior to the seven-foot singles already in service. Number 9 was converted to an outside-bearing seven-footer a few years hence.


Class Ajax (Locobase 3032)

Although OS Nock (RWC I, pl 88) and Gustav Reder (Michael Reynolds, trans), The world of steam locomotives (New York: Putnam, 1974) have different illustrations of this class, they agree that the design was a failure (and that the drivers were plated over). In the Reder reprint of an earlier chart of GW locomotive classes, the boiler is nearly domeless, the firebox gothic, the bolted frame deeply curved over the tall driver, and the carrying wheels spoked. In the Nock illustration, the tall driver is carried by a straight frame with odd over and under axle horns, the axle riding in the upper and the spring carried in the lower. The steam dome is perched on top of a low firebox, another dome sits forward just behind a much shorter stack, and all wheels are plated.

"It is on record, "says Nock in summary, "that neither Ajax or the sister engine, Mars, did any useful work on the line."


Class Apollo (Locobase 10177)

Data from "The BG Locomotives of the Great Western Ry", The Locomotive Magazine, Vol VI (February 1901), p. 43.

Charles Tayleur works numbers were 62-64. Boiler pressure is an estimate.

This trio continued the line of early singles and are sometimes described as sisters to the Vulcans (Locobase 658). Apollo, Neptune, and Venus were smaller and hence less powerful. Neptune was said to be singularly unsteady. All of them were eventually converted to tank engines and the LM's author again asserts "...it may be truly be said that none of these six engines ever accomplished any good purpose."


Class Evening Star (Locobase 10185)

Data from "The BG Locomotives of the Great Western Ry", The Locomotive Magazine, Vol VI (May 1901), p. 83. Boiler pressure is an estimate as is the grate area.

Also originally destined for the New Orleans Railroad (as were the North Star and Morning Star - Locobase 657), these were similar to the earlier Stars, but had a more typical bore-to-strike ratio. The boiler had its two safety valve columns arranged one behind the other ahead of the hemispherical firebox dome and the tall stack.

The Dog Star may have had the same dimensions, but another source gave a tube count of 114 (of greater length) and a bigger firebox. The result was a total heating surface of 754 sq ft, of which the direct heating surface accounted for 88.68 sq ft.


Class Fire Fly (Locobase 659)

Data from

G. Drysdale Dempsey A Rudimentary Treatise on the Locomotive Engine (1857; reprint 1970) .

This was the lead engine of a very large class that included 2-4-0 and 0-6-0 wheel arrangements all built to a common design. All engines had a composite sandwich frame of thin iron plates around oak, gothic boiler domes over coke-burning fireboxes, and gab gear later replaced by Stephenson link. These engines were well known for fast and steady running. The last of them --Ixion -- was retired in 1879.

Those built by different engine constructors included:

Jones, Turner, and Evans (Newton-le-Willows)

FIRE FLY, SPIT FIRE, WILD FIRE, FIRE BALL, FIRE KING, FIRE BRAND.

Sharp, Roberts, and Co (Manchester)

TIGER, LEOPARD, PANTHER, LYNX, STAG, VULTURE, HAWK, FALCON, OSTRICH, GREYHOUND.

Fenton, Murray, and Jackson (Leeds)

CHARON, CYCLOPS, CERBERUS, PLUTO, HARPY, MINOS, IXION, GORGON, HECATE, VESTA, ACHERON, EREBUS, MEDEA, HYDRA, LETHE, PHLEGETHON, MEDUSA, PROSERPINE, GANYMEDE, ARGUS

G & J Rennie (Blackfriars)

MAZEPPA, ARAB

RB Longridge & Co (Bedlington)

JUPITER, SATURN, MARS, LUCIFER, VENUS, MERCURY

Stothert & Slaughter (Bristol)

ARROW, DART

Nasmyth, Gaskell, & Co (Manchester)

ACHILLES, MILO, HECTOR, CASTOR, MENTOR, BELLONA, ACTAEON, CENTAUR, ORION, DAMON, ELECTRA, PRIAM, POLLUX, PHOENIX, PEGASUS, STENTOR.

Stentor was the last delivered in December 1842.

