LNER 2-6-4 Locomotives in Great_Britain

Class Details by Steve Llanso of Sweat House Media

Class L1 (Locobase 3123)

Data from Bryan Attewell ([] Steam locomotive simulator (April 2000 edition) and Richard Marsden's LNER site ([], firstviewed 2 September 2004, last accessed as [] on 13 August 2017). The LNER's Doncaster works (formerly those of the Great Northern) produced the prototype, the Darlington Works (ex-LNER, ex-North Eastern, ex-Stockton & Darlington) produced the next 29 in 1948, North British Locomotive Company added works numbers 26570-26604 in 1948-1949, and Robert Stephenson-Hawthorns completed the class with their works numbers 7500-7534 in 1949-1950.

John Firth ([], link unavailable in August 2017) noted that this Thompson design was meant to replace all the tank engines on the LNER. The prototype appeared in 1945, but series production only began in 1948.

Some observers pronounced them "good, all-around passenger locomotive". Steamindex noted their potent steaming capacity and their position is "among the most powerful passenger tanks in the United Kingdom". The design featured a relatively high-pressure boiler and 10" (254 mm) piston valves. 7,000 revenue miles (11,270 km) per month equalled many mainline locomotive designs.

"Unfortunately," Firth wrote, "they were not particularly successful". Blame largely falls on some under-design by Edward Thompson, but also, Locobase suspects, to post-war stringency systemwide.

Firth continued, "They steamed badly and required careful handling, otherwise they were unreliable. They were expensive to maintain, the axle bearings were inadequate for the loading and the wore out rapidly as well as the coupling rods and motion." The specs bear out the likelihood of poor steaming, showing an undersized boiler being worked very hard.

Steamindex distills at some length comments in two memoirs that describe signficant problems. E S Beavor, author of Steam Was My Calling (1974), that their considerable power "largely accounted for their frightful tendency to batter themselves loose after a few months of running." It was pretty bad, Beavor continued, "One could hear their high-speed knocking over a half-mile way", justifying the nickname "Concrete Mixers" at one shed. D W Harvey, in his "Bill Harvey's 60 Years of Steam (1986), cites a contemporary report by W G Thorley at the Neasden depot in 1950, which describes the self-same coupled axle boxes as "the worst for any recent design on any Region". A later retrofit of manganese-steel axle box liners increased total mileage between overhauls, which were averaging every 10 months.

Failures in welded tanks (most likely due to the same "concrete mixing" frame-shaking) and drivers that were too small for fast commuter traffic.

Even so, the design served as the basis for the British Railways Standard Class 4 Tank described in Locobasae 1481.

Fourteen of the locomotives were retired in 1960 when the Liverpool Line was electrified with the rest following in the next two years.

Principal Dimensions by Steve Llanso of Sweat House Media

Locobase ID3123
CountryGreat Britain
Number in Class100
Road Numbers9000-9003, E9004-E9015/67701-67800
Number Built100
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)
Engine Wheelbase (ft / m)34.50 / 10.52
Ratio of driving wheelbase to overall engine wheelbase
Overall Wheelbase (engine & tender) (ft / m)
Axle Loading (Maximum Weight per Axle) (lbs / kg)44,800 / 20,321
Weight on Drivers (lbs / kg)131,040 / 59,439
Engine Weight (lbs / kg)200,368 / 90,886
Tender Loaded Weight (lbs / kg)
Total Engine and Tender Weight (lbs / kg)200,368 / 90,886
Tender Water Capacity (gals / ML)2630 / 9.96
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT)5 / 5
Minimum weight of rail (calculated) (lb/yd / kg/m)73 / 36.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)62 / 1575
Boiler Pressure (psi / kPa)225 / 15.50
High Pressure Cylinders (dia x stroke) (in / mm)20" x 26" / 508x660
Tractive Effort (lbs / kg)32,081 / 14551.71
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.08
Heating Ability
Tubes (number - dia) (in / mm)150 - 1.75" / 44
Flues (number - dia) (in / mm)22 - 5.25" / 133
Flue/Tube length (ft / m)12.17 / 3.71
Firebox Area (sq ft / m2)138.50 / 12.87
Grate Area (sq ft / m2)24.70 / 2.30
Evaporative Heating Surface (sq ft / m2)1337 / 124.26
Superheating Surface (sq ft / m2)284 / 26.39
Combined Heating Surface (sq ft / m2)1621 / 150.65
Evaporative Heating Surface/Cylinder Volume141.42
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation5558
Same as above plus superheater percentage6558
Same as above but substitute firebox area for grate area36,772
Power L111,277
Power MT569.17

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