LNWR Precursor Tank Class

The London and North Western Railway (LNWR) Precursor Tank Class was a class of 4-4-2 tank steam locomotives. Fifty were built to the design of George Whale between 1906 and 1909, being a tank engine version of his Precursor Class.

LNWR Precursor Tank
No. 528 in photographic grey livery
Type and origin Power type Steam Designer George Whale Build date 1906–1909 Total produced 50
Specifications Configuration: ​  • Whyte 4-4-2T  • UIC 2′B1 2t Gauge 4 ft 8 1⁄2 in (1,435 mm) Leading dia. First 30: 3 ft 9 in (1.143 m) Last 20: 3 ft 3 in (0.991 m) Driver dia. 6 ft 3 in (1.905 m) Trailing dia. First 30: 3 ft 9 in (1.143 m) Last 20: 3 ft 3 in (0.991 m) Loco weight 74 long tons 15 cwt (167,400 lb or 75.9 t) Boiler pressure 175 psi (1.21 MPa) Cylinders Two, inside Cylinder size 19 in × 26 in (483 mm × 660 mm) Valve gear Joy
Performance figures Tractive effort 15,216 lbf (67.68 kN)
Career Operators LNWR » LMS Power class LMS: 2P Withdrawn 1927–1940 Disposition All scrapped

The first thirty had 3 ft 9 in (1.143 m) carrying wheels, the latter twenty had 3 ft 3 in (0.991 m) carrying wheels. The LNWR reused numbers from withdrawn locomotives, so the numbering system was completely haphazard. The 3 ft 9 in engines were numbered by 528, 531, 784, 1295, 1305, 1981–1985, 97, 111, 181, 196, 562, 616, 803, 1356, 1508, 2210, 139, 653, 834, 874, 1506, 1572, 1589, 1671, 1714, and 2165. The 3 ft 3 in engines were numbered 44, 527, 612, 762, 827, 875, 1427, 1764, 2196, 2446, 920, 935, 1164, 1219, 1523, 1536, 1551, 2077, 2223 and 2228.

All fifty passed into LMS ownership in 1923. The LMS gave them the power classification 2P. The LMS also renumbered them into solid block of numbers: 6780–6809 for the 3 ft 9 in engines and 6810–6829 for the 3 ft 3 in engines, in the order given above.

They were withdrawn between 1927 and 1940. None were preserved.