Baltimore & Ohio / Buffalo, Rochester, & Pittsburgh / Cincinnati, Hamilton & Dayton / Cincinnati, Indianapolis, & Western 4-6-2 "Pacific" Locomotives of the USA

Baltimore & Ohio

The Baltimore & Ohio was one of the "Trunk Lines" mentioned earlier. (The term "Trunk Lines" originated in a rate-setting agreement between the Pennsylvania, New York Central, Baltimore & Ohio and the Erie in the 1880s.) The B&O extended from Philadelphia, though Baltimore and Washington DC to Chicago and St. Louis. It covered a wide variety of country; the flat raceways of Illinois and Indiana, the highly competitive East Coast run between DC and the Hudson (via Reading and Central New Jersey trackage rights in the case of the B&O). It also included considerable heavy grade territory; the main line split at Cumberland, MD; the Chicago line went to the northwest via heavy grades to Pittsburgh; the line to Cincinnati and St. Louis went almost due west over exceptionally heavy grades. Another characteristic of the B&O was that it had certain districts where the tracks could not accommodate its heaviest power, unlike the New York Central and Pennsylvania where practically all classes could operate over practically every mile of track owned. In particular, the line to Cincinnati and St. Louis running through Ohio, Indiana and Illinois could not handle the heaviest B&O motive power.

The B&O had another distinction; it was, in the decades between the Wars, one of the most experimental roads in the United States in motive power matters. Also, next to the Illinois Central, it was the great rebuilder of steam locomotives. Yet, from the first 4-6-2 in 1906 until complete dieselization in the 1950s, Pacifics were the locomotives which hauled the passenger trains. 1

The first Pacifics owned by the B&O were built in 1906 by Alco (Schenectady), not in general much of a B&O supplier. They were built as saturated locomotives with Stephenson valve gear; by 1926, when most had become superheated, and most had had their valve gear changed to Walschaerts, they had been renumbered into the 5150-5184 series, and classified as P, Pa, Pb and Pc. All had 74 inch drivers, and 24 or 26 x 32 cylinders, steam pressures varying between 190 and 205 psi. Tractive efforts were on the order of 30,700 to 34,300 lbs, depending upon which particular combination of cylinder size and boiler pressure each locomotive had, and weights (without tender, in all examples) ranged between 229,500 and 242,800 lbs.

These locomotives were all scrapped by 1949. At the time they were built, the B&O was still relying upon Atlantics and Ten Wheelers to haul the Washington - Philadelphia trains as late as 1913; indeed, the road ordered its last Atlantics as late as 1910, superheated. The P class generally was employed West of Baltimore, primarily on Chicago bound trains. The next Pacifics came from Baldwin in 1911, 30 class P1a, 5060-5089, and 10 class P1aa, 5050-5059. P1a had 74 inch drivers, 24 x 32 cylinders and 205 psi boiler pressure, 43,900 lbs te. P1aa had 26 x 32 cylinders, 190 psi and 47,200 lbs te. Both classes weighed 277,200 lbs. These locomotives were "heavy" Pacifics by any standard. They were used west of Baltimore, in particular over the grades west of Cumberland. One presumes that this released the 1911 Pacifics for work on low-grade lines.

The B&O was an inveterate rebuilder. Starting about 1924 with a class called P1c, they rebuilt a group of Mikados into heavy Pacifics. There were about 30, numbered more or less at random between 5000 and 5094. The specifications were 74-inch drivers, 26 1/2 x 28 inch cylinders (a very odd proportion) and 215 psi. Tractive force was 44,600 lbs, and weight was 299,000. From that point, the B&O went further; not only did it rebuild the P1d rebuilds, but also it took some of the Baldwin P1s and rebuild them. The difference was that the working pressure was 225 psi, the starting tractive effort 51,000lbs and the weight 317,000 pounds. There were 29 by 1938, and three more were added by 1942. (Obviously, not of all the earlier P1 sub classes were converted.) These locomotives, which lasted until 1957, were the mountain haulers, both as road engines and helpers of B&O passenger service.

