WP
4-6-2
Click to see photo (photo courtesy: Louis T.Cerny)
The WP Class 4-6-2 was the largest class of streamlined locomotive ever built anywhere in the world. Though a favourite locomotive of mine, this webpage will be brief because S.Shankar's WP Glory website is already such a loving tribute to this magnificent engine - a symbol of 1970s India, though it was designed by Baldwin Locomotive Works in the U.S.A., in 1947. Around that time, Baldwin was building streamlined Pacifics for various American railroads. The WPs do have a family resemblance to Baldwin's P7d streamlined 4-6-2s built for the Baltimore and Ohio railroad. Their streamlined shape came from the pen of one Olive Dennis.
The WP had none of the faults of its predecessors, the XB and XC Pacifics. It gave yeoman service to Indian Railways. No wonder it is so loved by Indian railfans.
Luckily for us, Indian Railways has seen fit to preserve a couple of WPs. One of them is at the Rail Museum in New Delhi and the other is in Bombay (to me, it will always be "Bombay". I spent many happy days there as a little boy visiting my grandfather). The one in Bombay is said to be still steamable. Let us pray that its boiler tubes never rust.
TECHNICAL NOTES
Indian Railways' specification for the WP called for a Pacific very similar to the XP Pacific of the Great Indian Peninsula Railway. It was also inspired by the WL 4-6-2, one of which was streamlined to haul the "train of tomorrow" (this WL is not to be confused with the WL light Pacific that was based on the WP). The lessons learned from the XB and XC Pacifics were also incorporated in the design. The first WP prototypes designated WP/P first rode on Indian railway lines in 1947.
The technical features of the WP include: Spring-loaded inter-drawgear; spring controlled engine leading and trailing bogies; high centre of gravity to ensure better riding qualities; Timken roller bearings on all bogies, trucks and eccentric cranks and improved boiler proportions for burning low grade, high ash Indian coal. It also had American features like a very free-steaming boiler, steel firebox, archtubes, self-cleaning smokebox, grate and ashpan, bar frames and cast "Boxpok" wheels. It also incorporated the best of British engineering practices like 7.5 inch valve travel with 1.75 inch valve lap, narrow ring piston valves and leading bogie with "LMS type spring control". Actually, the London Midland and Scottish (LMS) Railway emulated the spring control characteristics first incorporated in the XB Pacifics of India.
Anyone who has studied fluid mechanics will know that a hemispherical smokebox door, i.e., the WP's famous bullet-nose, cannot be the cause of low aerodynamic drag or streamlining! Yet, the bullet-nose remains the most endearing feature of the WP.
DIMENSIONS
Boiler Pressure: 210 psig, Heating Surface: 3082 sq.ft, Grate Area: 46 sq.ft, Cylinders: (2), 20 1/4" Bore x 28" Stroke, Wheel Diameter: 5'-7", Tractive Effort: 30,600 lb, Nominal Axle Load: 18.1 tonnes, Maximum Train Load: 680 tonnes, Drawbar Horsepower = 1500 hp (est.)
