Philadelphia & Reading 2-8-8-0 "Consolidation Mallet" Locomotives in the USA

Class Details by Steve Llanso of Sweat House Media

Class N1-sd (Locobase 16269)

Data from RDG 11 - 1926 Locomotive Diagram book and various editions of the Reading Equipment Lists supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. (Thanks to Nate Kelly for his 2 March 2017 email highlighting the differences in the N1-sd, which led to a revision of the version identification in the original Locobase 326 entry.)

Thirty-one Mallet articulateds were delivered to the Reading from 1917 to 1919; they're shown in Locobase 326.

The class was broken up in the late 1920s when the first eleven engines were converted to K1-sa and K1-sc Santa Fe-type 2-10-2s; see Locobase 83. The remaining compounds were redesignated N1-sb (1816-1830) if they had Standard stokers and N1-sc (1811-1815) if they used the Street Duplex stoker.

All of the twenty remaining engines were eventually rebuilt as N1-sd simple-expansion articulateds. They had Wootten fireboxes and Hulson grates. Their firebox heating surface areas included 98 sq ft (9.1 sq m) in three thermic syphons. They were fitted with Ragonnet 9" Type A power reverse gear. The first four engines to be rebuilt --1811, 1816, 1818, and 1821-- were converted by 1936 with the rest completed by 1945.

All of the N1-sd locomotives lost a trailing truck between 1940 and 1944 and operated as 2-8-8-0s. Adhesion weight rose to 477,846 lb (216,748 kg) and engine weight dropped to 495,180 lb (224,610 kg).

Principal Dimensions by Steve Llanso of Sweat House Media
Locobase ID16,269
RailroadPhiladelphia & Reading
Number in Class31
Road Numbers1811-1830
Number Built31
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)16 / 4.88
Engine Wheelbase (ft / m)55.83 / 17.02
Ratio of driving wheelbase to overall engine wheebase 0.29
Overall Wheelbase (engine & tender) (ft / m)82.98 / 25.29
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)447,500 / 202,983
Engine Weight (lbs / kg)496,300 / 225,118
Tender Loaded Weight (lbs / kg)
Total Engine and Tender Weight (lbs / kg)496,300
Tender Water Capacity (gals / ML)11,000 / 41.67
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)10 / 9.10
Minimum weight of rail (calculated) (lb/yd / kg/m)93 / 46.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)55.50 / 1410
Boiler Pressure (psi / kPa)225 / 15.50
High Pressure Cylinders (dia x stroke) (in / mm)23" x 32" / 584x813 (4)
Tractive Effort (lbs / kg)116,666 / 52918.87
Factor of Adhesion (Weight on Drivers/Tractive Effort) 3.84
Heating Ability
Firebox Area (sq ft / m2)452 / 41.99
Grate Area (sq ft / m2)108 / 10.03
Evaporative Heating Surface (sq ft / m2)5841 / 542.64
Superheating Surface (sq ft / m2)1450 / 134.71
Combined Heating Surface (sq ft / m2)7291 / 677.35
Evaporative Heating Surface/Cylinder Volume189.79
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation24,300
Same as above plus superheater percentage29,160
Same as above but substitute firebox area for grate area122,040
Power L114,304
Power MT563.75

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Wes Barris