Pennsylvania Other Articulated Locomotives in the USA

Class Details by Steve Llanso of Sweat House Media

Class CC1s (Locobase 12008)

Data from Rob Schoenberg's [] 2 January 2011) and DeGolyer, Volume 40, pp. 268+. Works number was 37674 in April 1912.

This was the earlier prototype Mallet pusher that inspired the Pennsy to buy the ten larger and more powerful CC2s locomotives described in Locobase 1425. Like all Pennsy engines of the time, the CC1s had a Belpaire firebox fed by a Crawford mechanical stoker. The specs show that the firebox heating surface included 32 sq ft (3 sq m) of arch tubes, but the number of tubes seems to have been cut in half once the engine entered service. All four cylinders were served by 14" (356 mm) piston valves.

CC1s served the Lines West (of Pittsburgh) portion of the system as a drag-freighter and pusher.

Class CC2s (Locobase 9498)

Data from "Mallet Articulated Locomotive for Pennsylvania Lines West," Railway and Locomotive Engineering, August 1919, pp. 235. See also DeGolyer, Vol 59, pp. 311+. Baldwin produced them as singles over a 5-month period from April to September 1919 works numbers were 51716, 51867, 51904, 51938, 51973, 51994, 52054, 52227, 52291, 52372). Except for one 3-engine batch, road numbers were typically non-consecutive: 7250, 7332, 7335, 7649, 7693, 9357-9359, 8158, 8183.

These were enormous compound articulateds that were significantly more powerful than the single CC1s experimental engine procured in 1912 (Locobase 12008). Intended for pusher and hump yard service, the CC2s class was designed to work on grades up to 5% and on curves with radii up to 18 deg. So small were the drivers that the leading LP cylinders showed a perceptible rake (1 in 35) to ensure that they'd clear the rail as the front engine traversed in curves. All 4 cylinders were supplied by 14" (356 mm) piston valves. Firebox heating surface area included 76 sq ft (7.05 sq m) in the combustion chamber and 42 sq ft (3.9 sq m) in the arch tubes.

Although deprived of the Belpaire firebox usually found on the Pennsy, the giant switchers nevertheless proved quite satisfactory and remained in service until the late 1940s. The first was sold for scrap in October 1947, the last in April 1949.

Class Pennsylvania (Locobase 2836)

Data from diagram scanned in by Robert Schoenberg of [] . See also "A Webb Compound on the Pennsylvania Railroad," Railway Magazine, Volume 23 (September 1908), pp. 244-245 and "The Efficiency of Compound Locomotives," Engineering News, Volume XXXIII, No. 20 (16 May 1895), pp. 324-326. (Thanks to Chris Hohl for his 4 July 2018 email noting the correct cylinder dimensions.)

One of three non-standard engines the Pennsylvania assessed at the end of the 19th century. This was the London & NorthWestern's Webb Compound. The other two were the 1504, a Schenectady-built simple-expansion (Locobase 2834), and 1510, a Baldwin compound (Locobase 2835).

Choosing the three-cylinder Webb compound system could be questioned on many counts. As Locobases 2173-2174 note about Francis Webb's designs, most locomotive analysts believe the system only persisted on the London & North Western because Webb was difficult to dissuade and he was the boss. Webb strongly believed in his method of compounding and hoped to interest American railroads in its merits. He contracted with Beyer, Peacock to build a single engine.

Very little changed on the engine, which retained the divided drive of their British inspirations. The two HP cylinders drove the crank on the second axle, the single large LP cylinder turned the lead axle. No coupling rods were used.

American practice required the addition of a "cow-catcher" with center coupler and Westinghouse air brake pumps near the rudimentary shelter over the footplate. The copper firebox was fitted with a brick arch.

The experiment was doomed from the start, mostly because of pre-existing and fundamental differences in priorities in engine design between British and American locomotive builders.

American drivers quickly loathed the scanty cab and the Pennsylvania rebuilt the engine with a full housing. But nothing could overcome the 1320's low power and, although the Railway Magazine article ddn't mention it, the use of a single carrying axle forward on a passenger locomotive.

The editor noted the summary judgment passed by T N Ely, then chief of motive power for the Pennsy. The 1320 was well-built and did indeed prove economical, he said.

