LNER 2-8-2 Locomotives in Great_Britain


Class Details by Steve Llanso of Sweat House Media

Class P1 (Locobase 2349)

Data from 1943 diagram supplied by Ian ("supergoods") in the UK Trainsim forum at [], last accessed 11 March 2013.

Designed by Nigel Gresley. The trailing truck had the unusual (in British practice) feature of holding a booster--two 10" x 12" cylinders that supplied an additional 9,500 lb starting tractive effort.

At the time they were delivered, the London & North Eastern was unable properly to serve them and only two were built. According to the anonymous history saved on Mike's Railway History website ([], visited November 2002), these engines could pull 100 coal wagons, each weighing 16 tons from Peterborough to London and return. "It is the problem of 'stowing' trains of this length in sidings and elsewhere, when they have to be passed by faster moving traffic, that make for difficulty in operation," says the observer. He added hopefully that if more freight wagons (sic) were fitted with a continuous brake system, railroads would realize the gain offered to line capacity by operating such long, heavy trains at higher speeds.


Class P2 (Locobase 2594)

Data from Richard Marsden's LNER Encyclopedia ([], last accessed 2 February 2010). See also Graham Nicholas's Design Study on the 2007 Prince of Wales website, which documents the construction of a modified P2 that began in 2013; last accessed 27 November 2017 at [].

Nigel Gresley's answer to the steep 1.34% gradients between Edinburgh and Aberdeen was this class of Mikados, the only 8-coupled express engines ever to run regularly in Great Britain. The first engine -- Cock o' the North -- used oscillating cams to open poppet valves. The succeeding five used Gresley's more conventional Gresley-Holcroft 2:1 conjugating lever to actuate the inside valve from the outside Walschaerts gear; all three cylinders were served by 9" piston valves. (See Locobase 2417 for a detailed description of this valve gear.)

The last four had longer combustion chambers that increased the firebox heating surface to a substantial 253 sq ft. The last five -- Earl Marischal, Lord President, Mons Meg, Thane of Fife, Wolf of Badenoch -- had a streamline casing that resembled that of the A4 Pacifics.

These engines were not entirely successful, being maintenance hungry because of bearing surfaces that were too small and a pony truck design that inflicted heavy wear on the Scottish curves. Even so, Glover (1967) comments that "...it is much to be regretted that they were not extensively multiplied."

Far from duplicating the engines, Gresley's successor, Edward Thompson converted the six into ugly, "somewhat contorted" (Glover's words) and unsatisfactory 4-6-2s during 1943-1944. They had an oddly long gap between the last bogie truck and the first driving axle. The result was constant frame flexing, especially on the line for which the P2s had originally been built. They had all been scrapped by 1961.

Taking their cue from the well-publicized "50th Peppercorn A1"Tornado project, the A1 Steam Locomotive Trust planners have modified the original design in several key respects.

Principal Dimensions by Steve Llanso of Sweat House Media

ClassP1P2
Locobase ID2349 2594
RailroadLNERLNER
CountryGreat BritainGreat Britain
Whyte2-8-22-8-2
Number in Class26
Road Numbers2001-2006
GaugeStdStd
Number Built26
BuilderLNERLNER
Year19251934
Valve GearWalschaertvarious
Locomotive Length and Weight
Driver Wheelbase (ft / m)18.50 / 5.6419.50 / 5.94
Engine Wheelbase (ft / m)36.17 / 11.0237.92 / 11.56
Ratio of driving wheelbase to overall engine wheelbase 0.51 0.51
Overall Wheelbase (engine & tender) (ft / m)64.08 / 19.53
Axle Loading (Maximum Weight per Axle) (lbs / kg)41,216 / 18,69544,800
Weight on Drivers (lbs / kg)160,048 / 72,597180,544 / 81,893
Engine Weight (lbs / kg)223,888 / 101,554247,520 / 112,273
Tender Loaded Weight (lbs / kg)115,360 / 52,326135,184
Total Engine and Tender Weight (lbs / kg)339,248 / 153,880382,704 / 112,273
Tender Water Capacity (gals / ML)5640 / 21.366000 / 22.73
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) 7.70 / 79 / 8
Minimum weight of rail (calculated) (lb/yd / kg/m)67 / 33.5075 / 37.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)62 / 157574 / 1880
Boiler Pressure (psi / kPa)180 / 12.40220 / 15.20
High Pressure Cylinders (dia x stroke) (in / mm)20" x 26" / 508x660 (3)21" x 26" / 533x660 (3)
Tractive Effort (lbs / kg)38,497 / 17461.9743,462 / 19714.06
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.16 4.15
Heating Ability
Tubes (number - dia) (in / mm)168 - 2.25" / 57121 - 2.25" / 57
Flues (number - dia) (in / mm)32 - 5.25" / 13343 - 5.25" / 133
Flue/Tube length (ft / m)19 / 5.7919 / 5.79
Firebox Area (sq ft / m2)215 / 19.97252.50 / 23.47
Grate Area (sq ft / m2)41.25 / 3.8350 / 4.65
Evaporative Heating Surface (sq ft / m2)2930 / 272.202598 / 241.45
Superheating Surface (sq ft / m2)525 / 48.77749 / 69.61
Combined Heating Surface (sq ft / m2)3455 / 320.973347 / 311.06
Evaporative Heating Surface/Cylinder Volume206.62166.17
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation742511,000
Same as above plus superheater percentage853913,420
Same as above but substitute firebox area for grate area44,50567,771
Power L111,45118,399
Power MT630.94898.68

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