Data from Bryan Attewell ([] Steam locomotive simulator (April 2000 edition), confirmed and augmented by Richard Marsden's LNER site -- [] (Jan 2004)
Tufnell (1986) says this batch was a scaled-down A5 design with smaller boilers to fit the LNER's North Eastern lines' loading gauge. See the earlier locomotives at Locobase 2323.
The data show a design consistent with British practice -- a hard-worked boiler, low superheat, generous firebox area, and a modest EHS to cylinder volume ratio.
As with the older 9N/A5, these locomotives provided solid service right through the 1950s. As newer designs replaced them in the mid-1950s, A5s retired, but the last didn't go out of service until 1960
Data from Bryan Attewell ([] Steam locomotive simulator (April 2000 edition), corrected and supplemented by [], last accessed 10 May 2008; and "0-8-0 Freight Engine-Power Class 3 MT" diagram from LMS Drawing Office Derby" from Ex-LMS Locomotives diagram compilation by David Faulkner supplied in July 2025 by Allen Stanley from his extensive Rail Data Exchange collection. See also Graham Glover, British Locomotive Design 1825-1960 (London: George Allen & Unwin Ltd, 1967).
Glover worte that this is Sir Henry Fowler's update of a London & North Western mineral engine that used a Belpaire boiler like its predecessor. It was that engine, he says, that was the last inside-cylinder 0-8-0s produced in Great Britain.
A photograph (seen at [], visited Nov 2002) shows a stolid, straight-barrelled, high-pitched boiler with a tiny stack and dome, heavy plate frame, and six1-wheeled tender with outside springs. Heating surface area later was reduced by 32 sq ft (2.9 sq m) to 1,402 sq ft with a commensurate reduction in superheater area of 15 sq ft (1.4 sq m) to 338 sq ft.
Steamindex's compilation -- [] (seen 20 October 2004) -- reveals to Locobase that this class was called the "Austin Sevens". Moreover, steamindex cites Bill Aves's article "The LMS 7F 0-8-0s - 'Austin Sevens': unnecessary and Perverse? Br. Rlys ill, 1995, 4, 358-67. and summarizes: "Despite having long travel valves and inside Walschaerts valve gear and a boiler based on that of the LNWR 0-8-0s the design was unsatisfactory due to a long wheel base coupled with inferior Derby axleboxes and bearings which were always running hot. Aves argues that the LMS should have made better use of the ROD 2-8-0s which it had purchased."
Steamindex quoted WG Thorley's book A Breath of Steam about the mechanical breakdowns this class suffered: "connecting rod little end bush wear was very heavy, it was impossible to keep gudgeon pin nuts tight for more than a few days, and longitudinal fractures developed in the gudgeon pins themselves."
Thorley added, however: "It redeemed itself only by good steaming qualities and efficient use of the steam when in service."
According to [] (Nov 2002, data from []), the production batches ran as follows:
Lot Year Engine #s
57 1928 49500-49599
71 1930 49600-49619
81 1931 49620-49659
84 1932 49660-49674
First withdrawals came in 1949 and continued until the last two retired in 1961.
| Principal Dimensions by Steve Llanso of Middle Run Media | ||
|---|---|---|
| Class | Class 7 | Class 7F |
| Locobase ID | 3763 | 3762 |
| Railroad | LMS | LMS |
| Country | Great Britain | Great Britain |
| Whyte | 0-8-0 | 0-8-0 |
| Number in Class | 175 | |
| Road Numbers | 9600-9774 | |
| Gauge | Std | Std |
| Number Built | 175 | |
| Builder | L&NW - Crewe | |
| Year | 1929 | |
| Valve Gear | Stephenson | Walschaert |
| Locomotive Length and Weight | ||
| Driver Wheelbase (ft / m) | 18.25 / 5.56 | |
| Engine Wheelbase (ft / m) | 18.25 / 5.56 | |
| Ratio of driving wheelbase to overall engine wheelbase | 1 | |
| Overall Wheelbase (engine & tender) (ft / m) | 41.85 / 12.76 | |
| Axle Loading (Maximum Weight per Axle) (lbs / kg) | 39,984 / 18,136 | |
| Weight on Drivers (lbs / kg) | 132,720 / 60,201 | 136,080 / 61,725 |
| Engine Weight (lbs / kg) | 132,720 / 60,201 | 136,080 / 61,725 |
| Tender Loaded Weight (lbs / kg) | 92,288 / 41,861 | |
| Total Engine and Tender Weight (lbs / kg) | 228,368 / 103,586 | |
| Tender Water Capacity (gals / ML) | 3500 / 13.26 | 4200 / 15.91 |
| Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) | 4.50 / 4 | 4.50 / 4.10 |
| Minimum weight of rail (calculated) (lb/yd / kg/m) | 55 / 27.50 | 57 / 28.50 |
| Geometry Relating to Tractive Effort | ||
| Driver Diameter (in / mm) | 56.50 / 1435 | 56.50 / 1435 |
| Boiler Pressure (psi / kPa) | 190 / 1310 | 200 / 1360 |
| High Pressure Cylinders (dia x stroke) (in / mm) | 21" x 28" / 533x711 | 19.5" x 26" / 495x660 |
| Tractive Effort (lbs / kg) | 35,296 / 16010.02 | 29,747 / 13493.03 |
| Factor of Adhesion (Weight on Drivers/Tractive Effort) | 3.76 | 4.57 |
| Heating Ability | ||
| Tubes (number - dia) (in / mm) | 120 - 2" / 51 | |
| Flues (number - dia) (in / mm) | 24 - 5" / 127 | |
| Flue/Tube length (ft / m) | 12.25 / 3.73 | 14.75 / 4.50 |
| Firebox Area (sq ft / m2) | 150 / 13.94 | |
| Grate Area (sq ft / m2) | 28.40 / 2.64 | 23.60 / 2.19 |
| Evaporative Heating Surface (sq ft / m2) | 1468 / 136.43 | 1540 / 143.07 |
| Superheating Surface (sq ft / m2) | 347 / 32.25 | 338 / 31.40 |
| Combined Heating Surface (sq ft / m2) | 1815 / 168.68 | 1878 / 174.47 |
| Evaporative Heating Surface/Cylinder Volume | 130.78 | 171.36 |
| Computations Relating to Power Output (More Information) | ||
| Robert LeMassena's Power Computation | 5396 | 4720 |
| Same as above plus superheater percentage | 6421 | 5570 |
| Same as above but substitute firebox area for grate area | 35,400 | |
| Power L1 | 11,174 | |
| Power MT | 724.12 | |