Washington Southern / Richmond, Fredericksburg & Potomac 4-6-2 "Pacific" Type Locomotives

Class Details by Steve Llanso

Class 151 - superheated (Locobase 7114)

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

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 collection.

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 collection. Also, see reproduction of 1913 Alco Bulletin 1016 on Richard Leonard's http://www.railarchive.net/alcopacifics/index.html (accessed 16 June 2006).

Light Pacific built with superheaters. As delivered, they had 22"-diameter cylinders and 190 sq ft 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.

A later updating enlarged the direct heating area by including 29 sq ft of arch tubes and 62 sq ft 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 (Locobase 6679)

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

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, Vol 77, pp.534+ . 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 collection. See also DeGolyer, Vol 55, pp. 244+ and "Two Powerful 4-6-2 Locomotives," Railway Mechanical Engineer, Vol 90, No 1 (January 1916), pp. 4-9. 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 Railway Mechanical Engineer (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.

When this class was later updated, the firebox heating surface increased to 316.2 sq ft (29.4 sq m), to which arch tubes contributed 15.2 sq ft (1.4 sq m) and thermic syphons 70 sq ft (6.5 sq m).

Passenger Pacifics later rebuilt with cast trailing trucks and Elesco feedwater heaters. 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 collection. See also DeGolyer, Vol 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) and driver diameter by four inches to 69" (1,753 mm) while increasing boiler pressure to 200 psi (13.8 bar). They also added 31 sq ft (2.9 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 3,125 sq ft (290.3 sq m).

The first four were scrapped before US entry into World War Two. Somehow, the 55 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 collection.

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 collection.

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
Class151 - superheated201 - superheated26430130132540151 /25156 / 25660 / 15180 / 201
Locobase ID7114 7112 163 3310 6679 164 1390 1389 6678 7113 5694
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)Richmond, Fredericksburg & Potomac (RF&P)Richmond, Fredericksburg & Potomac (RF&P)Washington Southern (RF&P)Richmond, Fredericksburg & Potomac (RF&P)Richmond, Fredericksburg & Potomac (RF&P)Richmond, Fredericksburg & Potomac (RF&P)
Road Numbers151, 153, 15680-85 / 201-20690-94 / 264-268301-31210-21 / 301-312325-3281-6 / 401-40651-55 / 251-255256-26360-74 / 151-16580-85
BuildershopsRF&PAlco-RichmondRF&PseveralBaldwinBaldwinBaldwinRichmondseveralBurnham, Williams & Co
Valve GearWalschaertWalschaertBakerWalschaertWalschaertWalschaertvariousBakerBakerBakerWalschaert
Locomotive Length and Weight
Driver Wheelbase12'12.83'12.83'13'13'13'13'12.83'12.83'12'12.83'
Engine Wheelbase32.50'32.67'34.67'34.92'34.92'35.75'34.08'32.67'34.67'30.75'32.67'
Ratio of driving wheelbase to overall engine wheebase 0.37 0.39 0.37 0.37 0.37 0.36 0.38 0.39 0.37 0.39 0.39
Overall Wheelbase (engine & tender)65.56'64.56'67.50'73.87'73.75'74.33'72.33'68.67'64.31'58.45'61.96'
Axle Loading (Maximum Weight per Axle)
Weight on Drivers142500 lbs156000 lbs161500 lbs194000 lbs207000 lbs208000 lbs188000 lbs151200 lbs156730 lbs116620 lbs143750 lbs
Engine Weight210000 lbs249420 lbs244000 lbs287000 lbs310600 lbs342600 lbs293000 lbs240000 lbs235000 lbs180560 lbs230800 lbs
Tender Light Weight155500 lbs137900 lbs154200 lbs190000 lbs217600 lbs210200 lbs179000 lbs130000 lbs138200 lbs130000 lbs350000 lbs
Total Engine and Tender Weight365500 lbs387320 lbs398200 lbs477000 lbs528200 lbs552800 lbs472000 lbs370000 lbs373200 lbs310560 lbs580800 lbs
Tender Water Capacity7000 gals7000 gals8000 gals10000 gals11000 gals10000 gals10000 gals8000 gals8000 gals6500 gals7000 gals
Tender Fuel Capacity (oil/coal)12 tons12 tons16 tons16 tons16 tons16 tons15 tons16 tons12 tons15 tons15 tons
Minimum weight of rail (calculated) on which locomotive could run79 lb/yard87 lb/yard90 lb/yard108 lb/yard115 lb/yard116 lb/yard104 lb/yard84 lb/yard87 lb/yard65 lb/yard80 lb/yard
Geometry Relating to Tractive Effort
Driver Diameter69"73"73"75"75"75"68"73"73"68"73"
Boiler Pressure200 psi200 psi200 psi200 psi200 psi210 psi200 psi185 psi200 psi200 psi200 psi
Cylinders (dia x stroke)21" x 26"23" x 28"23" x 28"26" x 28"26" x 28"27" x 28"26" x 28"24" x 28"22" x 28"20" x 26"22" x 28"
Tractive Effort28250 lbs34494 lbs34494 lbs42903 lbs42903 lbs48581 lbs47320 lbs34741 lbs31559 lbs26000 lbs31559 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 5.04 4.52 4.68 4.52 4.82 4.28 3.97 4.35 4.97 4.49 4.55
Heating Ability
Firebox Area226 sq. ft215 sq. ft273 sq. ft263 sq. ft325 sq. ft278 sq. ft248.60 sq. ft196 sq. ft180 sq. ft176.70 sq. ft190 sq. ft
Grate Area49.50 sq. ft49.50 sq. ft49.50 sq. ft66.70 sq. ft66.70 sq. ft75.80 sq. ft67 sq. ft49.50 sq. ft49.50 sq. ft49.50 sq. ft49.50 sq. ft
Evaporative Heating Surface2199 sq. ft3223 sq. ft3159 sq. ft4205 sq. ft4267 sq. ft4175 sq. ft4162 sq. ft3084 sq. ft4097 sq. ft2967 sq. ft4107 sq. ft
Superheating Surface553 sq. ft812 sq. ft709 sq. ft975 sq. ft975 sq. ft1078 sq. ft979 sq. ft709 sq. ft
Combined Heating Surface2752 sq. ft4035 sq. ft3868 sq. ft5180 sq. ft5242 sq. ft5253 sq. ft5141 sq. ft3793 sq. ft4097 sq. ft2967 sq. ft4107 sq. ft
Evaporative Heating Surface/Cylinder Volume210.98239.37234.62244.39247.99225.01241.89210.36332.57313.84333.38
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation990099009900133401334015918134009158990099009900
Same as above plus superheater percentage1188011880116821587515875192611594610897990099009900
Same as above but substitute firebox area for grate area5424051600644286259477350706405916743149360003534038000
Power L11832920975197082077021311215981872816036987092329989
Power MT850.70889.27807.10708.09680.91686.76658.85701.45416.50523.57459.59



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