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British Rail Class 24
The British Rail Class 24 diesel locomotives, originally known as the Sulzer Type 2, were built from 1958 to 1961. 151 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The final survivor, no. 24081, was withdrawn from Crewe depot in 1980.
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 CIÉ 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.
The original pilot scheme locomotives (D5000–D5019) were fitted with a Stone Vapor type OK4646A steam heating boiler with a 600 imperial gallons (2,700 litres; 720 US gallons) water tank. The following ten locomotives had the similar 1,750 pounds (790 kg) per hour type OK4616B and a reduced water capacity of 450 imperial gallons (2,000 litres; 540 US gallons), and this was perpetuated in the remaining production run which used the Stone Vapour 1,000 pounds (450 kg) per hour type L4610 boiler. These variations meant that the initial batch of 20 locomotives weighed 79 long tons 16 hundredweight (81.1 t; 89.4 short tons), the following 10 locomotives slightly less at 78 long tons 16 hundredweight (80.1 t; 88.3 short tons), the remaining Class 24/0 at 77 long tons (78 t; 86 short tons), and the Class 24/1 at exactly 73 long tons (74 t; 82 short tons). During subsequent years the boilers were removed from the majority of Class 24/1 locomotives, reducing the overall weight by 2 long tons (2.03 t; 2.24 short tons). Ten locomotives (D5102–5111) had no train heating, the space being occupied by the air compressors needed for operating the Consett iron ore trains.
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 locomotive 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 locomotives 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 locomotives 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 and on the Highland Main Line from Perth to 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.
The pilot scheme locomotives were delivered in overall green livery with a grey roof and black below the body. D5000 was delivered with a narrow light grey stripe at waist level while the remainder had a broad light grey stripe at solebar level. This light grey stripe may have appeared bluish and has been described as pale blue or eggshell, but in most illustrations, it appears to be off-white. At first, green liveried locomotives had plain green ends, but this was changed from 1962 to small yellow warning panels, and then from 1967 to full yellow ends, some locomotives receiving these while still in green livery. At least five locomotives were repainted in two-tone green livery (applied along with the small yellow warning panel) in a similar manner to Class 47s and some Class 25s.
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British Rail Class 24 AI simulator
(@British Rail Class 24_simulator)
British Rail Class 24
The British Rail Class 24 diesel locomotives, originally known as the Sulzer Type 2, were built from 1958 to 1961. 151 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 final survivor, no. 24081, was withdrawn from Crewe depot in 1980.
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 CIÉ 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.
The original pilot scheme locomotives (D5000–D5019) were fitted with a Stone Vapor type OK4646A steam heating boiler with a 600 imperial gallons (2,700 litres; 720 US gallons) water tank. The following ten locomotives had the similar 1,750 pounds (790 kg) per hour type OK4616B and a reduced water capacity of 450 imperial gallons (2,000 litres; 540 US gallons), and this was perpetuated in the remaining production run which used the Stone Vapour 1,000 pounds (450 kg) per hour type L4610 boiler. These variations meant that the initial batch of 20 locomotives weighed 79 long tons 16 hundredweight (81.1 t; 89.4 short tons), the following 10 locomotives slightly less at 78 long tons 16 hundredweight (80.1 t; 88.3 short tons), the remaining Class 24/0 at 77 long tons (78 t; 86 short tons), and the Class 24/1 at exactly 73 long tons (74 t; 82 short tons). During subsequent years the boilers were removed from the majority of Class 24/1 locomotives, reducing the overall weight by 2 long tons (2.03 t; 2.24 short tons). Ten locomotives (D5102–5111) had no train heating, the space being occupied by the air compressors needed for operating the Consett iron ore trains.
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 locomotive 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 locomotives 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 locomotives 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 and on the Highland Main Line from Perth to 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.
The pilot scheme locomotives were delivered in overall green livery with a grey roof and black below the body. D5000 was delivered with a narrow light grey stripe at waist level while the remainder had a broad light grey stripe at solebar level. This light grey stripe may have appeared bluish and has been described as pale blue or eggshell, but in most illustrations, it appears to be off-white. At first, green liveried locomotives had plain green ends, but this was changed from 1962 to small yellow warning panels, and then from 1967 to full yellow ends, some locomotives receiving these while still in green livery. At least five locomotives were repainted in two-tone green livery (applied along with the small yellow warning panel) in a similar manner to Class 47s and some Class 25s.