Richmond, Fredericksburg & Potomac / Washington Southern 4-6-2 "Pacific" Locomotives in the USA


Class Details by Steve Llanso of Sweat House Media

Class 151 - superheated (Locobase 7114)

Data from RF&P 1937 locomotive diagram book supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange.

Locobase 7113 shows the original configuration of the first RF & P Pacifics. In the 1920s, a few were substantially made over. Cylinder diameter grew by an inch, 24 flues holding a useful amount of superheater area took the place of 130 tubes and the firebox heating surface grew with the addition of 53 sq ft of thermic syphons.

This class left service over a 17-year period beginning in 1929.


Class 201 - superheated (Locobase 7112)

Data from a RF&P 1937 Locomotive Diagram book supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange.

The first of the many classes of Pacifics used by this passenger bridge road, the 80s (Locobase 5694), now renumbered in the 201 series, were taken in hand and superheated in 1921. The new arrangement included 29 sq ft of arch tubes in the firebox and a tube-flue distribution that retained virtually all of the evaporative heating surface while adding a useful percentage of superheater elements.


Class 264 (Locobase 163)

Data from RF&P 1937 locomotive diagram book supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. Also, see reproduction of 1913 Alco Bulletin 1016 on Richard Leonard's http://www.railarchive.net/alcopacifics/index.html (accessed 16 June 2006). (Many thanks to Chris Hohl for his 22 September 2017 email reporting unlikely boiler pressure values for 177 entries. A Locobase macro caused the error.)

Light Pacific built with superheaters. As delivered, they had 22" (559 mm) diameter cylinders and 190 sq ft (17.65 sq m) of firebox heating surface. Compared to most North American Pacifics then or later, this design had quite a lot of evaporative heating surface for the cylinders it fed.

The later updating shown in the specifications above enlarged the direct heating area by including 29 sq ft (2.69 sq m) of arch tubes and 62 sq ft (5.76 sq m) of thermic syphons in the firebox heating surface. The RF&P also increased cylinder diameter by 1".


Class 301 (Locobase 3310)

This Locobase entry was first recorded as one of the locomotives to which James Partington, Estimating Engineer for Alco, compared his company's #50000 in "Avoidable Waste in Locomotive Operation as Affected by Design", Railway Age, Volume 95, No. 11 (5 November 1921), pp. 673-677. He chose not to identify any of these rivals.

Data from DeGolyer, Vol 74, pp.176+ suggests that this is was the engine to which Partington referred. The class was produced for the RF & P from 1918 to 1925. Alco delivered 301-306 under order R-265 in 1918 and followed with 2 more under order R-293 in 1920. Baldwin's four had works numbers 57587-57588 in December 1923 and 58795-58796 in October 1925.

They were essentially repeats of the earlier 401 (Locobase 1390), but with much taller drivers. Thus, although they resemble the USRA engines in some particulars, this group of locomotives were independently procured. They had 14" (356 mm) piston valves.

As built, the firebox heating surface amounted to 259.6 sq ft, of which 25.6 sq ft was arch tubes. Some time later, the railroad revised the firebox layout; see Locobase 6679.


Class 301 - syphons (Locobase 6679)

Data from RF&P 1937 locomotive diagram book supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange.

About ten years after taking delivery of the last of a dozen high-wheeled passenger Pacifics (Locobase 3310), the RF&P reworked the firebox to gain more heating surface area. Two of the arch tubes were deleted, leaving 16 sq ft (1.5 sq m) and the shops added 75 sq ft (6.95 sq m) of thermic syphons. The locomotives also gained a lot of weight, adding 6 1/2 short tons to the adhesive figure, and almost 12 tons to the engine weight.

The entire class went to the scrappers in 1950 when the RF&P dieselized.


Class 325 (Locobase 164)

Data from tables in 1930 Locomotive Cyclopedia. See also "Two Powerful 4-6-2 Locomotives," Railway Mechanical Engineer, Vol 90, No 1 (January 1916), pp. 4-9 and DeGolyer, Volume 77, pp.534+ . (Many thanks to Chris Hohl for his 22 September 2017 email reporting unlikely boiler pressure values for 177 entries. A Locobase macro caused the error.) Works numbers were 59691-59694 in November 1926.