Ixion carried the banner for the Broad Gauge in the 1846 trials that pitted her against the specially built A from Robert Stephenson. She won, hands down, pulling a 61-ton train at 52.4 mph (84.4 kph) between London and Didcot and reaching 47.8 mph (80.0 kph) with an 81.5 ton trailing load. Although legislation imposed standard gauge on the railway network (the last broad gauge run coming in 1892), broad gauge engines continued to outperform standard-gauge engines for many years.


Class Gazelle (Locobase 10193)

Data from "The BG Locomotives of the Great Western Ry", The Locomotive Magazine, Vol VI (July 1901), p. 117.

These two batches of tanks were produced by builders other than the GWR. They were essentially similar to the Sun tank conversions, but with slightly bigger boilers.

Five came from Sharp, Roberts, had works numbers of 117, 119, 122, 129, and 135 and names were Gazelle, Giraffe, Antelope, Wolf, and Zebra. Slaughter & Company added 8 more named for stabbing weapons of various kinds: Javelin, Djerid, Yataghan, Lance, Assegai, Rocket, Stiletto, and Creese (more often known as Kris).


Class Great Britain (Locobase 9062)

Data from A H Malan, "New Narrow-Gauge Great Western Engines", English Illustrated Magazine (1893), pp. 199-203.

Locobase 3028 gives the details of the Dean Single class of 80 singles. Some of these were delivered as broad-gauge engines and Malan supplied the details of the Great Britain as a contrast with the new narrow-gauge engines then coming on the line.


Class Great Western (Locobase 2571)

Data from "The BG Locomotives of the Great Western Ry", The Locomotive Magazine, Vol VI (August 1901), p. 135. See also "The Leviathan Locomotive 'Great Western'", Railway Register and Record of Public Enterprise for Railways, Volume IV [4], (London: Railway Register, 1846), pp. 21-32.

Classic Daniel Gooch design that was in production in small numbers (a total of 54) for 40 years. Taking full advantage of the broad gauge to produce a big boiler and stable locomotive, Gooch at first produced this engine as a 2-2-2. Virtually the ultimate expression of 7-foot gauge express power, the Great Western averaged 67 mph over a 53-mile stretch in 1846, years before any standard-gauge design would break 60 mph.

The design, by chief mechanic Daniel Gooch, initially retained the domed firebox although later engines (Cf Lord of the Isles) had a domeless boiler. When the engine showed the strain of carrying so much weight on three axles by breaking one, the design was converted to a 4-2-2. Note that the guiding axles were not carried in a truck but rigidly mounted in individual axle horns.

The 1901 survey of GWR locomotives offers a comment on the difficulties of building a "Haystack" firebox in those days that deserves to be quoted: "The corner-plates had to be compressed in dies by the continued hammering of heavy hand mallets," (an arresting image of Haephaestus at his forge) "for it is unnecessary to say that there were then no flanging presses,hydraulic rivetters, tube rollers, pneumatic caulkers or the other modern substitutes for laborious hand work, though they certainly had bending rolls and shearing and punching machinery even at that early date."

Glover (1967) and Hollingsworth (1982) both note the advantages of broad gauge, which were fully exploited in this series of engines. Broad gauge meant wide fireboxes with larger heating surfaces, large boilers, and large valves. Given good coal, these engines steamed easily. The 4-2-2 layout could be a slippery one, but all in all, these were very good engines. When the GW was converted to standard gauge, they were regretfully retired.


Class Lion (Locobase 3031)

Data from "The BG Locomotives of the Great Western Ry", The Locomotive Magazine, Vol VI (March 1901), p. 61.

Smallish Patentee type with the curved frame over the driver characteristic of the Sharp, Roberts variation of the design. Unlike many of the other 3-axle singles being acquired by the GWR at the time, this trio -- Lion, Atlas, and Eagle -- had much more separation between the first axle and the driving set than between the driving set and the trailing axle. The author refers to the layout's "novel manner" but adds: "...a good distribution of the total weight was, however, secured.

