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 | |
|---|---|
| Class | XP |
| Locobase ID | 20931 |
| Railroad | Great Indian Peninsula |
| Country | India |
| Whyte | 4-6-2 |
| Number in Class | 2 |
| Road Numbers | 3100-3101/22599-22600 |
| Gauge | 5'6" |
| Number Built | 2 |
| Builder | Vulcan Foundry |
| Year | 1935 |
| Valve Gear | Caprotti |
| 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 / 1450 |
| 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 Volume | 151.71 |
| Computations Relating to Power Output (More Information) | |
| Robert LeMassena's Power Computation | 9450 |
| Same as above plus superheater percentage | 11,529 |
| Same as above but substitute firebox area for grate area | 62,000 |
| Power L1 | 16,578 |
| Power MT | 878.00 |