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 [] (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 | |
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Class | 4P-A |
Locobase ID | 3025 |
Railroad | LMS |
Country | Great Britain |
Whyte | 4-4-0 |
Number in Class | 200 |
Road Numbers | 1045-1199, 900-939/41045-41099, 40900-40939 |
Gauge | Std |
Number Built | 200 |
Builder | Derby |
Year | 1924 |
Valve Gear | Stephenson |
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 Volume | 308.72 |
Computations Relating to Power Output (More Information) | |
Robert LeMassena's Power Computation | 5680 |
Same as above plus superheater percentage | 6702 |
Same as above but substitute firebox area for grate area | 34,763 |
Power L1 | 12,104 |
Power MT | 607.80 |