Two other locomotives with straight frames and 76" drivers and slightly different heating surface areas were converted from a gear-driven pair of locomotives named Snake and Viper and originally supplied by Haigh Foundry Company (of Wigan). When they were converted to a more conventional layout, they were renamed Teign & Exe. (See Locomotive Magazine, Vol VI (November 1901), p. 187, footnote.

After 22 years of service in this arrangement, all three were converted to tank engines in 1960.


Class North Star (Locobase 657)

Data from E L Ahrons, The British Railway Locomotive, 1825-1925 (London: Locomotive Publishing Company, 1927)..

One of the first to run on IK Brunel's 7-foot gauge. North Star had works number 150. Her sister was called the Morning Star (works number 149); she had 78" drivers and two more tubes for slightly more total heating surface (716 sq ft). The two engines were ordered on for the American New Orleans Railroad, which was to be built to 5'6" gauge.

When North Star was delivered, its performance was very disappointing, being unable to pull more than 16 tons of train at 40 mph.

According to Lionel A.Smith [] (viewed 20 September 2004), Daniel Gooch and Brunel modified the design in several ways, including "increasing the size of the blast pipe and ensuring that the exhaust steam was discharged up the middle of the chimney" Now the North Star "..proved capable of pulling 40 tons at 40 mph and using less than a third of the quantity of coke at that." Other accounts indicate that the North Star could now haul 110 tons at 30 mph.

In service until 1870 and preserved until 1906 when it was scrapped for lack of space in the Science Museum. Rebuilt in 1854 with 16 x 18" cylinders and longer boiler tubes (now 9 ft 10 3/4"), which yielded a heating surface that included 756 sq ft of tubes and 94 sq ft of firebox heating surface.


Class North Star - modified (Locobase 10170)

Data from "The BG Locomotives of the Great Western Ry", The Locomotive Magazine, Vol VII (February 1901), p. 23. Boiler pressure is an estimate.

This single's early days are described in Locobase 657. The rebuilding of locomotives from so early a period of steam railroading was only to be expected. Of interest here is the increase in stroke from a full-square ratio, the provision of a domeless boiler of much more "modern" appearance, and the use of the same number of tubes of slightly greater (1/8") diameter.

In service until 1870 by which time North Star had run 429,000 miles and preserved until 1906 when it was scrapped for lack of space in the Science Museum.


Class Polar Star (Locobase 10186)

Data from "The BG Locomotives of the Great Western Ry", The Locomotive Magazine, Vol VI (May 1901), p. 83; and E L Ahrons, The British Railway Locomotive, 1825-1925 (London: Locomotive Publishing Company, 1927).

This "Star" had larger cylinders than the Evening and Dog Stars (Locobase 10185) and a larger grate.


Class Premier (Locobase 10178)

Data from "The BG Locomotives of the Great Western Ry", The Locomotive Magazine, Vol VI (February 1901), p. 44.

Works numbers were 40-41. Boiler pressure is an estimate.

According to the LM article's author, Premier and Ariel were examples of "...the theory of short stroke and reduced piston speed ...being carried to an extreme." So these were weak engines indeed. Locobase also enjoyed LM's observation about "the curious feature" of the spokes of the wheels. The extremely tall drivers had 28 spokes while the considerably smaller carrying wheels had 24, "...the crowded condition of the latter being particularly noticeable."


Class Sun (Locobase 10188)

Data from "The BG Locomotives of the Great Western Ry", The Locomotive Magazine, Vol VI (June 1901), p. 101.

This was essentially a reduced version of the 7-footers and was intended to address the steeper profiles offered by the western regions of the GWR . Eight were produced by R & W Hawthorn (works 291-294, 316-318). Comet, Aurora, and Hesperus had 15"-diameter cylinders. Others were built by Stother & Slaughter (8), and Sharp, Roberts (5).

The class proved disappointing in its original configuration, so the GWR converted them to tank engines; see Locobase 10192.


Class Sun - tank (Locobase 10192)

Data from "The BG Locomotives of the Great Western Ry", The Locomotive Magazine, Vol VI (June 1901), p. 101.

As noted in Locobase 10188, the Suns were not brilliant successes as tender-trailing express locomotives. Very soon after their introduction they were converted to tank engines as shown in the specifications. Note the increase in boiler pressure and the substantially larger firebox. In this form, the class lasted into the 1870s.


