British Railways 2-6-4 Locomotives in Great_Britain

Class Details by Steve Llanso of Sweat House Media

Class Class 4MT (Locobase 1481)

Data from "BR Standard Class 4 2-6-4T", Wikipedia at [], last accessed 21 February 2021. (Thanks to Patrick Shivley for his 17 May 2021 email correcting the class ID.)

Developed as part of the range of twelve Standard engine designs that entered British Railway service in the 1950s. RA Riddles drew from a variety of sources, basing this tank engine on Stanier's 1934 LMS design (Locobase 3576). The Class 4's boiler was similar to the 4-6-0 Standard Class 4, however, although it had fewer and shorter flues and tubes.

Commentary at [] (no longer active) notes that a side effect of changing the details (shrinking the cylinders from Stanier's 19" (483 mm) and increasing the boiler pressure, e.g.) was aesthetic: "...a much more handsome locomotive than the relatively workaday appearance of the LMS engines. They seem to have been better liked by their crews, too, probably for their more comfortable cabs, freer running, and more economical operation."

Glover (1967) notes that their relatively high axle loading of 40,208 lb led to a set of smaller 2-6-2T locomotives.

First withdrawals from service came in 1964 and were completed in 1967.

Principal Dimensions by Steve Llanso of Sweat House Media

ClassClass 4MT
Locobase ID1481
RailroadBritish Railways
CountryGreat Britain
Number in Class155
Road Numbers80000-80154
Number Built155
BuilderBritish Rail
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)15.33 / 4.67
Engine Wheelbase (ft / m)36.83 / 11.23
Ratio of driving wheelbase to overall engine wheelbase 0.42
Overall Wheelbase (engine & tender) (ft / m)
Axle Loading (Maximum Weight per Axle) (lbs / kg)40,208 / 18,238
Weight on Drivers (lbs / kg)118,720 / 53,851
Engine Weight (lbs / kg)198,420 / 90,002
Tender Loaded Weight (lbs / kg)
Total Engine and Tender Weight (lbs / kg)198,420 / 90,002
Tender Water Capacity (gals / ML)24 / 0.09
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) 4.40 / 4
Minimum weight of rail (calculated) (lb/yd / kg/m)66 / 33
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)68 / 1727
Boiler Pressure (psi / kPa)225 / 15.50
High Pressure Cylinders (dia x stroke) (in / mm)18" x 28" / 457x711
Tractive Effort (lbs / kg)25,515 / 11573.42
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.65
Heating Ability
Tubes (number - dia) (in / mm)157 - 1.75" / 44
Flues (number - dia) (in / mm)21 - 5.375" / 137
Flue/Tube length (ft / m)12.25 / 3.73
Firebox Area (sq ft / m2)143 / 13.29
Grate Area (sq ft / m2)26.70 / 2.48
Evaporative Heating Surface (sq ft / m2)1366 / 126.91
Superheating Surface (sq ft / m2)240 / 22.30
Combined Heating Surface (sq ft / m2)1606 / 149.21
Evaporative Heating Surface/Cylinder Volume165.64
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation6008
Same as above plus superheater percentage6909
Same as above but substitute firebox area for grate area37,001
Power L113,114
Power MT730.58

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