Other than the Wootten-firebox engines of the anthracite lines, this class had one of the largest grates of all North American Pacifics. RME noted the road's 116 miles (187 km) between Washington and Richmond was the route over which all of the through northern connections of the Seaboard and the Atlantic Coast Lines ran. During the winter, "these trains ...are frequently very heavy, and are hauled at an average speed, including from two to six stops, of 36 to 42 miles per hour [58-67.6 km/h]".

Five arch tubes contributed 34 sq ft (3.15 sq m) to the direct heating surface area. Boiler pressure later raised to 225 psi and TE increased to 52,050 lb (23,610 kg). Fitted with mechanical stokers. Piston valves measuring 14" (356 mm) in diameter supplied steam to the cylinders.

Later (1947) operated by the Chesapeake & Ohio as class F-20 and renumbered 486-489. The first two were scrapped in May 1952, the last two in November 1952.


Class 401 (Locobase 1390)

Data from RF&P 1916 and 1937 Locomotive Diagram books supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. See also DeGolyer, Vol 55, pp. 244+; "Powerful Pacific Type Locomotive for the RF&P", Railway Age Gazette, Volume 59, No. 25 (15 December 1915), pp. 1129-1131; and "Two Powerful 4-6-2 Locomotives," Railway Mechanical Engineer, Vol 90, No 1 (January 1916), pp. 4-9 and Works numbers were 42605-42606 in October 1915 and 43356-43359 in May 1916.

Firebox heating surface area includes 29.2 sq ft (2.7 sq m) in four arch tubes in the firebox heating surface. Baldwin's specs show both the original heating surface estimates and inked corrections; the latter appear in Locobase's specifications.

The July 1916 RME article on the design notes that the Richmond, Fredericksburg & Potomac service on which these engines operated ran at an average of 36-42 mph (58-68 km/h) with six stops pulling very heavy trains.

RME notes the class's 14" (356 mm) "Jack Wilson" balanced slide valves. The first two used Baker valve gear while the last four adopted Southern gear.

This class was updated with several new components in the late 1920s; see Locobase 16029.


Class 401 - syphons (Locobase 16029)

Data from RF&P 1946 Locomotive Diagram books supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange.

Locobase 1390 shows the 401 class as delivered to the RF&P in 1915. When rebuilt in the late 1920s, the class took on a booster, cast trailing trucks and Elesco feedwater heaters. In addition to the 15.2 sq ft (1.4 sq m) of arch tubes delivered with the engines, the shops installed 70 sq ft (6.5 sq m) of thermic syphons. Except in the 403, cylinder diameter grew by 1/2" (12.7 mm). Weight on the drivers grew by 9 1/2 short tons (8,618 kg) and engine operating weight rose by 25,800 lb (11,703 kg). The 15" (381 mm) increase in engine wheelbase resulted from moving the trailing axle further back. This was part of the 18" (457 mm) extension of the length of the firebox and cab behind the last driven axle.

All in all, the update was very similar to the one applied to 301s, whose makeover appears in Locobase 6679.

Ran until 1950.


Class 51/251 (Locobase 1389)

Data from RF&P 1937 locomotive diagram book supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. See also DeGolyer, Volume 43, pp. 21+ and "Pacific Type of Locomotive for the Washington Southern Railway", Railway and Locomotive Engineering, Vol 26, No 5 (May 1913), p. 169. Works numbers were 39110-39114 in January 1913.

Light Pacific built with superheaters. These were delivered to the RF&P's subsidiary Washington Southern at the same time as the Alco-Richmond engines (Locobase 163) but were lighter. Their 14" (356 mm) piston valves supplied steam to the cylinders.

Later, the RF&P revised the power dimensions, reducing cylinder volume by decreasing cylinder diameter to 23 inches (584 mm) while increasing boiler pressure to 200 psi (13.8 bar). They also added 29 sq ft (2.69 sq m) in arch tubes, bringing the direct heating surface total to 225 sq ft (20.9 sq m) and total evaporative heating surface to 3,113 sq ft (289.21 sq m).