Class Vulcan (Locobase 658)

According to a chart of Early Locomotive Engines of the Great Western Railway reproduced in Reder (1974), the Vulcan was designed by a Mr. Tayton. (Possibly meaning the Charles Tayleur & Co, the original company that became Vulcan Foundry.) Also see "The BG Locomotives of the Great Western Ry", The Locomotive Magazine, Vol VI (February 1901), p. 24-25. Also see Francis Whishaw, The railways of Great Britain and Ireland practically described and illustrated. (London: John Weale, 1842).

Vulcan works numbers were 51-53 and the other two engines were Aeolus and Bacchus. Boiler pressure is an estimate.

The remarks on the chart also note that this first of the tall-drivered Great Western locomotives was later converted into a tank engine. The 1901 LM article cited an alternative set of dimensions offered by Francis Whishaw who credited the Vulcan with 147 tubes measuring 1 5/8" in diameter and 8 ft 6" long which somehow results in a larger firebox (57.15 sq ft) and a smaller tube heating surface area (529.78 sq ft vs the usually quoted 652.5 sq ft). The BG article author notes that all of the locomotives were "severely" rebuilt at a "very early date."

The Vulcan was, "...if truth must be told," says the LM author, "a consistent failure. Only one trip with this engine is recorded in which she took a load of 18[!] tons to West Drayton at an average speed of 28.32 miles per hour and returned with 14 1/2 tons at the rate of 21 miles per hour." After noting that none of this class ever would amount to much, the author adds that Sir Daniel Gooch "... spoke favourably of them in comparison with some of the other atrocities put upon this line in its first days."

As delivered, both Aeolus and Bacchus had fluted and lagged domes positioned over the firebox. Aeolus, like Vulcan, was later converted to a tank engine. Bacchus later served as a ballast engine supporting construction of the GWR line past Maidenhead. See Locobase 10177 for the other three Tayleur locomotives of the time - also failures.


Class unknown (Locobase 3511)

Data from E L Ahrons, The British Railway Locomotive, 1825-1925 (London: Locomotive Publishing Company, 1927).; and H. Michell Whitley, Assoc. M.I.C.E., F.G.S., Scientific American Supplement, No. 458 (11 October 1884), p. 7308, reproduced by Project Gutenberg at ftp://sailor.gutenberg.lib.md.us/gutenberg/1/1/6/4/11647/11647-8.txt, first accessed 25 January 2007, later link [], last accessed 16 October 2022.

Joseph Armstrong design that used the Gooch firebox layout of a "midfeather" dividing the grate into two sections and having a water pocket along the top. Ahrons took particular notice of the "exceptionally long" wheelbase that "resulted in a very steady engine at high speeds."

These were later rebuilt by Dean (1884-1887) when they received domed boilers and the midfeather was deleted.

See Ahrons (1927) for data, where he comments that this class worked the fastest standard-gauge expresses to the end of the century. Further information was published in the Scientific American Supplement, No. 458 contains Whitley's summary: "These engines are extremely simple, but well proportioned, and are a very handsome type, and their average consumption of coal, working trains averaging ten coaches, is about 24.87 lb. per mile [7.00 kg/km]."


Class unknown (Locobase 9137)

Data from Mr Edward Woods, Address to the Institution of Civil Engineers 9 November 1886 (London: ICE, 1886), p. 61.

The date is an estimate, but intended to reflect the long-standing production run that produced dozens of Great Western singles.

