The Indian locomotive class XP was a class of experimental "Pacific" type steam locomotives used on broad gauge lines in India. The two members of the class were built by

Vulcan Foundry The Vulcan Foundry Limited was an English locomotive builder sited at Newton-le-Willows, Lancashire (now Merseyside). History The Vulcan Foundry opened in 1832, as Charles Tayleur and Company to produce girders for bridges, switches, crossin ...

in Newton-le-Willows,

Lancashire Lancashire ( , ; abbreviated Lancs) is the name of a historic county, ceremonial county, and non-metropolitan county in North West England. The boundaries of these three areas differ significantly. The non-metropolitan county of Lancash ...

, England, to an order placed by the

Great Indian Peninsula Railway The Great Indian Peninsula Railway (reporting mark GIPR) was a predecessor of the Central Railway (and by extension, the current state-owned Indian Railways), whose headquarters was at the Boree Bunder in Mumbai (later, the Victoria Terminu ...

(GIPR) in 1935.

Background

The class XP was intended to have the power of the class XC heavy passenger Pacific locomotives, but the operating area of the light

axle load An axle or axletree is a central shaft for a rotating wheel or gear. On wheeled vehicles, the axle may be fixed to the wheels, rotating with them, or fixed to the vehicle, with the wheels rotating around the axle. In the former case, bearin ...

class XB Pacifics. The performance objectives set for the class XP were running mileages of between overhauls, and a monthly average mileage of . Both of these objectives were very ambitious for the time.

Design details

The basis for the class XP design was the boiler and firebox of the XB, with some modification to their details. The wheels and cylinders of the two classes had the same dimensions. The XP's boiler pressure was higher, and its tractive effort was greater, than those of both the XB and the XC. Both class XP locomotives were fitted with

Caprotti valve gear The Caprotti valve gear is a type of steam engine valve gear invented in the early 1920s by Italian architect and engineer Arturo Caprotti. It uses camshafts and poppet valves rather than the piston valves used in other valve gear. While basin ...

, and

roller bearings In mechanical engineering, a rolling-element bearing, also known as a rolling bearing, is a bearing which carries a load by placing rolling elements (such as balls or rollers) between two concentric, grooved rings called races. The relative m ...

on all engine and tender wheels. The class leader's bearings were supplied by Timken, and its class mate's bearings were by Skefco. In 1946, when the Indian government ordered the 16 class WP prototypes, their design was based on that of the class XP. Hughes 1996, p. 12.

Service history

The class XP locomotives entered service with the GIPR in 1937, as nos. 3100 and 3101. The class leader was named '' King George'', in honour of the then King-Emperor of India, and the other class XP engine was named '' Queen Elizabeth'', after the then Queen-Empress. In November 1951, the GIPR was incorporated into the

Central Railway zone Central Railway (abbreviated CR) is one of the 19 zones of Indian Railways. Its headquarters is in Mumbai at Chhatrapati Shivaji Maharaj Terminus. It has the distinction of operating the first passenger railway line in India, which opened from M ...

of the

Indian Railways Indian Railways (IR) is a statutory body under the ownership of Ministry of Railways, Government of India that operates India's national railway system. It manages the fourth largest national railway system in the world by size, with a tota ...

. In the All-India renumbering of 1957, the two class XP locomotives were given the numbers 22599 and 22600, respectively. Both locomotives had been withdrawn from service by 1970.

References

Notes

Bibliography

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External links

* – features a works photo of a class XP locomotive {{Broad gauge locomotives of India , state=collapsed Railway locomotives introduced in 1937 XP Vulcan Foundry locomotives 4-6-2 locomotives 5 ft 6 in gauge locomotives Passenger locomotives Scrapped locomotives