Great Indian Peninsula 4-6-2 Locomotives in India

Class Details by Steve Llanso of Sweat House Media

Class XP (Locobase 20931)

Data from No. 65, "'XP'' Class Fitted with 'Caprotti' Valve Gear Standard Passenger Engine and Tender for the Indian State Railways", Vulcan Foundry Locomotive Catalogue found on Flicker's Historical Locomotive Images website at [], last accessed 26 June 2021. See also "XP" on the Indian Railways Fan Club Association (IRFCA) website at [], last accessed 10 August 2021. (Many thanks to Jorge Cerezo Toledo for his 26 June 2021 email containing links to several sites including the Vulcan Catalogue referred to above.) Works numbers were 4694-4695

This pair of powerful ISR Pacific used the straight boiler and firebox as XB Heavy Pacifics (Locobase 2589), but featured several modern appliances that included an ACFI feed water heater, two Nicholson thermic syphons, roller bearing axleboxes on all engine and tender axles (Timken on 3100, Skefco on 3101), and Caprotti valve gear.

IRFCA comments that the XPs were experimental, as the extras loaded onto the basic XB design suggest, "with the aim of gaining the power of the XC within the operating area of the XB. The aim was to achieve running mileages of 200,000 miles [322,000 km] between overhauls, and a monthly average of 10,000 miles. These were very high figures for the time."

Of greater importance is IRFCA's note that the XPs "were the basis for "India's renowned WP class 4-6-2 [Locobase 2480].

Principal Dimensions by Steve Llanso of Middle Run Media

Locobase ID20931
RailroadGreat Indian Peninsula
Number in Class2
Road Numbers3100-3101/22599-22600
Number Built2
BuilderVulcan Foundry
Valve GearCaprotti
Locomotive Length and Weight
Driver Wheelbase (ft / m)13.17 / 4.01
Engine Wheelbase (ft / m)36.83 / 11.23
Ratio of driving wheelbase to overall engine wheelbase 0.36
Overall Wheelbase (engine & tender) (ft / m)67.37 / 20.53
Axle Loading (Maximum Weight per Axle) (lbs / kg)42,000 / 19,051
Weight on Drivers (lbs / kg)124,880 / 56,645
Engine Weight (lbs / kg)221,760 / 100,589
Tender Loaded Weight (lbs / kg)165,760 / 75,188
Total Engine and Tender Weight (lbs / kg)387,520 / 175,777
Tender Water Capacity (gals / ML)6050 / 22.92
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT)14.30 / 13
Minimum weight of rail (calculated) (lb/yd / kg/m)69 / 34.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)74 / 1880
Boiler Pressure (psi / kPa)210 / 14.50
High Pressure Cylinders (dia x stroke) (in / mm)21.5" x 28" / 546x711
Tractive Effort (lbs / kg)31,221 / 14161.62
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.00
Heating Ability
Tubes (number - dia) (in / mm)83 - 2.25" / 57
Flues (number - dia) (in / mm)24 - 5.5" / 140
Flue/Tube length (ft / m)18.53 / 5.65
Firebox Area (sq ft / m2)242 / 22.48
Grate Area (sq ft / m2)45 / 4.18
Evaporative Heating Surface (sq ft / m2)1785 / 165.83
Superheating Surface (sq ft / m2)504 / 46.82
Combined Heating Surface (sq ft / m2)2289 / 212.65
Evaporative Heating Surface/Cylinder Volume151.71
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation9450
Same as above plus superheater percentage11,529
Same as above but substitute firebox area for grate area62,000
Power L116,578
Power MT878.00

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