Principal Dimensions by Steve Llanso of Sweat House Media

Class10157157157 - 187269
Locobase ID3548 2209 3535 10602 3498
RailroadGreat WesternGreat WesternGreat WesternGreat WesternGreat Western
CountryGreat BritainGreat BritainGreat BritainGreat BritainGreat Britain
Whyte2-2-22-2-22-2-22-2-22-2-2
Number in Class11010108
Road Numbers10157-166157-166157-16669-76
GaugeStdStdStdStdStd
Number Built11010108
BuilderGWR - SwindonSharp, StewartGWR - SwindonGWR - SwindonBeyer, Peacock
Year18841862187818791855
Valve GearStephensonStephensonStephensonGooch
Locomotive Length and Weight
Driver Wheelbase (ft / m)
Engine Wheelbase (ft / m)18 / 5.4916 / 4.8817.66 / 5.3817.67 / 5.3915.50 / 4.72
Ratio of driving wheelbase to overall engine wheelbase
Overall Wheelbase (engine & tender) (ft / m)
Axle Loading (Maximum Weight per Axle) (lbs / kg)36,960 / 16,76536,960 / 16,76536,960 / 16,765
Weight on Drivers (lbs / kg)36,960 / 16,76528,678 / 13,00836,960 / 16,76536,960 / 16,765
Engine Weight (lbs / kg)91,840 / 41,65866,572 / 30,19780,976 / 36,73080,976 / 36,730
Tender Loaded Weight (lbs / kg)
Total Engine and Tender Weight (lbs / kg)
Tender Water Capacity (gals / ML)
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT)
Minimum weight of rail (calculated) (lb/yd / kg/m)62 / 3148 / 2462 / 3162 / 31
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)92 / 233784 / 213484 / 213484 / 213478 / 1829
Boiler Pressure (psi / kPa)160 / 11130 / 9140 / 9.70140 / 9.70120 / 8.30
High Pressure Cylinders (dia x stroke) (in / mm)18" x 26" / 457x66016" x 24" / 406x61018" x 24" / 457x61018" x 24" / 457x61015.5" x 22" / 394x559
Tractive Effort (lbs / kg)12,453 / 5648.598082 / 3665.9411,016 / 4996.7811,016 / 4996.786912 / 3135.23
Factor of Adhesion (Weight on Drivers/Tractive Effort) 2.97 3.55 3.36 3.36
Heating Ability
Tubes (number - dia) (in / mm)248 - 1.625" / 41187 - 2" / 51228 - 1.625" / 41228 - 1.625" / 41193 - 2" / 51
Flues (number - dia) (in / mm)4 - 1.5" / 38
Flue/Tube length (ft / m)11 / 3.3511.33 / 3.4511 / 3.3511.33 / 3.45
Firebox Area (sq ft / m2)137.70 / 12.80122 / 11.33115 / 10.68115 / 10.69109.80 / 10.20
Grate Area (sq ft / m2)18.30 / 1.7014.60 / 1.3619.30 / 1.7919.30 / 1.7913.60 / 1.26
Evaporative Heating Surface (sq ft / m2)1292 / 120.071248 / 115.941215 / 112.881214 / 112.831112 / 103.31
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)1292 / 120.071248 / 115.941215 / 112.881214 / 112.831112 / 103.31
Evaporative Heating Surface/Cylinder Volume168.72223.45171.89171.75231.44
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation29281898270227021632
Same as above plus superheater percentage29281898270227021632
Same as above but substitute firebox area for grate area22,03215,86016,10016,10013,176
Power L163456055496349615393
Power MT378.47465.48296.04295.92

