LMS 4-4-0 Locomotives in Great_Britain


Class Details by Steve Llanso of Sweat House Media

Class 4P-A (Locobase 3025)

See E S Cox, "A Modern Locomotive History-Ten Years' Development on the LMS - 1923-1932", Journal of the Institute of Locomotive Engineers, Paper No. 457, delivered 2 January 1946, p.114, and Ahrons (1927). See also Brian Hollingsworth, The Great Book of Trains (New York: Portland House, 1987), pp.76-77; and No 43: Superheated Passenger Engine and Tender for the London, Midland and Scottish Railway, The Vulcan Foundry Locomotive Works catalogue, archived at [link] (Many thanks to Jorge Cerezo Toledo for his 26 June 2021 email containing links to several sites including the Vulcan Catalogue referred to above.).

The Derby Works produced the first and the last batches, starting with 1045-1084 in 1924 and 1085-1114 in 1925 and ending with five more-935-939 in 1932. Horwich Works turned out 1115-11130 in 1925 and 1131-1134 in 1926. North British Locomotive Company delivered its only 4Ps as works numbers 23229-23253 in 1925. Vulcan Foundry supplied works numbers 3833-3857 in 1925. Its other batch came in 1927 with works numbers 3990-4047. (Road numbers ran 1185-1199, 900-909, 925-934, and 910-924.)

Deeley-type compound with one HP and two LP cylinders. So sound a design was the 1905 4-4-0 design as superheated by Fowler beginning in 1913 (Locobase 2271) that the London, Midland, & Scottish -- one of the groups formed in 1923 -- produced scores more at Derby in the 1920s.

They were delivered with 19 3/4 and 21 3/4" x 26" cylinders, but were soon relinered to match the dimensions of the original Midland engines. The HP cylinder used a piston valve, the LP cylinders tooks steam through slide valves. Among the few changes was a 3" (76.2 mm) reduction in driver diameter. Most likely due to different installations by different builders, locomotives had one of two superheater areas--the 291 sq ft shown in the specifications above and 272 sq ft (25.27 sq m).

Hollingsworth noted that the automatic valve that allowed the LP cylinders to work "simple" when the throttle was partly closed meant that the engines used more steam in that setting than when the throttle was fully open and the two cylinders worked as compounds. "Even so," he added, "the long-lived Midland Compound locomotives were considered to be reliable and useful machines. For the fast, frequent, but short trains of their parent Midland Railway, the 'Crimson Ramblers' were found to be adequate and economical."

Principal Dimensions by Steve Llanso of Middle Run Media
Class4P-A
Locobase ID3025
RailroadLMS
CountryGreat Britain
Whyte4-4-0
Number in Class200
Road Numbers1045-1199, 900-939/41045-41099, 40900-40939
GaugeStd
Number Built200
BuilderDerby
Year1924
Valve GearStephenson
Locomotive Length and Weight
Driver Wheelbase (ft / m) 9.60 / 2.93
Engine Wheelbase (ft / m)24.25 / 7.39
Ratio of driving wheelbase to overall engine wheelbase 0.40
Overall Wheelbase (engine & tender) (ft / m)
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)87,808 / 39,829
Engine Weight (lbs / kg)138,208 / 62,690
Tender Loaded Weight (lbs / kg)93,400 / 42,366
Total Engine and Tender Weight (lbs / kg)231,608 / 105,056
Tender Water Capacity (gals / ML)4200 / 15.91
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) 6.20 / 6
Minimum weight of rail (calculated) (lb/yd / kg/m)73 / 36.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)81 / 2057
Boiler Pressure (psi / kPa)200 / 1380
High Pressure Cylinders (dia x stroke) (in / mm)19" x 26" / 483x660 (1)
Low Pressure Cylinders (dia x stroke) (in / mm)21" x 26" / 533x660
Tractive Effort (lbs / kg)16,248 / 7369.98
Factor of Adhesion (Weight on Drivers/Tractive Effort) 5.40
Heating Ability
Tubes (number - dia) (in / mm)146 - 1.75" / 44
Flues (number - dia) (in / mm)21 - 5.25" / 133
Flue/Tube length (ft / m)12 / 3.66
Firebox Area (sq ft / m2)147.30 / 13.68
Grate Area (sq ft / m2)28.40 / 2.64
Evaporative Heating Surface (sq ft / m2)1317 / 122.35
Superheating Surface (sq ft / m2)291 / 27.03
Combined Heating Surface (sq ft / m2)1608 / 149.38
Evaporative Heating Surface/Cylinder Volume308.72
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation5680
Same as above plus superheater percentage6702
Same as above but substitute firebox area for grate area34,763
Power L112,104
Power MT607.80

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