The first four were scrapped before US entry into World War Two. Somehow, the 255 remained on the roster until April 1950.


Class 56 / 256 (Locobase 6678)

Data from RF&P 1916 locomotive diagram book supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange.

Built for the Washington Southern at about the same time only a few years after Baldwin built Pacifics for the RF & P (Locobase 5694) , these engines differed primarily in the type of valve gear. They were later superheated along the same lines as the 201 class.


Class 60/151 (Locobase 7113)

Data from RF&P 1916 locomotive diagram book supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange.

These were the first Pacifics on the RF & P; 10 were built by Baldwin for the Washington Southern in 1904, while the other 5, appropriately enough, were supplied to the RF & P by Alco's Richmond works a year later. Virtually identical to the Harriman Light Pacific design then being delivered to the Southern Pacific (Locobase 4407) and Union Pacific (Locobase 4408), the design was relatively small even at that early date.

A few of the class were later superheated; see Locobase 7114.


Class 80 / 201 (Locobase 5694)

Data from June 1908 table in American Engineer and Railroad Journal. Works numbers were 31278-31279, 31349, 31359, 31386, and 31416 in July 1907.

These were delivered with slide valves enjoying a 6" travel. One notable ratio is the relatively small firebox heating surface. As these Pacifics operated for several decades (retirements in a wide span from 1937 to 1950), it's not surprising that they were later superheated. See Locobase 7112.

Specifications by Steve Llanso of Sweat House Media
Class151 - superheated201 - superheated264301301 - syphons
Locobase ID7114 7112 163 3310 6679
RailroadRichmond, Fredericksburg & Potomac (RF&P)Richmond, Fredericksburg & Potomac (RF&P)Richmond, Fredericksburg & Potomac (RF&P)Richmond, Fredericksburg & Potomac (RF&P)Richmond, Fredericksburg & Potomac (RF&P)
CountryUSAUSAUSAUSAUSA
Whyte4-6-24-6-24-6-24-6-24-6-2
Number in Class3651212
Road Numbers151, 153, 15680-85 / 201-20690-94 / 264-268301-31210-21/301-312
GaugeStdStdStdStdStd
Number Built5
BuildershopsRF&PAlco-RichmondRF&Pseveral
Year19261921191319181934
Valve GearWalschaertWalschaertBakerWalschaertWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)12 / 3.6612.83 / 3.9112.83 / 3.9113 / 3.9613 / 3.96
Engine Wheelbase (ft / m)32.50 / 9.9132.67 / 9.9634.67 / 10.5734.92 / 10.6434.92 / 10.64
Ratio of driving wheelbase to overall engine wheebase 0.37 0.39 0.37 0.37 0.37
Overall Wheelbase (engine & tender) (ft / m)65.56 / 19.9864.56 / 19.6867.50 / 20.5773.87 / 22.5273.75 / 22.48
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)142,500 / 64,637156,000 / 70,760161,500 / 73,255194,000 / 87,997207,000 / 93,894
Engine Weight (lbs / kg)210,000 / 95,255249,420 / 113,135244,000 / 110,677287,000 / 130,181310,600 / 140,886
Tender Loaded Weight (lbs / kg)155,500 / 70,534137,900 / 62,550154,200 / 69,944190,000 / 86,183217,600 / 98,702
Total Engine and Tender Weight (lbs / kg)365,500 / 165,789387,320 / 175,685398,200 / 180,621477,000 / 216,364528,200 / 239,588
Tender Water Capacity (gals / ML)7000 / 26.527000 / 26.528000 / 30.3010,000 / 37.8811,000 / 41.67
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)12 / 10.9012 / 10.9016 / 14.5016 / 14.5016 / 14.50
Minimum weight of rail (calculated) (lb/yd / kg/m)79 / 39.5087 / 43.5090 / 45108 / 54115 / 57.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)69 / 175373 / 185473 / 185475 / 190575 / 1905
Boiler Pressure (psi / kPa)200 / 13.80200 / 13.80200 / 13.80200 / 13.80200 / 13.80
High Pressure Cylinders (dia x stroke) (in / mm)21" x 26" / 533x66023" x 28" / 584x71123" x 28" / 584x71126" x 28" / 660x71126" x 28" / 660x711
Tractive Effort (lbs / kg)28,250 / 12814.0034,494 / 15646.2334,494 / 15646.2342,903 / 19460.5042,903 / 19460.50
Factor of Adhesion (Weight on Drivers/Tractive Effort) 5.04 4.52 4.68 4.52 4.82
Heating Ability
Firebox Area (sq ft / m2)226 / 21215 / 19.98273 / 25.37263 / 24.43325 / 30.19
Grate Area (sq ft / m2)49.50 / 4.6049.50 / 4.6049.50 / 4.6066.70 / 6.2066.70 / 6.20
Evaporative Heating Surface (sq ft / m2)2199 / 204.373223 / 299.543159 / 293.594205 / 390.654267 / 396.41
Superheating Surface (sq ft / m2)553 / 51.39812 / 75.46709 / 65.89975 / 90.58975 / 90.58
Combined Heating Surface (sq ft / m2)2752 / 255.764035 / 3753868 / 359.485180 / 481.235242 / 486.99
Evaporative Heating Surface/Cylinder Volume210.98239.37234.62244.39247.99
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation99009900990013,34013,340
Same as above plus superheater percentage11,88011,88011,68215,87515,875
Same as above but substitute firebox area for grate area54,24051,60064,42862,59477,350
Power L118,32920,97519,70820,77021,311
Power MT850.70889.27807.10708.09680.91