Principal Dimensions by Steve Llanso of Sweat House Media

Class69 - 1872 rebuild9AjaxApolloEvening Star
Locobase ID15901 3547 3032 10177 10185
RailroadGreat WesternGreat WesternGreat WesternGreat WesternGreat Western
CountryGreat BritainGreat BritainGreat BritainGreat BritainGreat Britain
Whyte2-2-22-2-22-2-22-2-22-2-2
Number in Class81232
Road Numbers69-769 0
GaugeStdStdStd7'7'
Number Built81232
BuilderGWRGWR - SwindonMather & DixonVulcan FoundryRobert Stephenson & Co
Year18721884183818381839
Valve GearGoochStephensonGabGab
Locomotive Length and Weight
Driver Wheelbase (ft / m)
Engine Wheelbase (ft / m)17 / 5.1818 / 5.4913 / 3.9613.25 / 4.0412.42 / 3.79
Ratio of driving wheelbase to overall engine wheelbase
Overall Wheelbase (engine & tender) (ft / m)21.75 / 6.63
Axle Loading (Maximum Weight per Axle) (lbs / kg)31,360 / 14,22533,600 / 15,241
Weight on Drivers (lbs / kg)31,360 / 14,22533,600 / 15,24117,857 / 8100
Engine Weight (lbs / kg)71,008 / 32,20980,640 / 36,57839,683 / 18,000
Tender Loaded Weight (lbs / kg)
Total Engine and Tender Weight (lbs / kg)
Tender Water Capacity (gals / ML)
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT)
Minimum weight of rail (calculated) (lb/yd / kg/m)52 / 2656 / 2830 / 15
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)78 / 198192 / 233796 / 243884 / 213484 / 2134
Boiler Pressure (psi / kPa)120 / 8.30160 / 1150 / 3.4050 / 3.4050 / 3.40
High Pressure Cylinders (dia x stroke) (in / mm)17" x 24" / 432x61018" x 26" / 457x66014" x 20" / 356x50812" x 16" / 305x40615" x 18" / 381x457
Tractive Effort (lbs / kg)9070 / 4114.0912,453 / 5648.591735 / 786.981166 / 528.892049 / 929.41
Factor of Adhesion (Weight on Drivers/Tractive Effort) 3.46 2.70 15.31
Heating Ability
Tubes (number - dia) (in / mm)252 - 1.626" / 41241 - 1.625" / 4196 - 1.625" / 41127 - 1.625" / 41113 - 2.25" / 57
Flues (number - dia) (in / mm)
Flue/Tube length (ft / m)11.33 / 3.45 9.33 / 2.84 8.50 / 2.59 8.58 / 2.62
Firebox Area (sq ft / m2)98 / 9.10130 / 12.0857.30 / 5.3352.35 / 4.8668.91 / 6.40
Grate Area (sq ft / m2)16.80 / 1.5619.20 / 1.7810.22 / 0.95 8.60 / 0.8014.15 / 1.32
Evaporative Heating Surface (sq ft / m2)1304 / 121.141250 / 116.17474 / 44.05511 / 47.47638 / 59.29
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)1304 / 121.141250 / 116.17474 / 44.05511 / 47.47638 / 59.29
Evaporative Heating Surface/Cylinder Volume206.82163.24133.02243.98173.30
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation20163072511430708
Same as above plus superheater percentage20163072511430708
Same as above but substitute firebox area for grate area11,76020,800286526183446
Power L144396087170725831868
Power MT312.06399.39318.90

Principal Dimensions by Steve Llanso of Sweat House Media

ClassFire FlyGazelleGreat BritainGreat WesternLion
Locobase ID659 10193 9062 2571 3031
RailroadGreat WesternGreat WesternGreat WesternGreat WesternGreat Western
CountryGreat BritainGreat BritainGreat BritainGreat BritainGreat Britain
Whyte2-2-22-2-2T2-2-22-2-22-2-2
Number in Class5653013
Road Numbers
Gauge7'7'7'7'7'
Number Built56513
BuilderseveralseveralGWRGWR - SwindonSharp, Roberts
Year18401841187118461838
Valve GearGabGabGoochGoochGab
Locomotive Length and Weight
Driver Wheelbase (ft / m)13.17 / 4.01
Engine Wheelbase (ft / m)20.33 / 6.2013.67 / 4.1719 / 5.7913.83 / 4.22
Ratio of driving wheelbase to overall engine wheelbase 0.65
Overall Wheelbase (engine & tender) (ft / m)39.33 / 11.99
Axle Loading (Maximum Weight per Axle) (lbs / kg)26,096 / 11,83723,632 / 10,719
Weight on Drivers (lbs / kg)26,096 / 11,83723,632 / 10,719
Engine Weight (lbs / kg)54,208 / 24,58856,840 / 25,78293,408 / 42,36964,96039,200 / 17,781
Tender Loaded Weight (lbs / kg)67,200 / 30,48133,600
Total Engine and Tender Weight (lbs / kg)56,840 / 25,782160,608 / 72,85098,560
Tender Water Capacity (gals / ML)2160 / 8.18540 / 2.053600 / 13.64
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) 1.70 / 2
Minimum weight of rail (calculated) (lb/yd / kg/m)43 / 21.5039 / 19.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)84 / 213472 / 182996 / 243896 / 243872 / 1829
Boiler Pressure (psi / kPa)50 / 3.4090 / 6.20140 / 9.70100 / 6.9050 / 3.40
High Pressure Cylinders (dia x stroke) (in / mm)15" x 18" / 381x45715" x 18" / 381x45718" x 24" / 457x61018" x 24" / 457x61014" x 18" / 356x457
Tractive Effort (lbs / kg)2049 / 929.414303 / 1951.819639 / 4372.186885 / 3122.992083 / 944.83
Factor of Adhesion (Weight on Drivers/Tractive Effort)12.74 5.49
Heating Ability
Tubes (number - dia) (in / mm)135 - 2" / 51120 - 2" / 51324 - 1.625" / 41278 - 2" / 51112 - 1.75" / 44
Flues (number - dia) (in / mm)
Flue/Tube length (ft / m)10.25 / 2.74 9.58 / 2.9211.44 / 3.4910.87 / 3.31 8.40 / 2.56
Firebox Area (sq ft / m2)97 / 9.0189.30 / 8.30153 / 14.22151 / 14.0351.17 / 4.76
Grate Area (sq ft / m2)13.40 / 1.2511.68 / 1.0924 / 2.2322.60 / 2.1011.66 / 1.08
Evaporative Heating Surface (sq ft / m2)829 / 77.04678 / 63.011751 / 162.731625 / 151.02479 / 44.52
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)829 / 77.04678 / 63.011751 / 162.731625 / 151.02479 / 44.52
Evaporative Heating Surface/Cylinder Volume225.18184.16247.72229.89149.36
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation670105133602260583
Same as above plus superheater percentage670105133602260583
Same as above but substitute firebox area for grate area4850803721,42015,1002559
Power L124983299797353871375
Power MT211.03307.76

