New Haven 4-8-2 "Mountain" Type Locomotives

Class Details by Steve Llanso

Class R-1-b (Locobase 8122)

Data from NH 1962 St Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive collection.

The United States Railroad Administration's Mountain design proved an excellent fit for the New Haven's fast freight requirements, so in addition to the 10 supplied during the USRA's administration, the railroad bought 39 more - 30 in 1920, 9 in 1924. Over time, the class (R-1, R-1-a, R-1-b) was updated with 95 sq ft of syphons and feedwater heaters. Maximum water evaporation rate was calculated at 56,555 lb/hour of which 22,825 lb/hour (40.4%) came from direct heating surfaces. As calculated by the New Haven, maximum steam consumption of 54,580 lb/hour yielded a 104% boiler factor.

To stave off the need to replace the class, the New Haven replaced the class's Southern valve gear with Baker gear in 1940 and fitted them with mechanical lubricators.

Thus equipped, all served the New Haven throughout World War II. Retirements occurred from the end of the war to the end of steam (1946-1951).

Class R-2a (Locobase 216)

This was a quirky mixture of new ideas and auxiliary equipment that in many cases was unsatisfactory. Specified by the New Haven's mechanical manager, WL Bean, the McClellon boiler had a water-tube firebox that leaked and let in cold air. Ultimately all New Haven engines originally delivered with the McClellon boiler had a conventional boiler fitted in 1929. Other problems included a balky DuPont-Simplex mechanical stoker (replaced by an HT-2 in the 1930s) and Southern valve gear replaced by Walschaerts or Baker gear. The design also came equipped with feedwater heater and a valve motion with limited cutoff.

The R-2s ran until 1949-1951.

Class R-3 (Locobase 217)

Boiler had feedwater heater. Unusual 3-cylinder variant of earlier R-2 that also came with the McClellon watertube firebox boiler design. Within a year they'd been reboilered. Note relatively small number of tubes and flues. Although the middle cylinder was a maintenance headache, financial stringency prevented conversion to a two-cylinder layout (as other railroads had done). They ran until 1949-1951.

Specifications by Steve Llanso
Class R-1-b R-2a R-3
Locobase ID 8122 216 217
Railroad New Haven (NYNH&H) New Haven (NYNH&H) New Haven (NYNH&H)
Whyte 4-8-2 4-8-2 4-8-2
Road Numbers 3300-3348 3501-3507 3550-3562
Gauge Std Std Std
Builder Alco-Schenectady Alco Alco-Schenectady
Year 1918 1926 1927
Valve Gear Baker Southern Walschaert
Locomotive Length and Weight
Driver Wheelbase 18.25' 18.25' 19.75'
Engine Wheelbase 40' 40.83' 42.25'
Ratio of driving wheelbase to overall engine wheebase 0.46 0.45 0.47
Overall Wheelbase (engine & tender) 75.62' 83.92' 85.33'
Axle Loading (Maximum Weight per Axle) 58200 lbs 65300 lbs
Weight on Drivers 230500 lbs 246000 lbs 261000 lbs
Engine Weight 334000 lbs 362500 lbs 379000 lbs
Tender Light Weight 184800 lbs 288500 lbs
Total Engine and Tender Weight 518800 lbs 667500 lbs
Tender Water Capacity 16000 gals 16000 gals 16000 gals
Tender Fuel Capacity (oil/coal) 10 tons 18 tons 18 tons
Minimum weight of rail (calculated) on which locomotive could run 96 lb/yard 103 lb/yard 109 lb/yard
Geometry Relating to Tractive Effort
Driver Diameter 69" 69" 69"
Boiler Pressure 200 psi 265 psi 265 psi
Cylinders (dia x stroke) 27" x 30" 27" x 30" 22" x 30" (3)
Tractive Effort 53883 lbs 71394 lbs 71101 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.28 3.45 3.67
Heating Ability
Firebox Area 415 sq. ft 458 sq. ft 451 sq. ft
Grate Area 70.30 sq. ft 70.80 sq. ft 70.80 sq. ft
Evaporative Heating Surface 4188 sq. ft 4135 sq. ft 4085 sq. ft
Superheating Surface 1009 sq. ft 1758 sq. ft 1745 sq. ft
Combined Heating Surface 5197 sq. ft 5893 sq. ft 5830 sq. ft
Evaporative Heating Surface/Cylinder Volume 210.66 207.99 206.33
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation 14060 18762 18762
Same as above plus superheater percentage 16731 24391 24391
Same as above but substitute firebox area for grate area 98770 157781 155370
Power L1 17752 34103 33933
Power MT 679.16 1222.51 1146.50



Introduction and roster provided by Richard Duley . Class details and specifications provided by Steve Llanso of Sweat House Media.