New Haven 4-8-2 "Mountain" Locomotives in the USA

Class Details by Steve Llanso of Sweat House Media

Class R-1-a (Locobase 15995)

Data from "Mountain Type Locomotives for the New Haven", Railway Mechanical Engineer, Volume 94, No 11 (November 1920), pp.685-688 . Works numbers were 59790-59799 in August 1919 from Richmond, 62205--62234 in August-September 1920 from Schenectady.

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 ten supplied during the USRA's administration, the railroad bought 30 more in 1920. The boiler was little changed, although superheater area increased by 53 sq ft. The five-foot long combustion chamber added 106 sq ft (9.85 sq m).

These engines were among the first to be built with feed water heaters installed. They were type E-1s from Locomotive Feedwater Heater Company; the pump could move 7,500 gallons (28,388 litres) per hour.

Class R-1-b - syphons and FWH (Locobase 8122)

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

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 (Locobase 15995) and 9 in 1924. Over time, the class (R-1, R-1-a, R-1-b) was updated with 95 sq ft of syphons.

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-2 (Locobase 16073)

Data from NH 1962 Steam Locomotives supplied in August 2013 by Allen Stanley from his extensive Rail Data Exchange. See also "McClellon Watertube Type Locomotive Boiler,", The Boiler Maker (March 1926), pp. 65-70, 82. (Many thanks to Chris Hohl for his 4 April 2015 email noting the absence of the 3500 and supplying information and data on this locomotive.) Works number was 64946 in December 1924.

Although the specifications describe this locomotive after it was rebuilt as a conventional locomotive in 1929, it entered service as a test vehicle for a revised design of the McClellon watertube boiler. The Boiler Maker report says that the first two boilers built to this design were mounted on 2-8-2s in 1916, but "met with indifferent success." Troublesome weaknesses could be corrected and the design was "fundamentally sound", but McClellon died soon thereafter and it was only in 1920 that the New Haven's mechanical manager W L Bean could make the changes to the original boilers.

Bean doubled-down on this considerable variation of the conventional firebox by asking Schenectady to modify the 49th R-1 to a revised design. Numbered 3500 and designated R-2, the new locomotive appeared in 1924. Locobase recommends that those interested in all the details consult the long article cited above.

Here are the basic elements of the design, however. In place of side and back sheets in the firebox and side sheets in the combustion chamber, a picket line of vertical watertubes carried around all three sides. A photo shows that the backhead was framed in channel beams to provide a template for a heavy plate cross member that was bolted on pads on the two side channel beams. Two tubes on either side of the firedoor structure were significantly bowed--e.g. ()-- at the level of the firedoor. 43 tubes in the side sheets and 15 more in the combustion chamber had 4" diameters swaged to 3" at the ends; the back head tubes had constant 2" diameters.

As with other watertube boiler designs, the tubes conveyed water from the foundation ring at the bottom of the firebox to drums above the firebox proper. In the McClellon design, two 23" (584 mm) drums flanked the 30"' center drum as the three ran longitudinally from back head to the front sheet of the combustion chamber. The drums were open at the front.

Despite all the assurances that the problems with leaks in a watertube firebox had been addressed, the system proved leaky enough. Bean had already ordered seven more R-1a, which differed from the 3500 in having Type E superheaters; see Locobase 216. Three more were ordered as three-cylinder engines; see Locobase 217.

Like the others, the 3500's watertube firebox was replace in 1929 by a conventional furnace. In addition to the firebox itself, the direct heating surface area included 101 sq ft (9.4 sq m) in the combustion chamber and 95 sq ft (8.8 sq m) of thermic syphons in the firebox and combustion chamber. Feed water was heated through an Elesco installation. Steam entered the cylinders through 14" (356 mm) piston valves actuated by Baker gear, which replaced the original Southern gear installation.

Class R-2a (Locobase 216)

Data from tables in 1930 Locomotive Cyclopedia and NH 1962 Steam Locomotives supplied in August 2013 by Allen Stanley from his extensive Rail Data Exchange. Works numbers were 64945-64946 in 1924; 66545-66551 in June-July 1926.

This was a quirky mixture of new ideas such as the Type E superheater 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. See Locobase 16073 for a longer description of this design.

Ultimately all New Haven engines originally delivered with the McClellon boiler had a conventional boiler fitted in 1929. The specs refer to the later boiler, whose firebox heating surface area included 101 sq ft (9.38 sq m) in the combustion chamber and 95 sq ft (8.83 sq m) of thermic syphons. 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. 14" (356 mm) piston valves supplied steam to the cylinders.

The R-2s ran until 1949-1951.

Class R-3 (Locobase 217)

Data from tables in 1930 Locomotive Cyclopedia and NH 1962 Steam Locomotives supplied in August 2013 by Allen Stanley from his extensive Rail Data Exchange. See also "mp15ac" in a 27 March 2006 post to the Trains forum at, last accessed 8 May 2016 and Richard Marsden's summary at his LNER Encyclopedia,, also last accessed 8 May 2016.. (Thanks to Chris Hohl for his comments on the Gresley system as used in the Alco three-cylinder engines.) Works numbers were 66552-66554 in 1926, 67227-67236 in January 1928.