Specifications by Steve Llanso of Sweat House Media
Class325401401 - syphons51/25156 / 256
Locobase ID164 1390 16,029 1389 6678
RailroadRichmond, Fredericksburg & Potomac (RF&P)Richmond, Fredericksburg & Potomac (RF&P)Richmond, Fredericksburg & Potomac (RF&P)Washington Southern (RF&P)Richmond, Fredericksburg & Potomac (RF&P)
CountryUSAUSAUSAUSAUSA
Whyte4-6-24-6-24-6-24-6-24-6-2
Number in Class46658
Road Numbers325-3281-6/401-406401-40651-55/251-255256-263
GaugeStdStdStdStdStd
Number Built4658
BuilderBaldwinBaldwinRF&PBaldwinRichmond
Year19271915192919131911
Valve GearWalschaertvariousWalschaertBakerBaker
Locomotive Length and Weight
Driver Wheelbase (ft / m)13 / 3.9613 / 3.9613 / 3.9612.83 / 3.9112.83 / 3.91
Engine Wheelbase (ft / m)35.75 / 10.9034.08 / 10.3935.33 / 10.7732.67 / 9.9634.67 / 10.57
Ratio of driving wheelbase to overall engine wheebase 0.36 0.38 0.37 0.39 0.37
Overall Wheelbase (engine & tender) (ft / m)74.33 / 22.6672.33 / 22.0574.12 / 22.5968.67 / 20.9364.31 / 19.60
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)208,000 / 94,347188,000 / 85,275207,000 / 93,894151,200 / 68,583156,730 / 71,092
Engine Weight (lbs / kg)342,600 / 155,401293,000 / 132,903319,800 / 145,059240,000 / 108,862235,000 / 106,594
Tender Loaded Weight (lbs / kg)210,200 / 95,345179,000 / 81,193184,100 / 83,506130,000 / 58,967138,200 / 62,687
Total Engine and Tender Weight (lbs / kg)552,800 / 250,746472,000 / 214,096503,900 / 228,565370,000 / 167,829373,200 / 169,281
Tender Water Capacity (gals / ML)10,000 / 37.8810,000 / 37.8810,000 / 37.888000 / 30.308000 / 30.30
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)16 / 14.5015 / 13.6015 / 13.6016 / 14.5012 / 10.90
Minimum weight of rail (calculated) (lb/yd / kg/m)116 / 58104 / 52115 / 57.5084 / 4287 / 43.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)75 / 190568 / 172769 / 175373 / 185473 / 1854
Boiler Pressure (psi / kPa)210 / 14.50200 / 13.80200 / 13.80185 / 12.80200 / 13.80
High Pressure Cylinders (dia x stroke) (in / mm)27" x 28" / 686x71126" x 28" / 660x71126.5" x 28" / 673x71124" x 28" / 610x71122" x 28" / 559x711
Tractive Effort (lbs / kg)48,581 / 22036.0047,320 / 21464.0248,445 / 21974.3134,741 / 15758.2731,559 / 14314.94
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.28 3.97 4.27 4.35 4.97
Heating Ability
Firebox Area (sq ft / m2)278 / 25.83248.60 / 23.10317.20 / 29.47196 / 18.21180 / 16.73
Grate Area (sq ft / m2)75.80 / 7.0467 / 6.2266.70 / 6.2049.50 / 4.6049.50 / 4.60
Evaporative Heating Surface (sq ft / m2)4175 / 387.874162 / 386.664259 / 395.673084 / 286.514097 / 380.76
Superheating Surface (sq ft / m2)1078 / 100.15979 / 90.95975 / 90.58709 / 65.87
Combined Heating Surface (sq ft / m2)5253 / 488.025141 / 477.615234 / 486.253793 / 352.384097 / 380.76
Evaporative Heating Surface/Cylinder Volume225.01241.89238.28210.36332.57
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation15,91813,40013,34091589900
Same as above plus superheater percentage19,26115,94615,87510,8979900
Same as above but substitute firebox area for grate area70,64059,16775,49443,14936,000
Power L121,59818,72818,81316,0369870
Power MT686.76658.85601.09701.45416.50

