LSWR G16 class

LSWR G16 class
Works photograph of LSWR G16 prototype No. 492 at Eastleigh, 1921. The locomotive is in photographic grey livery
Type and origin Power type Steam Designer Robert Urie Builder LSWR Eastleigh Works Build date 1921 Total produced 4
Specifications Configuration: ​  • Whyte 4-8-0T  • UIC 2′D h2t Gauge 4 ft 8 1⁄2 in (1,435 mm) Leading dia. 3 ft 7 in (1.092 m) Driver dia. 5 ft 1 in (1.549 m) Length 42 ft 10 1⁄4 in (13.06 m) Width 9 ft 2 in (2.79 m) Height 13 ft 1 3⁄8 in (4.00 m) Axle load 18.50 long tons (18.8 t) Adhesive weight 72.90 long tons (74.1 t) Loco weight 95.10 long tons (96.6 t) Fuel type Coal Fuel capacity 3.50 long tons (3.6 t) Water cap 2,000 imp gal (9,100 l; 2,400 US gal) Firebox:  • Firegrate area 27 sq ft (2.5 m2) Boiler pressure 180 psi (1.24 MPa) Heating surface:  • Tubes and flues 1,267 sq ft (117.7 m2)  • Firebox 139 sq ft (12.9 m2) Superheater: ​  • Type Eastleigh (later Maunsell)  • Heating area 231 sq ft (21.5 m2) Cylinders Two, outside Cylinder size 22 in × 28 in (559 mm × 711 mm)
Performance figures Tractive effort 33,991 lbf (151.20 kN) Factor of adh. 4.4 (with tanks and bunkers half full)
Career Operators London and South Western Railway → Southern Railway → British Railways Class LSWR / SR: G16 Power class SR: A BR: 7F, later 8F Numbers LSWR: 429–495 SR: E429–E495 → 429–495 BR: 30429–30495 Nicknames Black Tanks Withdrawn 1959–1962 Disposition All scrapped

The LSWR G16 class is a steam tank locomotive class of 4-8-0T wheel arrangement. It was designed by Robert Urie and introduced in 1921 specifically for heavy shunting over humps at Feltham marshalling yard, on the London and South Western Railway (LSWR). They were based upon Urie's previous S15 class freight design, and apart from several periods of operating elsewhere on the LSWR and Southern railway network, they remained at Feltham for most of their operational careers.

With the fast growth of the LSWR's London area goods traffic in the early years of the twentieth century, the company decided to construct a modern gravitational marshalling yard at Feltham. This location gave excellent access to the company main lines as well as direct links to the Great Western Railway and London and North Western Railway, and to the Midland Railway, Great Northern Railway and Great Eastern Railway via the North London Line. Although completion of Feltham yard was delayed by the First World War, it was completed soon after. A new design of locomotive was required to haul heavy freight trains over the various flyovers that large marshalling yards such as Feltham had.

Urie had designed four very large shunting tanks based on his S15 goods 4-6-0s, except for utilising a somewhat smaller boiler, and eight-coupled wheels of 5 feet 1 inch (1.549 m) diameter for extra traction. Urie's design resulted in massive locomotives that weighed in at 95 tons, and were the most powerful locomotives on the LSWR system. When passed over to Southern Railway ownership, the new Chief Mechanical Engineer Richard Maunsell gave consideration to constructing more G16 locomotives, but instead decided to develop his SR Z Class 0-8-0T. Originally it had been intended to use them for transfer and trip workings so superheating was provided. Originally these were the Eastleigh design of superheater, but in later years these were replaced by the Maunsell pattern. This turned out to be a hindrance to the shunting activities and most of the transfer and trip workings were assigned to the similar H16 class of 4-6-2 tanks. The G16 and H16 classes shared many components of the same design, such as boilers and fireboxes. The G16s, along with the T14s and H16s, were the widest standard gauge steam locomotives ever to run in Britain.