Boiler had feedwater heater. Unusual three-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).

"Stuart" -- "mp15ac" -- summarized the positive values of the Gresley conjugated gear: "Alco used the Gresley three cylinder valve gear system on all of the three cylinder locomotives that they built. The beauty of the Gresley system is that with the exception of the mainrod for the center cylinder all other parts were outside of the frames. This made servicing easier than the double Walschaets system used by Baldwin. "

In a dialogue about the R-3s in , "Paul3" from Massachusetts, in a 23 May 2006 post, quoted Jack Swanberg's book New Haven Power as part of a dissent from the contention that the third cylinder's maintenance demands rendered them unpopular. From Swanberg, pp. 184-185: "The operating dept. loved the R-3's. From "New Haven Power", by Jack Swanberg, page 184-185. "Listen to retired General Road Foreman Bill Copeland as he lights up when he thinks of his many years on these locomotives: 'The three cylinder engines had a terrific draft; the sound was chickety-chick, chickety-chick; one strong and two light ...They could run like a scared cat, and pull an awful train at high speed. They could take 5000 tons up the Shore Line while an R-2a might take 3500 tons at best ...and coming west out of Boston with 125 empties, how they would come!'"

They ran until 1949-1951.

Principal Dimensions by Steve Llanso of Sweat House Media
ClassR-1-aR-1-b - syphons and FWHR-2R-2aR-3
Locobase ID15,995 8122 16,073 216 217
RailroadNew Haven (NYNH&H)New Haven (NYNH&H)New Haven (NYNH&H)New Haven (NYNH&H)New Haven (NYNH&H)
Number in Class49491713
Road Numbers3300-33483300-334835003501-35073550-3562
Number Built49491713
Valve GearSouthernBakerBakerBakerWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)18.25 / 5.5618.25 / 5.5618.25 / 5.5618.25 / 5.5619.75 / 6.02
Engine Wheelbase (ft / m)40 / 12.1940 / 12.1940.83 / 12.4440.83 / 12.4442.25 / 12.88
Ratio of driving wheelbase to overall engine wheebase 0.46 0.46 0.45 0.45 0.47
Overall Wheelbase (engine & tender) (ft / m)75.62 / 23.0575.62 / 23.0583.67 / 25.5083.92 / 25.5885.33 / 26.01
Axle Loading (Maximum Weight per Axle) (lbs / kg)58,200 / 26,39958,200 / 26,35461,300 / 27,80561,700 / 27,98765,300 / 29,620
Weight on Drivers (lbs / kg)229,000 / 103,873230,500 / 104,553244,500 / 110,903246,500 / 111,811261,000 / 118,388
Engine Weight (lbs / kg)328,500 / 149,005334,000 / 151,500360,700 / 163,611363,200 / 164,745379,000 / 171,912
Tender Loaded Weight (lbs / kg)182,500 / 82,781184,800 / 83,824286,000 / 129,728288,500 / 130,862288,500 / 130,862
Total Engine and Tender Weight (lbs / kg)511,000 / 231,786518,800 / 235,324646,700 / 293,339651,700 / 295,607667,500 / 302,774
Tender Water Capacity (gals / ML)10,000 / 37.8816,000 / 60.6116,000 / 60.6116,000 / 60.6116,000 / 60.61
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)16 / 14.5010 / 9.1018 / 16.4018 / 16.4018 / 16.40
Minimum weight of rail (calculated) (lb/yd / kg/m)95 / 47.5096 / 48102 / 51103 / 51.50109 / 54.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)69 / 175369 / 175369 / 175369 / 175369 / 1753
Boiler Pressure (psi / kPa)200 / 13.80200 / 13.80250 / 17.20265 / 18.30265 / 18.30
High Pressure Cylinders (dia x stroke) (in / mm)27" x 30" / 686x76227" x 30" / 686x76227" x 30" / 686x76225" x 30" / 635x76222" x 30" / 559x762 (3)
Tractive Effort (lbs / kg)53,883 / 24440.9553,883 / 24440.9567,353 / 30550.8461,209 / 27763.9771,101 / 32250.91
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.25 4.28 3.63 4.03 3.67
Heating Ability
Firebox Area (sq ft / m2)348 / 32.33415 / 38.57421 / 39.11421 / 39.11451 / 41.91
Grate Area (sq ft / m2)70.30 / 6.5370.30 / 6.5370.20 / 6.5270.20 / 6.5270.80 / 6.58
Evaporative Heating Surface (sq ft / m2)4121 / 382.854188 / 389.224011 / 372.633989 / 370.594085 / 379.65
Superheating Surface (sq ft / m2)1009 / 93.741009 / 93.771009 / 93.741818 / 168.901745 / 162.17
Combined Heating Surface (sq ft / m2)5130 / 476.595197 / 482.995020 / 466.375807 / 539.495830 / 541.82
Evaporative Heating Surface/Cylinder Volume207.29210.66201.76234.04206.33
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation14,06014,06017,55018,60318,762
Same as above plus superheater percentage16,87216,73121,06024,37024,391
Same as above but substitute firebox area for grate area83,52098,770126,300146,150155,370
Power L117,28717,75221,97740,15133,933
Power MT665.70679.16792.651436.391146.50