Specifications by Steve Llanso of Sweat House Media
Class60/15180 / 201
Locobase ID7113 5694
RailroadRichmond, Fredericksburg & Potomac (RF&P)Richmond, Fredericksburg & Potomac (RF&P)
CountryUSAUSA
Whyte4-6-24-6-2
Number in Class156
Road Numbers60-74/151-16580-85
GaugeStdStd
Number Built156
BuilderseveralBurnham, Williams & Co
Year19041907
Valve GearBakerWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)12 / 3.6612.83 / 3.91
Engine Wheelbase (ft / m)30.75 / 9.3732.67 / 9.96
Ratio of driving wheelbase to overall engine wheebase 0.39 0.39
Overall Wheelbase (engine & tender) (ft / m)58.45 / 17.8261.96 / 18.89
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)116,620 / 52,898143,750 / 65,204
Engine Weight (lbs / kg)180,560 / 81,901230,800 / 104,689
Tender Loaded Weight (lbs / kg)130,000 / 58,967350,000 / 158,758
Total Engine and Tender Weight (lbs / kg)310,560 / 140,868580,800 / 263,447
Tender Water Capacity (gals / ML)6500 / 24.627000 / 26.52
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)15 / 13.6015 / 13.60
Minimum weight of rail (calculated) (lb/yd / kg/m)65 / 32.5080 / 40
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)68 / 172773 / 1854
Boiler Pressure (psi / kPa)200 / 13.80200 / 13.80
High Pressure Cylinders (dia x stroke) (in / mm)20" x 26" / 508x66022" x 28" / 559x711
Tractive Effort (lbs / kg)26,000 / 11793.4231,559 / 14314.94
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.49 4.55
Heating Ability
Firebox Area (sq ft / m2)176.70 / 16.42190 / 17.66
Grate Area (sq ft / m2)49.50 / 4.6049.50 / 4.60
Evaporative Heating Surface (sq ft / m2)2967 / 275.744107 / 381.69
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)2967 / 275.744107 / 381.69
Evaporative Heating Surface/Cylinder Volume313.84333.38
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation99009900
Same as above plus superheater percentage99009900
Same as above but substitute firebox area for grate area35,34038,000
Power L192329989
Power MT523.57459.59

Reference