BRDatabase

From Trains Illustrated No 141 (June, 1960). Reproduced with the kind permission of Ian Allan Publishing Ltd

Technical details have at length been released of the North British Locomotive Co. Type "2" 1,100 h.p. B-B diesel-hydraulic locomotives being delivered to the Westem Region. The first six, Nos. D6300-5, are now described as prototypes, the production series comprising Nos. D6306-57. The N.B.L.- M.A.N. engine and Voith hydraulic trans- mission are based on those of which two are used on the N.B. Loco. Co. "Warship" class 2,000 h.p. locomotive.

Although the production version Type "2" follows the prototype in general construction, it features enhanced performance, thanks to a reduction in weight from 68 to 65 tons and an increase in power output from 1,000 h.p. to 1,100 h.p. Apart from some re-arrangement of auxiliary equipment, the principal difference noted is in the radiator fan operation: the electric fan drive and Drayton regulator temperature control employed on the prototypes have been superseded on the production version by Serck-Behr hydrostatic drive from an engine-driven pump with thermostatically controlled fan speed regulation.

The L12V18/21BS diesel engine drives through a Voith·N.B.L. LT306r hydraulic transmission and Hardy-Spicer cardan shafts to David Brown primary gearboxes on the inner axles of the bogies, from which a further cardan-shaft drive is taken to secondary gearboxes on the outer axles. Reversing gears are incorporated in the main hydraulic transmission unit and are operated by means of electro- pneumatic valves with a device to prevent reversal while the locomotive is moving. The transmission oil is cooled in a heat exchanger through which the cooling water is circulated, to assist rapid warming of the engine system and to bring engine and transmission into their true interdependence. Engines and hydraulic transmissions have been built in Glasgow under licence by the N.B. Loco. Co. The four-stroke 12-cylinder V-type engine of 180 mm. bore and 210 mm. stroke has a Napier exhaust-gas turbo-blower; maximum engine speed is 1,800 r.p.m. and the rated engine output is 1,100 b.h.p. at 1,530 r.p.m.

ln general the layout of the equipment is arranged around the hydraulic transmission, the output flanges of which need to be positioned symmetrically about the locomotive centre. The diesel engine is mounted forward of the transmission with the dynostarter coupled to an auxiliary drive at the rear of the transmission. The 450·gallon fuel tank is positioned high in the roof to give a gravity feed to the engine and is off-centre to allow a passageway on the left-hand side of the locomotive. The train-heating boiler is located at the rear of the fuel tank: Messrs. Robert Stephenson & Hawthorn are supplying Clayton steam generators for the first 20 locomotives and Messrs. Stone the boilers for the remaining 32 locomotives. A 500-gallon water tank for train-heating supply is suspended between the bogies.

The weight of the underframe, super- structure and equipment is borne on four side bearers, two per bogie, which have spherical contact surfaces to provide for changing track conditions. This weight is transferred through the bogie bolster to laminated springs suspended from the bogie frame by means of swing links and planks. No weight is taken through the bogie pivot, which deals only with pivoting, traction, braking and transverse forces. From the bogie frame the weight is transferred to the roller bearing axleboxes by compensating beams and coil springs; 26 of these locomotives have Timken axleboxes and 26 have S.K.F. axleboxes. Manganese steel liners are fitted on all axleboxes and horn guide faces.

Simplicity is the keynote of the control desk layout in the driving cabs, which are heated and provided with food lockers and cooking hotplates. The gauges on the driver`s desk are confined to a Smiths-Stone speedometer, Smiths vacuum gauge, brake pressure gauge and main reservoir pressure gauge. There is only one warning light to signal any fault on any of the three engines which may be operating, i.e., with three 1,100 h.p. locomotives in multiple or with one 1,100 h.p. locomotive in multiple with a 2,200 h.p. locomotive. On the left of the driver’s desk is the control for the train vacuum braking and in the centre the straight air brake for the locomotive only. The master controller governing power and the forward/reverse selector are at the driver’s right hand. The deadman’s control is a pedal on the driver’s side of the cab and a push-button on the opposite side; there is an alternative method of control by press-down handle on the driver’s side. The cab shell is fabricated by bolting together aluminium castings, whilst the side structure and roof are formed from Kynal sections, supplied by I.C.I., and aluminium sheeting.