The next class was the P3/4. (P2 was assigned to ten small engines which went on the roster with the acquisition of the Cincinnati, Hamilton & Dayton.) Baldwin built these two classes, numbered 5100 - 5129 and 5130 - 5139, the later ten having Vanderbilt tenders, in 1913 and 1917. They were a reversion to more modest dimensions; 24 x 28 cylinders, 76 inch drivers, 210 psi boilers, 38,000 lbs te and weights off 248,500/255,500 lbs. These locomotives were basically assigned to low grade districts on the eastern and western segments of the B&O.

The next class were the USRA 4-6-2A "light" Pacifics. 30 were supplied under the USRA, class P5, 5200-5219 from Baldwin and 5220-5229 from Alco. These were delivered in 1919. P6 was Baldwin manufactured in 1923, 5530-5244, distinguished from their earlier sisters by having Vanderbilt tenders. As the B&O favored even dimensions in locomotive drive wheels, these varied from the standard USRA specifications in that respect, and also in that they had slightly higher boiler pressure, probably to compensate for the higher drivers. So, they had 25 x 28 inch cylinders, 74 inch drivers, 210 psi boilers and 40,200 lbs te. Weight of engines was 280,000/288,000 lbs. (Interesting how somehow the weight always seemed to increase with each successive reorder of a given class of steam locomotive.) Some were assigned to Washington - Philadelphia service, others to Chicago trains. However, for the most part, the district covered by P5s was the one from Parkersburg, West Virginia to St. Louis, which they did marvelously well, until the diesel. (In a similar fashion, the 100 Q-3 "light" USRA Mikados rostered by the B&O basically performed freight service on this route.

The final class of Pacific was the best known, the P-7 "President class. Up until they were built, by Baldwin in 1927, B&O trains to and from Washington, and point west, had been handled east of Philadelphia to and from Jersey City by Reading locomotives, in the post 1914 period, Pacifics. (CNJ Pacifics occasionally handled these trains.) In 1926, this arrangement was altered so that it became economically feasible for B&O power to operate east of Philadelphia.

The locomotives built for this service were 5300-5319, class P-7, built by Baldwin in 1927. Some say that they resemble the Pennsylvania K4s in specifications, my own feeling is that they were USRA 4-6-2Bs with a higher boiler pressure. (There is no argument here; one could readily say that the USRA "heavy " Pacific was a K4s with a non-Belpaire firebox, but both descended from the ALCO 50,000 mentioned earlier.) Thus, cylinders were 27 x 28, drivers 80 inch, boiler pressure 230 psi. The starting tractive effort was an impressive 50,000 lbs, and the weight 326,000 lbs. Keep in mind that the firebox/boiler specifications were basically the same as the earlier designs; thus, the impressive tractive effort could only be sustained by burning a lot of fuel. Wonderful though they might have been the P7 class was not a modern design. (However, although there were no major rebuilds which changed the basic specifications, many of the class received such aids to proper maintenance as roller bearings and one-piece engine beds, as well as boiler improvements.)

The reason for the name "President" was that they were named for the first 20 presidents of the United States. An additional locomotive, 5320, classified P9, was built by the Mt. Clare Shops in 1928. It differed from the others in that it had Caprotti valve gear and a watertube boiler. In 1947, it was rebuilt to conform to the others of the class. Some locomotives were equipped with streamline shrouds, first for the "Royal Blue", a fast Washington- Jersey City service, later for the Cincinattian, which ran between DC and Cincinnati (the first time P7s had worked through the mountains east of Cumberland and into West Virginia) and then later to the Cincinnati-Detroit run. The service between DC and Jersey City was highly competitive, and the rail competition was the mighty PRR, electrified in the 1930s, and with a direct entrance into Manhattan. Further, as we have mentioned, when the B&O was ordering new power in the 1930s, it was one of the first to dieselize. The P7 class was first limited to trains out of Philadelphia and Baltimore, then, in common with the sad remnants of B&O steam, sent further and further west, until the end. (It should be noted that the St. Louis line, with its track capacity limited to "light" USRA Pacifics and Mikados, was one of the first to be dieselized.)

