Pittsburgh & West Virginia 2-6-6-4 Locomotives in the USA

Class Details by Steve Llanso of Sweat House Media

Class J-1/J-2 (Locobase 301)

Data from 1930 Locomotive Cyclopedia, supplemented by P&WV 12-1937 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. See also William Withuhn, American Steam Locomotives: Design and Development: 1880-1960 (Bloomington, IN: Indiana University Press and Pflugerville, TX: Railway & Locomotive Historical Society, 2019), p. 301-302. .(Thanks to Chris Hohl, whose 14 October 2019 email noted the difference in tender weight of those fitted with tender boosters and those tenders without the booster and a commensurate increase in driver diameter.) After) Works numbers ran 61788-61790 in 1934, 61950-61951 in 1936, and 62016-62017 in September 1937.

EW King, Jr. (in Drury, 1993) on the 2-6-6-4 design, of which these P&WVs were the first examples: "These locomotives were designed back to front. First consideration was given to providing a firebox-boiler combination capable of the required horsepower output -- a deep Belpaire firebox of liberal grate area located entirely behind the driving wheels." The low driver diameter (initially 63"/1,600 mm) didn't bother the P&WV because as a coal road, it didn't dabble in high speeds anyway.

William Withuhn commented that Baldwin had to persuade the P&WV that it wouldn't duplicate the B&O experience with some 2-6-6-2s supplied a few years earlier. How could they be sure, he wondered? Beginning "in the years after 1930", Baldwin went to school on Alco's development of a front engine setup based on a hinge, the "essential ingredient" of which was "tightening up the hinge and preventing pitch change in the front unit."

The change in behavior was dramatic: the J-1s and later J-2s "ran beautifully, with excellent traction." Withuhn adds that Alfred Bruce, "ever loyal to articulation pioneer Alco", claimed that the Baldwins' front engine unit was "inclined to 'hunt' at high speed. But he conceded that "speeds of 50 to 60 miles per hour" had been reported.

J-1s had a tender-mounted side-rod booster engine generated 16,000 lb (7,257 kg or 71.17 kN) that proved to be a maintenance headache (an extra 30"/762 mm between the first and second axles of the rear truck bore witness to the booster even after it was removed). Chris Hohl pointed out that after the tender boosters were removed, the railroad increased their driver diameters to 64" (1,626 mm).

Chris Hohl pointed out that when the railroad removed the tender booster, tender empty weight dropped from 171,000 lb (77,111 kg) to 148,485 lb 67,352 kg) and the loaded weight of 387,600 lb shown in the specs to 365,086 lb (165,600 kg).

J-2s didn't have the booster. Firebox heating surface included 150 sq ft (13.94 sq m) from the combustion chamber and 49 sq ft (4.55 sq m) of five "firebrick" tubes. Piston valves measured 12" (305 mm) in diameter.

Principal Dimensions by Steve Llanso of Sweat House Media

Locobase ID301
RailroadPittsburgh & West Virginia
Number in Class7
Road Numbers1100-1106
Number Built7
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)22 / 6.71
Engine Wheelbase (ft / m)55.66 / 16.97
Ratio of driving wheelbase to overall engine wheelbase 0.40
Overall Wheelbase (engine & tender) (ft / m)98.33 / 29.97
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)397,300 / 180,212
Engine Weight (lbs / kg)528,040 / 239,515
Tender Loaded Weight (lbs / kg)387,600 / 175,813
Total Engine and Tender Weight (lbs / kg)915,640 / 415,328
Tender Water Capacity (gals / ML)20,000 / 75.76
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT)25 / 23
Minimum weight of rail (calculated) (lb/yd / kg/m)110 / 55
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)64 / 1626
Boiler Pressure (psi / kPa)225 / 15.50
High Pressure Cylinders (dia x stroke) (in / mm)23" x 32" / 584x813 (4)
Tractive Effort (lbs / kg)101,171 / 45890.45
Booster (lbs)16,000
Factor of Adhesion (Weight on Drivers/Tractive Effort) 3.93
Heating Ability
Tubes (number - dia) (in / mm)241 - 2.25" / 57
Flues (number - dia) (in / mm)66 - 5.5" / 140
Flue/Tube length (ft / m)23 / 7.01
Firebox Area (sq ft / m2)499 / 46.36
Grate Area (sq ft / m2)102.30 / 9.51
Evaporative Heating Surface (sq ft / m2)5914 / 549.63
Superheating Surface (sq ft / m2)1873 / 174.07
Combined Heating Surface (sq ft / m2)7787 / 723.70
Evaporative Heating Surface/Cylinder Volume192.14
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation23,018
Same as above plus superheater percentage28,542
Same as above but substitute firebox area for grate area139,221
Power L119,701
Power MT655.93

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