Principal Dimensions by Steve Llanso of Sweat House Media

ClassNorth StarNorth Star - modifiedPolar StarPremierSun
Locobase ID657 10170 10186 10178 10188
RailroadGreat WesternGreat WesternGreat WesternGreat WesternGreat Western
CountryGreat BritainGreat BritainGreat BritainGreat BritainGreat Britain
Whyte2-2-22-2-22-2-22-2-22-2-2
Number in Class211221
Road Numbers 0 0 0
Gauge7'7'7'7'7'
Number Built21221
BuilderRobert Stephenson & CoRobert Stephenson & CoRobert Stephenson & CoMather & Dixonseveral
Year18371854183918381840
Valve GearGabGab
Locomotive Length and Weight
Driver Wheelbase (ft / m)
Engine Wheelbase (ft / m)13.33 / 4.0613.33 / 4.0613 / 3.9613.67 / 4.17
Ratio of driving wheelbase to overall engine wheelbase
Overall Wheelbase (engine & tender) (ft / m)21.75 / 6.6321.75 / 6.6321.75 / 6.63
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)
Engine Weight (lbs / kg)46,305 / 21,00446,305 / 21,004
Tender Loaded Weight (lbs / kg)
Total Engine and Tender Weight (lbs / kg)
Tender Water Capacity (gals / ML)
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT)
Minimum weight of rail (calculated) (lb/yd / kg/m)
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)84 / 213484 / 213484 / 213484 / 213472 / 1829
Boiler Pressure (psi / kPa)50 / 3.4075 / 5.2050 / 3.4050 / 3.4050 / 3.40
High Pressure Cylinders (dia x stroke) (in / mm)16" x 16" / 406x40616" x 18" / 406x45715.5" x 18" / 394x45714" x 14" / 356x35614" x 18" / 356x457
Tractive Effort (lbs / kg)2072 / 939.843497 / 1586.212188 / 992.461388 / 629.592083 / 944.83
Factor of Adhesion (Weight on Drivers/Tractive Effort)
Heating Ability
Tubes (number - dia) (in / mm)167 - 1.625" / 41167 - 1.75" / 44137 - 2" / 5196 - 1.625" / 41120 - 2" / 51
Flues (number - dia) (in / mm)
Flue/Tube length (ft / m) 8.50 / 2.59 9.90 / 3.02 8.42 / 2.57 8.75 / 2.67
Firebox Area (sq ft / m2)66.60 / 6.1994 / 8.7462.14 / 5.7841.71 / 3.8870.42 / 6.54
Grate Area (sq ft / m2)11.36 / 1.0611.76 / 1.0917.30 / 1.61 9.70 / 0.9013.60 / 1.26
Evaporative Heating Surface (sq ft / m2)711 / 66.08850 / 79662 / 61.52377 / 35.04617 / 57.34
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)711 / 66.08850 / 79662 / 61.52377 / 35.04617 / 57.34
Evaporative Heating Surface/Cylinder Volume190.96202.92168.40151.14192.39
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation568882865485680
Same as above plus superheater percentage568882865485680
Same as above but substitute firebox area for grate area33307050310720863521
Power L119633309173216431813
Power MT