Buffalo, Rochester, & Pittsburgh

The Buffalo, Rochester & Pittsburgh was not a large passenger railroad, but it did provide its ridership with the best equipment available. In the early years the railroad used the finest 4-4-0 and 4-6-0 it could buy. Later, it began using the 4-4-2 "Atlantics" with four (road numbers 160 through 163) coming in 1903 and by 1909 eleven more (road numbers 164 through 174) were added to it passenger service. These 15 locomotives were designated as Class W.

As passenger cars became heavier and trains longer the Class W locomotives were replaced by a fleet of 4-6-2 "Pacific" locomotives. The first 17 (road numbers 600 through 616) arrived from the American Locomotive Company beween 1912 and 1918 and were designated Class WW. These locomotives had 24 1/2x26 cylinders, 73" drivers, a 200 psi boiler pressure, exerted 36,340 lbs of tractive effort and each weighed 258,000 pounds. In 1923 another five (road numbers 675 through 679) were delivered from ALCO and were designated as Class WW-2. They had 22 1/2x28 cylinders, 73" drivers, a 200 psi boiler pressure, exerted 33,000 lbs of tractive effort and each weighed 241,000 pounds.

In 1932 the Baltimore & Ohio took over the BR&P and renumbered both classes of the WW locomotives. All of the BR&P "Pacific" were retired by 1953 and there are no survivors.


Roster by Richard Duley

B&O ClassQty.Road NumbersLater NumbersLater NumbersYear BuiltBuilder
P352100-21345000-50345150-51841906ALCO
P-1102135-21445050-50591911Baldwin
P-1a302145-21755060-50891911Baldwin
P-1c305000-50091924B&O
5035-5049
5090-5092
5093 & 5094
P-3305100-51291913Baldwin
P-4105130-51391917Baldwin
P-5205200-52191919Baldwin
P-5105220-52291919ALCO
P-6155230-52441923Baldwin
P-7205300-53191927Baldwin
P-9153201928B&O

BR&P ClassQty.Road NumbersB&O NumbersYear BuiltBuilder
WW3600-6025140-51421912ALCO
WW6603-6085143-51481913ALCO
WW8609-6165185-51921918ALCO
WW-25675-6795260-52641923ALCO

Class Details by Steve Llanso of Sweat House Media

Class P (Locobase 5695)

Data from B & O to 1954 Asstd Loco Diagrams book supplied in May 2005 by Allen Stanley from his extensive Raildata collection and Alvin F Staufer & Lawrence W Sagle, B & O Power (1964).

Drury (1993) lays out the tangled threads of locomotive family life in this class ID: "... most were P-1a, actually, and classification gets confusing here, with P-1 converted to P-1aa, P-1 and P-1a converted to P-1ba, and at least 30 converted from Mikados [see P-1d - SLl]. Generally the P-1 was the mainstay of B&O passenger service." Most were later superheated.


Class P-1 - 2135 (Locobase 2884)

Data from B & O to 1954 Asstd Loco Diagrams book supplied in May 2005 by Allen Stanley from his extensive Raildata collection and Alvin F Staufer & Lawrence W Sagle, B & O Power (1964). See also DeGolyer, Volume 35, p. 40+; and "Powerful Freight and Passenger Locomotives", American Engineer and Railroad Journal, Volume 85, No.4 (April 1911), p. 143-144. Works numbers were 35903-35910 in January 1911; 36008-36009 in February.

Drury (1993) lays out the tangled threads of locomotive family life in this class ID: "... most were P-1a, actually, and classification gets confusing here, with P-1 converted to P-1aa, P-1 and P-1a converted to P-1ba, and at least 30 converted from Mikados [see P-1d -Locobase]. Generally the P-1 was the mainstay of B&O passenger service."

