Delaware & Hudson 4-6-2 "Pacific" Locomotives of the USA

Class Details by Steve Llanso of Sweat House Media

Class P (Locobase 3076) published locomotive diagrams that showed the superheat at 840 sq ft, an increase over the original size.

Firebox heating surface includes 40 sq ft (3.7 sq m) of arch tubes.

Because these engines used the big anthracite-burning grate, one can draw a misleading conclusion about this design's ability to steam, particularly in reviewing the A/S ratio of tube/flue cross-section to grate area. Coincidentally, the Railway Age article (14 December 1914) describing these engines makes the point a different way: "According to the method of boiler proportioning used [by Alco], these ...engines have 111 percent boilers." RA explains that 100 percent means ample steam-making capacity, but passenger engines should have some in reserve.

Given the D&H's limited passenger demands these engines were quite worthy and ran until 1952-1953.

Class P-1 (Locobase 143)

Data from 1933 D & H Description of Locomotives books supplied in May 2005 by Allen Stanley from his extensive Raildata collection.

Although laid out according to orthodox American design, these three engines had a British look in their clean boilers, thick and wide face shield below the smokebox, and plain smokebox face with headlight centered. Two had poppet valves and one piston valves -- all were experimental and did not lead to large classes.

Specifications by Steve Llanso of Sweat House Media
Locobase ID3076 143
RailroadDelaware & HudsonDelaware & Hudson
Number in Class103
Road Numbers600-609651-653
Number Built103
Valve GearWalschaertWalschaert
Locomotive Length and Weight
Driver Wheelbase13'13.50'
Engine Wheelbase34.83'35.30'
Ratio of driving wheelbase to overall engine wheebase 0.37 0.38
Overall Wheelbase (engine & tender)70.35'86.56'
Axle Loading (Maximum Weight per Axle)
Weight on Drivers191000 lbs191000 lbs
Engine Weight293500 lbs300000 lbs
Tender Light Weight135000 lbs160500 lbs
Total Engine and Tender Weight428500 lbs460500 lbs
Tender Water Capacity8000 gals11000 gals
Tender Fuel Capacity (oil/coal)14 tons14 tons
Minimum weight of rail (calculated)106 lb/yard106 lb/yard
Geometry Relating to Tractive Effort
Driver Diameter69"73"
Boiler Pressure205 psi260 psi
Cylinders (dia x stroke)24" x 28"22" x 28"
Tractive Effort40729 lbs41027 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.69 4.66
Heating Ability
Firebox Area317 sq. ft320 sq. ft
Grate Area99.32 sq. ft86.94 sq. ft
Evaporative Heating Surface3896 sq. ft3208 sq. ft
Superheating Surface840 sq. ft1495 sq. ft
Combined Heating Surface4736 sq. ft4703 sq. ft
Evaporative Heating Surface/Cylinder Volume265.74260.41
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation2036122604
Same as above plus superheater percentage2402629838
Same as above but substitute firebox area for grate area76682109824
Power L12097046896
Power MT726.141623.89



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