LMS/BR Class 4 2-6-4T locomotives

The London, Midland and Scottish Railway and British Railways Class 4 2-6-4T was a family of classes of steam locomotives. A grand total of 800 engines were built to five separate designs by four different mechanical engineers, over a period of 29 years. Each new design was a development of the previous one. The LMS gave the whole family the power classification 4P, BR 4MT. It is therefore worth considering them as a group as follows:

LMS Nos BR Nos Design Designer Built Built by LMS Built by BR Total built
2300–2424 42300–42424 Fowler Henry Fowler 1927–1934 125 0 125
2500–2536 42500–42536 Stanier, 3 cylinder William Stanier 1934 37 0 37
2425–2494, 2537–2672 42425–42494, 42537–42672 Stanier, 2 cylinder William Stanier 1935–1943 206 0 206
2187–2299, 2673–2699 42050–42299, 42673–42699 Fairburn Charles Fairburn 1945–1951 130 147 277
— 80000–80154 BR Standard Robert Riddles 1951–1956 0 155 155
Total 1927–1956 498 302 800

Withdrawal

All engines were withdrawn from stock between 1959 and 1967, summarised as follows:

Locomotives withdrawn by year
Year Fowler Stanier,
3-cylinder 		Stanier,
2-cylinder		Fairburn BR
Standard 		Total
1959 5 0 0 0 0 5
1960 11 1 2 0 0 14
1961 22 7 17 3 0 49
1962 37 29 43 43 1 153
1963 16 0 29 30 0 75
1964 20 0 51 57 31 159
1965 12 0 38 54 44 148
1966 2 0 11 48 54 115
1967 0 0 15 42 25 82
Total 125 37 206 277 155 800
Locomotives in service at year end
Year Fowler Stanier,
3-cylinder 		Stanier,
2-cylinder 		Fairburn BR
Standard 		Total
1958 125 37 206 277 155 800
1959 120 37 206 277 155 795
1960 109 36 204 277 155 781
1961 87 29 187 274 155 732
1962 50 0 144 231 154 579
1963 34 0 115 201 154 504
1964 14 0 64 144 123 345
1965 2 0 26 90 79 197
1966 0 0 15 42 25 82
1967 0 0 0 0 0 0

Technical comparison

For technical purposes, it is worth splitting the Fairburn tanks into two subclasses; early (42050–42146) and late (42147–42699) as their weights differ slightly.

Attribute Fowler Stanier, 3 cylinder Stanier, 2 cylinder Fairburn (early)[lower-alpha 1] Fairburn (late)[lower-alpha 2] BR Standard
Leading wheel diameter 3 ft 3 1⁄2 in (1.003 m) 3 ft 0 in (0.914 m)
Driving wheel diameter 5 ft 9 in (1.753 m) 5 ft 8 in (1.727 m)
Trailing wheel diameter 3 ft 3 1⁄2 in (1.003 m) 3 ft 0 in (0.914 m)
Wheelbase 38 ft 6 in (11.73 m) 37 ft 1 in (11.30 m) 36 ft 10 in (11.23 m)
Length 47 ft 2 3⁄4 in (14.40 m) 45 ft 9 3⁄4 in (13.96 m) 44 ft 9 7⁄8 in (13.66 m)
Weight 86.25 long tons (87.63 t) 92.25 long tons (93.73 t) 87.75 long tons (89.16 t) 85.25 long tons (86.62 t) 84.70 long tons (86.06 t) 86.50 long tons (87.89 t)
Axleload 17.95 long tons (18.24 t)
Coal capacity 3.50 long tons (3.56 t)
Water capacity 2,000 imp gal (9,100 l) 1,875 imp gal (8,500 l) 2,000 imp gal (9,100 l)
Boiler G8AS 4C ABR5
Boiler pressure 200 psi (1.38 MPa) 200 psi (1.38 MPa) 225 psi (1.55 MPa)
Firegrate area 25 sq ft (2.3 m2) 25 sq ft (2.3 m2) 26.7 sq ft (2.48 m2)
Heating surface: Tubes 1,082 sq ft (100.5 m2) 1,011 sq ft (93.9 m2) 1,223 sq ft (113.6 m2)
Heating surface: Firebox 138 sq ft (12.8 m2) 137 sq ft (12.7 m2) 143 sq ft (13.3 m2)
Superheater area 266 sq ft / 246 sq ft 160 sq ft/154 sq ft 240 sq ft (22 m2)
Cylinders 2 outside 3 2 outside 2 outside 2 outside 2 outside
Cylinder size 19 in × 26 in (483 mm × 660 mm) 16 in × 26 in (406 mm × 660 mm) 19.625 in × 26 in (498 mm × 660 mm) 18 in × 28 in (457 mm × 711 mm)
Tractive effort 23,125 lbf (102.87 kN) 24,598 lbf (109.42 kN) 24,671 lbf (109.74 kN) 25,515 lbf (113.50 kN)
  1. ↑ Derby Lots 177, 185, 186, and 196: locomotives 42147–42699, built 1945–1949
  2. ↑ Derby Lots 202, 210, and all Brighton-built locomotives: numbers 42050–42146, built 1948–1951

References