See Locobase 1037 for the 2-8-2 design that used the same boiler. These engines showed an unusually long stroke for a Pacific -- another result of sharing many design elements with the Q-1 Mikados. Although some conversions included shortening the stroke to 28", most retained the longer stroke. The Ps also had the larger 14" (356 mm) piston valves.

Only these 10 were delivered without superheaters and they were later converted to P1-aa (Locobase 9609).


Class P-1A/P-1C - 1919 (Locobase 9610)

Data from B & O to 1954 Asstd Loco Diagrams book supplied in May 2005 by Allen Stanley from his extensive Raildata collection and Alvin F Staufer & Lawrence W Sagle, B & O Power (1964).

Firebox heating surface included 28 sq ft of arch tubes; cylinders were served by 14" piston valves. This class of conversions from Q-1 series 2-8-2s (Locobases 1037 and 3096), adopted a shorter 28" piston stroke and the 34-element superheater that served most B & O Pacifics. (A few P-1As, which had retained the 32" stroke, were also made over and grouped with this class.)


Class P-1a (Locobase 9604)

Data from B & O to 1954 Asstd Loco Diagrams book supplied in May 2005 by Allen Stanley from his extensive Raildata collection and Alvin F Staufer & Lawrence W Sagle, B & O Power (1964). See also DeGolyer, Volume 38, p. 148+. Works numbers were 36849-36852, 36922-36930, 36943-36947, 36981-36987, 36991-36993 in September; 37014-37015 in October

It didn't take Daniel Willard very long at all to realize that buying modern locomotives with saturated boilers reflected a needless conservatism. Within months of taking delivery of the P-1as shown in Locobase 2884, he procured 30 more of the same design with superheaters. Firebox heating surface included 28 sq ft (2.6 sq m) of arch tubes. The design introduced the 14"(356 mm) piston-valve, Walschaert-radial-valve-gear, 74" driver, boiler-and-superheater combination that would serve most B & O Pacifics that followed as well as most conversions.


Class P-1aa (Locobase 9609)

Data from B & O to 1954 Asstd Loco Diagrams book supplied in May 2005 by Allen Stanley from his extensive Raildata collection and Alvin F Staufer & Lawrence W Sagle, B & O Power (1964).

Firebox heating surface included 28 sq ft (2.6 sq m) of arch tubes and 14" (356 mm) piston valves admitted steam to the cylinders. Converted from P-1 in 1913, retaining the long stroke, but increasing cylinder diameter and adding a superheater. The diagram shows two sizes of superheater; the specifications refer to the larger of the two installations. The smaller of the two appears in the P-1A/P-1C entry (Locobase 9610).


Class P-1ba (Locobase 9605)

Data from B & O to 1954 Asstd Loco Diagrams book supplied in May 2005 by Allen Stanley from his extensive Raildata collection and Alvin F Staufer & Lawrence W Sagle, B & O Power (1964).

Firebox heating surface included 28 sq ft of arch tubes.


Class P-1d (Locobase 9611)

Data from B & O to 1954 Asstd Loco Diagrams book supplied in May 2005 by Allen Stanley from his extensive Raildata collection and Alvin F Staufer & Lawrence W Sagle, B & O Power (1964).

Firebox heating surface included 28 sq ft of arch tubes. This was the final makeover for many of the P-1 and P-1a engines. Boiler pressure grew to 225 psi and adhesive weight rose to an even 100 short tons. Sagle & Staufer note that the P-1ds (and P-1cs) were the B & O's primary passenger power in the mountains.


Class P-1d -watertube (Locobase 126)

Data from B & O to 1954 Asstd Loco Diagrams book supplied in May 2005 by Allen Stanley from his extensive Raildata collection and Alvin F Staufer & Lawrence W Sagle, B & O Power (1964).

