British Rail Class D3/7

British Rail Class D3/7

LMS No. 7080 (from The Engineer, 19 Jan. 1940)
Type and origin
Power type Diesel-electric
Builder LMS Derby Works (mechanical)
English Electric Rugby (engine)
English Electric Bradford (electrical)
Order number LMS Lots 141 and 156[1]
Build date 1939–1942[2]
Total produced 40[2]
Specifications
Configuration 0-6-0 DE
UIC class C
Gauge 4 ft 8 1⁄2 in (1,435 mm)
Wheel diameter 4 ft 3 in (1.30 m)
Wheelbase 15 ft 3 in (4.65 m)
Length 31 ft 4.5 in (9.563 m)
Loco weight 7080–7099: 55.25 long tons (56.14 t),
7100–7119: 53.50 long tons (54.36 t)[3]
Fuel capacity 586 gallons main, 75-gallon service tank
Prime mover English Electric diesel 6-cylinder, 4-stroke
Traction motors English Electric, 1 off
Performance figures
Maximum speed 20 mph (32 km/h)
Power output Engine: 350 bhp (260 kW) @ 680 rpm
Tractive effort 35,000 lbf (160,000 N)
Career
Operators London, Midland and Scottish Railway,
British Railways
Class LMS: 0F, BR: D3/7; later 3/8 and 3/8B
Numbers LMS:7080–7119;[2]
BR: 12003–12032[2]
Axle load class 7080–7099: RA 7,
7110–7119: RA 6
Withdrawn 1964(1), 1966–1967[2]
Source : The Engineer, 14 July 1939, except where noted

The British Railways Class D3/7 were a class of 0-6-0 diesel electric shunting locomotives built as LMS Nos. 7080–7119. The class were May 1939 through to July 1942 by the London, Midland and Scottish Railway at their Derby Works using a diesel electric transmission supplied by English Electric.

They were a modified version of the 1934-vintage Class D3/6 (LMS 7069-7079) diesel shunters based on the English Electric 6K diesel engine of 350 horsepower (260 kW), but had jackshaft transmission necessitating a significant increase in body length. The D3/6 had two axle-hung traction motors instead, and this feature became commonplace in more modern designs built after World War II.

Design

The locomotives were built to the specifications of LMS CME W.A. Stanier for general and hump shunting at the company's Derby Works using engine and electric equipment supplied by the English Electric Company.[4]

The locomotive's mechanical transmission consisted of a single, frame-mounted traction motor powering a jackshaft drive via a reduction gear; the jackshaft drove all three driving axles via connecting rod and coupling rods.[4]

The locomotive had an inner main frame similar to steam engine practice, with the axles supported by springs attached to the frame by tensioned rods, the center axle had 0.5 in (13 mm) side play.[4] The jackshaft was mounted in horn guides with the reduction gear totally enclosed on the left side of the locomotive.[5]

The engine and generator was supported on girders attached to the main frame via a three-point suspension with rubber vibration absorbing pads; the generator was to the rear of the engine. The locomotive body was compartmentalised, with side doors and a sliding roof allowing access.[4] Cooling was by a front mounted radiator, with belt driven fan cooling.[6]

The main generator was a 250 kW (340 hp) direct current machine. Main control was via notched engine speed control (350, 465, 590, and 680 rmp), with finer control via secondary lever.[6][7] The engine was fitted with a governor preventing overspeed, and electric overload protection. An 80-volt battery was used to energise the main generator, as well powering the electric control system and lights, and was also used to start the engine with the generator in motor mode; the battery was automatically charged when the engine was idling. An air compressor was powered via a belt drive from the generator via a belt drive; compressed air-operated Westinghouse double-wheel tread brakes, as well as sanding equipment and the whistle.[6]

The locomotive was unusual in that most other English Electric diesel shunters (e.g. British Rail Class D3/6) had two axle-hung traction motors.

History and numbering

Initially 20 of the type were ordered on Lot 141 with a number of the new design put into operation at Toton sidings by mid 1939.[4] An order for a further 20 units was placed on Lot 156 in 1939.[7] These forty locomotives were given LMS numbers 7080–7119.[2]

Ten (7100–7109[2]) were loaned to the War Department in 1941, and sold to the WD the following year. All ten survived the war; six were then sold to Egyptian Railways and four to Italian State Railways (Ferrovie dello Stato—FS) where they were matriculated as Class Ne.700.[8]

The other 30 stayed remained in Britain and later became British Railways numbers 12003–12032. One, 12030 was withdrawn in 1964, with the remainder withdrawn during 1966/67, before TOPS classes were allocated.[2]

See also

References

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