"[B]ut these proofs of the thoroughness of British workmanship and material did not prevent the engine from reaching the 'scrap heap' at the early date common to American locomotive productions," wrote Railway Magazine's editor. That's a typically severe verdict from a British judge, as the time in service amounted to less than eight years when the 1320 was scrapped in 1897. (Most American locomotives operated for several times as long if the design suited conditions.)

Moreover, the Pennsy's Mr Bishop commented on compounds in the 1895 report from Engineering News. His appraisal of the Webb compound was ungenerous. It was difficult to start because of its divided drive (a problem encountered in British service as well). "The valve motion on that engine, as the men were not able to hear the exhaust, was in very bad shape. Indicator cards showed excessive back pressure in the high-pressure cylinders, and that the valves were not square, so that perhaps would account for not being able to get a speed of much more than 60 miles per hour. The engine was very rough riding, having a very jerky motion."

Principal Dimensions by Steve Llanso of Sweat House Media

Locobase ID12008 9498 2836
RailroadPennsylvania (PRR)Pennsylvania (PRR)Pennsylvania (PRR)
Number in Class1101
Road Numbers33977250+1320
Number Built1101
BuilderBaldwinBaldwinBeyer, Peacock
Valve GearWalschaertWalschaertStephenson
Locomotive Length and Weight
Driver Wheelbase (ft / m)30 / 9.1429.50 / 8.99 9.67 / 2.95
Engine Wheelbase (ft / m)39.50 / 12.0440.12 / 12.2318.09 / 5.51
Ratio of driving wheelbase to overall engine wheelbase 0.76 0.74 0.53
Overall Wheelbase (engine & tender) (ft / m)71.83 / 21.8978.71 / 23.9937.83 / 11.53
Axle Loading (Maximum Weight per Axle) (lbs / kg)54,800 / 24,85734,550 / 15,672
Weight on Drivers (lbs / kg)408,700 / 185,383458,140 / 207,80966,700 / 30,255
Engine Weight (lbs / kg)408,700 / 185,383458,140 / 207,80999,350 / 45,064
Tender Loaded Weight (lbs / kg)186,400 / 84,550191,860 / 87,02657,850 / 26,240
Total Engine and Tender Weight (lbs / kg)595,100 / 269,933650,000 / 294,835157,200 / 71,304
Tender Water Capacity (gals / ML)9000 / 34.0910,000 / 37.882221 / 8.41
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT)17.50 / 1620 / 18 4.50 / 4
Minimum weight of rail (calculated) (lb/yd / kg/m)85 / 42.5095 / 47.5056 / 28
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)56 / 142251 / 129575 / 1905
Boiler Pressure (psi / kPa)205 / 14.10225 / 15.50175 / 12.10
High Pressure Cylinders (dia x stroke) (in / mm)25" x 30" / 635x76226" x 28" / 660x71114" x 24" / 356x610
Low Pressure Cylinders (dia x stroke) (in / mm)39" x 30" / 991x76240" x 28" / 1016x71130" x 24" / 762x610 (1)
Tractive Effort (lbs / kg)82,702 / 37513.0499,796 / 45266.7611,492 / 5212.69
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.94 4.59 5.80
Heating Ability
Tubes (number - dia) (in / mm)259 - 2.25" / 57209 - 2.5" / 64225 - 1.875" / 48
Flues (number - dia) (in / mm)36 - 5.5" / 14052 - 5.5" / 140
Flue/Tube length (ft / m)22.92 / 6.9922 / 6.7111.44 / 3.49
Firebox Area (sq ft / m2)237 / 22.02391 / 36.33193 / 17.93
Grate Area (sq ft / m2)78 / 7.2596.30 / 8.9520.50 / 1.90
Evaporative Heating Surface (sq ft / m2)4921 / 457.345030 / 467.471457 / 135.36
Superheating Surface (sq ft / m2)988 / 91.821406 / 130.67
Combined Heating Surface (sq ft / m2)5909 / 549.166436 / 598.141457 / 135.36
Evaporative Heating Surface/Cylinder Volume288.77292.35341.02
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation15,99021,6683588
Same as above plus superheater percentage18,70826,4343588
Same as above but substitute firebox area for grate area56,844107,33033,775
Power L1691892235397
Power MT298.54355.06356.77

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