Firebox heating surface included 28 sq ft of arch tubes.

Sagle says these were converted from earlier Mikados by the B&O. Railway Age (11 July 1931) published the data in this entry, but gave few details. The data shown in the specs represent the semi-watertube fireboxes fitted to some of the class.


Class P-2 (Locobase 2049)

Data from B & O to 1954 Asstd Loco Diagrams book supplied in May 2005 by Allen Stanley from his extensive Raildata collection and Alvin F Staufer & Lawrence W Sagle, B & O Power (1964).

The only class of true express engines on the Cincinnati, Hamilton, & Dayton, these Pacifics were originally delivered in 1910 with 22" x 30" cylinders and a BP of 200 lb -- TE was 27,200 lb. Apparently, the long stroke posed a problem (possibly hammer blow on the rails caused by difficulties in counterbalancing the long main rods) because they were rebuilt by 1919 with a 4" shorter stroke. TE actually went up because the boiler pressure was increased. At that point, they were given B&O numbers 5090 to 5094. For some reason, these were changed in 1924 to 5095-5099.

They ran until 1948.


Class P-3 (Locobase 1247)

Data from B & O to 1954 Asstd Loco Diagrams book supplied in May 2005 by Allen Stanley from his extensive Raildata collection and Alvin F Staufer & Lawrence W Sagle, B & O Power (1964). See also DeGolyer, Volume 47, pp. 149+.Works numbers were 40259-40262, 40295-40296, 40335-40338, 40363-40364, 40409-40421 in August 1913; 40508-40512 in September.

Had power reverse but no mechanical stokers and the firebox heating surface area included 22.6 sq ft (2.1 sq m) in four arch tubes. They were originally put to work pulling through passenger trains over a mountainous profile. Fourteen inch (356 mm) piston valves supplied the steam to the cylinders.

10 others, 5130-5139 built by Baldwin in 1917, were virtually identical, but designated P-4; see Locobase 9612. Out of service by 1952.


Class P-4 (Locobase 9612)

Data from B & O to 1954 Asstd Loco Diagrams book supplied in May 2005 by Allen Stanley from his extensive Raildata collection and Alvin F Staufer & Lawrence W Sagle, B & O Power (1964). See also DeGolyer, Volume 55, pp. 369+. (Thanks to Chris Hohl for his 26 February 2016 email noting that "as-built" cylinder diameter, steam pressure setting, and tender capacity.) Works numbers were 46156-46157, 46165 in August 1917; 46275-46276 in September; 46966 in November; 47475 in December; 47538, 47651 in January 1918; and 47795 in February.

This decade of Pacifics were repeats of the 1913 P-3 class (see Locobase 1247) and, as so often happened with such do-agains, were heavier. Even at that weight, however, this design was still one of the smallest 4-6-2s to be built during that period, especially in the size of the boiler. The firebox heating surface area includes 25.6 sq ft (2.4 sq m) in four arch tubes. Piston valves were 14" (356 mm) in diameter.

Note that Baldwin's specs note that the boiler's tested pressure was 210 psi "with a factor of safety of 4.5"; the railroad would later reset the working steam pressure to that figure. Tender capacity increased to 16.5 tons (14,969 kg) in 1926 and the shops enlarged cylinder diameters to 24" in 1927. This was also the year the road reduced the front truck wheel diameters from 36"(914 mm) to 33"(838 mm). Weight increased to 165,100 lb (74,888 kg) on the drivers and 255,500 (115,893 kg) for the engine.

A 29 August 1917 letter from the B&O's A A Sandman (Volume 55, p. 383) said that Baldwin's calculations of counterbalance weight divided the weight of the main rod to allocate 54.1% of the weight to the rear and 45.9% to the front and did not account for the rear end of the eccentric rod. According to Sandman, this ran contrary to B&O practice. He included a table of Baldwin weights and the B&O's preferred weights and asked that Baldwin apply the counterbalances according to the B&O's wishes. The table showed the result shift in weights to the middle pair of drivers that resulted.

