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 Wheelbase (ft)1313.50
Engine Wheelbase (ft)34.8335.30
Ratio of driving wheelbase to overall engine wheebase 0.37 0.38
Overall Wheelbase (engine & tender) (ft)70.3586.56
Axle Loading (Maximum Weight per Axle) (lbs)
Weight on Drivers (lbs)191,000191,000
Engine Weight (lbs)293,500300,000
Tender Loaded Weight (lbs)135,000160,500
Total Engine and Tender Weight (lbs)428,500460,500
Tender Water Capacity (gals)800011,000
Tender Fuel Capacity (oil/coal) (gals/tons)1414
Minimum weight of rail (calculated) (lb/yd)106106
Geometry Relating to Tractive Effort
Driver Diameter (in)6973
Boiler Pressure (psi)205260
High Pressure Cylinders (dia x stroke) (in)24" x 28"22" x 28"
Tractive Effort (lbs)40,72941,027
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.69 4.66
Heating Ability
Firebox Area (sq ft)317320
Grate Area (sq ft)99.3286.94
Evaporative Heating Surface (sq ft)38963208
Superheating Surface (sq ft)8401495
Combined Heating Surface (sq ft)47364703
Evaporative Heating Surface/Cylinder Volume265.74260.41
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation20,36122,604
Same as above plus superheater percentage24,02629,838
Same as above but substitute firebox area for grate area76,682109,824
Power L120,97046,896
Power MT726.141623.89



If you have any railroad data such as diagram books, rail station plans or anything else that you would be willing to share, please contact us.