Principal Dimensions by Steve Llanso of Sweat House Media

ClassSun - tankVulcanunknownunknown
Locobase ID10192 658 3511 9137
RailroadGreat WesternGreat WesternGreat WesternGreat Western
CountryGreat BritainGreat BritainGreat BritainGreat Britain
Whyte2-2-2T2-2-22-2-22-2-2
Number in Class21320
Road Numbers2
Gauge7'StdStdStd
Number Built320
BuilderseveralVulcan FoundryGWR - SwindonGWR - Swindon
Year1841183718751886
Valve GearGabStephensonStephenson
Locomotive Length and Weight
Driver Wheelbase (ft / m)
Engine Wheelbase (ft / m)13.67 / 4.1713.08 / 3.9917.50 / 5.3317.65 / 5.38
Ratio of driving wheelbase to overall engine wheelbase
Overall Wheelbase (engine & tender) (ft / m)
Axle Loading (Maximum Weight per Axle) (lbs / kg)23,632 / 10,71931,360 / 14,22534,496 / 15,647
Weight on Drivers (lbs / kg)23,632 / 10,71918,300 / 830131,360 / 14,22534,496 / 15,647
Engine Weight (lbs / kg)56,840 / 25,78239,700 / 18,00875,040 / 34,03878,401 / 35,562
Tender Loaded Weight (lbs / kg)59,360 / 26,92564,289 / 29,161
Total Engine and Tender Weight (lbs / kg)56,840 / 25,782134,400 / 60,963142,690 / 64,723
Tender Water Capacity (gals / ML)540 / 2.053120 / 11.823120 / 11.82
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) 2.20 / 2 3.30 / 3
Minimum weight of rail (calculated) (lb/yd / kg/m)39 / 19.5031 / 15.5052 / 2657 / 28.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)72 / 182984 / 213484 / 213484 / 2134
Boiler Pressure (psi / kPa)90 / 6.2050 / 3.40140 / 9.70140.70 / 9.70
High Pressure Cylinders (dia x stroke) (in / mm)15" x 18" / 381x45714" x 16" / 356x40618" x 24" / 457x61017.99" x 24.02" / 457x610
Tractive Effort (lbs / kg)4303 / 1951.811587 / 719.8511,016 / 4996.7811,068 / 5020.37
Factor of Adhesion (Weight on Drivers/Tractive Effort) 5.4911.53 2.85 3.12
Heating Ability
Tubes (number - dia) (in / mm)118 - 2" / 51144 - 1.875" / 48250 - 1.625" / 41
Flues (number - dia) (in / mm)
Flue/Tube length (ft / m) 9.08 / 2.77 8.41 / 2.5611 / 3.35
Firebox Area (sq ft / m2)90.34 / 8.4050.25 / 4.67133 / 12.36130.14 / 12.09
Grate Area (sq ft / m2)11.68 / 1.09 9.38 / 0.8718 / 1.6719.27 / 1.79
Evaporative Heating Surface (sq ft / m2)642 / 59.67703 / 65.311279 / 118.871250 / 116.17
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)642 / 59.67703 / 65.311279 / 118.871250 / 116.17
Evaporative Heating Surface/Cylinder Volume174.38246.61180.94176.89
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation105146925202711
Same as above plus superheater percentage105146925202711
Same as above but substitute firebox area for grate area8131251318,62018,311
Power L13208234353905298
Power MT299.27282.26378.92338.59

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