Indian locomotive class SP

BESA class SP[1]
Builder's photo of an SP class.
Type and origin Power type Steam Designer British Engineering Standards Association (BESA) Builder Vulcan Foundry North British Locomotive Company Robert Stephenson and Hawthorns Build date SP: 1904 Total produced SP: 10
Specifications Configuration: ​  • Whyte 4-4-0 Gauge 5 ft 6 in (1,676 mm) Driver dia. 6 ft 2 in (1.880 m) Wheelbase 6 ft 0 in (1.829 m) + 7 ft 5 in (2.261 m) + 9 ft 5 in (2.870 m) Axle load 16.25 long tons (16.51 t; 18.20 short tons) Loco weight 51.00 long tons (51.82 t; 57.12 short tons) Tender weight 39.50 long tons (40.13 t; 44.24 short tons) Fuel type Coal Fuel capacity 7.5 long tons (7.6 t; 8.4 short tons) Water cap. 3,000 imp gal (14,000 L; 3,600 US gal) Firebox: ​  • Grate area 25.3 sq ft (2.35 m2) Boiler: ​  • Diameter Outside: 4 ft 8+1⁄2 in (1,435 mm)  • Tube plates 11 ft 4+1⁄4 in (3.46 m)  • Small tubes 1+3⁄4 in (44 mm) × 236 off Boiler pressure 180 lbf/in2 (1.24 MPa) Heating surface: ​  • Firebox 120 sq ft (11 m2)  • Tubes 1,229.5 sq ft (114.22 m2) Cylinders Two, inside Cylinder size 18+1⁄2 in × 26 in (470 mm × 660 mm) Valve gear Rotary Lentz valve gear Valve type Slide valve
Performance figures Tractive effort 11.2 bar boiler pressure: 87 kN 9.3 bar boiler pressure: 72 kN
Career Operators Indian Railways, Eastern Bengal Railway, East Indian Railway Company Oudh and Rohilkhand Railway Locale Eastern Railway zone and Northern Railway zone Disposition At least one preserved in the United Kingdom.

The Indian locomotive class SP is a class of Indian 4-4-0 passenger steam locomotives which was built around 1905. Its class designation, SP, stands for Standard Passenger. It was one of the BESA locomotives developed by the British Engineering Standards Committee, later called the British Engineering Standards Association (BESA).

The SP class was catalogued in the first edition of the 1903 BESA report on standard locomotives for the railways of the British Raj. 4-4-0 (American) locomotives were preferred in India as they had good riding qualities, even on poor track conditions.^{[citation needed]} The SP class used the same boiler as the SG class standard goods locomotives, which had a diameter of 4 feet 8+1⁄4 inches (1,429 mm). In the 1910 BESA report, a variant with a larger boiler was proposed, which had a diameter of 5 feet 1+1⁄4 inches (1,556 mm), as used in the PT class passenger tank locomotives.^[2]

The locomotives were delivered to different railways, but only the Indian States Railways (ISR)-operated railways used the class designation SP. Beyer Peacock delivered 10 locomotives to the North Western Railway (NWR), whose route network lay in today's border area of India and Pakistan.^[3]

The locomotives were designed with two cylinders, a Belpaire firebox, and used saturated steam. The grate was arranged between the coupled wheel sets. Between the frames were the two cylinders and the Walschaerts valve gear. A small pilot was fitted to the locomotive's buffer beam. The cab was completely enclosed, with the cab's rear wall being formed by the three-axle tender.

A later version was designed with a superheater and designated SPS (Standard Passenger, Superheated); SP locomotives retro-fitted with superheaters were usually reclassified as SPC (Standard Passenger, Converted). An SPS locomotive, most recently operated by Pakistan Railways under road number 3157, is preserved in the Museum of Science and Industry (MOSI) in Manchester. The exterior of the locomotive is practically identical to that of the SP class.

• Indian Railways
• Rail transport in India#History
• Locomotives of India
• Rail transport in India

• Hughes, Hugh (1990). Indian Locomotives: Part 1 – Broad Gauge 1851–1940. Harrow, Middlesex: The Continental Railway Circle. ISBN 0-9503469-8-5. OCLC 21871114.

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