British Rail Class 42

British Rail Class 42 Warship

British Rail Warship Class 42 No. D832 'Onslaught' and train at Washford on the West Somerset Railway

Type and origin Power type Diesel-hydraulic Builder British Railways' Swindon Works Build date 1958–1961 Total produced 38

Specifications Configuration: ​  • Whyte B–B  • AAR B-B  • UIC B'B' Gauge 4 ft 8 1⁄2 in (1,435 mm) standard gauge Wheel diameter 3 ft 3 1⁄2 in (1.003 m) Minimum curve 4.5 chains (91 m) Wheelbase 48 ft 3 in (14.71 m) Length 60 ft 0 in (18.29 m) Width 8 ft 10 in (2.69 m) Height 12 ft 0 1⁄2 in (3.670 m) Loco weight 78 long tons (79.3 t; 87.4 short tons) Fuel capacity 800 imp gal (3,600 l; 960 US gal) Prime mover Bristol Siddeley Maybach MD650. 2 per locomotive. Engine type Diesel engine (2x) Displacement 64.5 L (3,940 cu in) Transmission Mekydro Hydraulic MU working ◆ White Diamond Train heating Steam Train brakes Vacuum

Performance figures Maximum speed 90 mph (145 km/h) Power output Engines: Maybach engines, 1,135 hp (846 kW) at 1530 rpm x 2 (D803-29, D831-32 & D866-70), or 1,035 hp (772 kW) at 1400 rpm × 2 (D800 to 802). Tractive effort Maximum: 48,200 lbf (214 kN)

Career Operators British Railways Numbers D800–D832, D866–D870 Nicknames Warships Axle load class Route availability 7 (RA 6 from 1969) Retired 1968–1972 Disposition Two preserved, remainder scrapped

Bristol Siddeley Maybach MD650.

British Railways' (BR) Type 4 Warship class diesel-hydraulic locomotives were introduced in 1958. It was apparent at that time that the largest centre of expertise on diesel-hydraulic locomotives was in West Germany. The Western Region of British Railways negotiated a licence with German manufacturers to scale down the German Federal Railway's "V200" design to suit the smaller loading gauge of the British network, and to allow British manufacturers to construct the new locomotives. The resultant design bears a close resemblance, both cosmetically, and in the engineering employed, to the original V200 design. Warship locomotives were divided into two batches: those built at BR's Swindon works were numbered in the series D800 to D832 and from D866 to D870, had a maximum tractive effort of 52,400 pounds-force (233,000 N) and eventually became British Rail Class 42. 33 others, D833–865, were constructed by the North British Locomotive Company and became British Rail Class 43. They were allocated to Bristol Bath Road, Plymouth Laira, Newton Abbot and Old Oak Common.

Two Class 42s are preserved, D821 and D832.

The Western Region of British Railways had decided upon hydraulic transmission with lightweight alloy construction for its new diesel locomotives to replace "King" and "Castle" class steam locomotives. This was partly because of the stiff gradients between Exeter and Plymouth on the Exeter to Plymouth line: to save fuel compared with hauling the additional weight of the locomotive up these gradients and allow an extra revenue-earning passenger coach to be added to the train.