Class 24 5081 Start Up And Ride Along And footage of other Locomotives. GWR 1/7/23

24 081 and few other surprises


The British Railways Class 24 diesel locomotives, also known as the Sulzer Type 2, were built from 1958 to 1961. One hundred and fifty-one were built at Derby, Crewe and Darlington, the first twenty of them as part of the British Railways 1955 Modernisation Plan. This class was used as the basis for the development of the Class 25 locomotives.

The main power for the class 24 was the Sulzer 6LDA28 diesel engine - denoting 6 cylinders; Locomotive use; Direct fuel injection; (turbo-charged); 28 cm (11 in) bore cylinders. This was effectively an off-the-shelf purchase with small changes to bearings, injectors and some other minor items. The same engine was used in the CIE 101 Class locomotives in Ireland.

The diesel engine powered another off-the-shelf product, the British Thomson-Houston (BTH) RTB15656 main generator which, in the class 24, was rated at 735 kW (986 hp), 750/525 V and 980/1400 A at 750 rpm. Traction motors, one per axle, were also by BTH being the type 137BY rated at 222 hp (166 kW), 525 V, 350 A at 560 rpm connected to the axle via a 16:81 gear stepdown ratio, each force ventilated by an AEI 12.2 hp (9.1 kW) electric motor.

Several of the systems within the class 24s were standard. The braking system was the standard BR system, adopted as part of the Modernisation Plan, of locomotive air and train vacuum brake, both applied by a single handle via a proportional valve. Similarly, the connection for multiple working was the standard electro-pneumatic system designated "Blue Star" with each loco bearing a small blue coloured 5-pointed star above each buffer to denote this. Also common was the provision of a door to allow staff to pass between locomotives, or between a locomotive and adjacent coach. In practice, these were rarely used and were sealed shut at overhaul during the 1970s to reduce draughts in the cab.

With production reaching 151 there were some differences between batches of locos too. Ten of the initial twenty had "Athermos" pressure-lubricated plain bearing axleboxes rather than the more usual roller-bearing axleboxes. Although these remained for the life of the locos they were the only ones so fitted. Much more noticeable were D5114–D5132 which were fitted with tablet catchers on the side of the driver's cab for use on the Far North Line from Inverness. Also very visible were the roof-mounted headcode boxes fitted from D5114 giving an outward appearance very similar to the later Class 25 but without horn grilles.