The firebox heating surface area includes 25.6 sq ft (2.4 sq m) in four arch tubes. Piston valves were 14" (356 mm) in diameter. Tender coal capacity increased to 16.5 tons (14,969 kg) in 1926.


Class P-5 (Locobase 1249)

Data from 1930 BR & P locomotive diagram book supplied in May 2005 by Allen Stanley from his extensive Raildata collection and Alvin F Staufer & Lawrence W Sagle, B & O Power (1964).

This was the "light" Pacific design standardized by the government-run USRA created in World War I and built by Baldwin (20) and Alco-Richmond (10). Compared to other B&O designs, these were plush engines, being fitted with power reverse, grate shakers, and coal pushers. 20 in the class later received Walschaert valve gear and redesignated P-5a. Steam pressure in all later rose to 210 psi. All had retired by 1956.


Class P-6A (Locobase 1248)

Data from B & O to 1954 Asstd Loco Diagrams book supplied in May 2005 by Allen Stanley from his extensive Raildata collection and Alvin F Staufer & Lawrence W Sagle, B & O Power (1964). See also DeGolyer, Volume 58, pp. Works numbers were 55717-55718 in November 1922, 55876-55888 in December.

These were based on the USRA's Light Pacific design. Had hand screw reverse and coal pushers (to bring the coal to the front of the tender) but no mechanical stokers. Firebox heating surface area included 46 sq ft (4.3 sq m) of combustion chamber area and 34 sq ft (3.15 sq m) in arch tubes.

When they entered service, the P-6s had Baker valve gear actuating 14" (356 mm) piston valves.

In 1932, they were fitted with Walschaert valve gear and the BP rose from 200 to 210 psi. At that point they were redesignated P-6a and the specifications describe this upgrade.

Three (5233-5234) were scrapped in June 1951, 5240 was scrapped in June 1954, and the rest were retired in 1955-1957.


Class P-7 (Locobase 127)

Data from tables in 1930 Locomotive Cyclopedia and Alvin F Staufer & Lawrence W Sagle, B & O Power (1964). See also DeGolyer, Volume 77, pp. 302+. Works numbers were 59881-59886 in February 1927, 59928-59937, 59973-59976 in April.

As built, the firebox had combustion chamber, 81 sq ft (7.5 sq m) of thermic syphons, and 14 sq ft (1.3 sq m) of arch tubes. Fourteen-inch (356 mm) piston valves admitted steam to the nearly square cylinder volume.

Powerful fleet of 20 passenger engines named after US Presidents (in order, beginning with #5300 President Washington).

Note that 5320--President Cleveland--was a P-7 completed in Mt. Clare shops to watertube boiler design and fitted with Caprotti rotary valve gear. Its class ID was P-9. First of the unconventional features to be jettisoned was the poppet gear, which was replaced by Walschaert gear in 1929. At the same time, a tweaked watertube firebox design led to the 5320's redesignation as P-9a.

5310 was converted in 1939 to watertube firebox and streamlined for service on the Royal Blue. It regained its conventional firebox in 1945.

Sagle, 1964, provides details on several rebuilding programs, but in summary they were as follows:

5306 became a P-7b in 1942 when she was fitted with a B&O-designed Type R superheater; see Locobase 9380.

Four engines -- 5305, 5308-5309, 5318 -- were rebuilt as P-7c in 1944-45; see Locobase 9381.

Similar rebuilds were wrought on several more P-7s. P-7d covered four converted streamliners; see Locobase 14452.

Four different firebox designs appeared on the P-7e, a designation applied in 1949: 5314 had the simplest rework, gaining thermic syphons and two arch tubes; 5315 got a syphon, five arch tubes, and a combustion chamber; 5317 had Nicholson circulators; and 5312, 5316, and 5319 received the semi-watertube fireboxes fitted to the 5309 and 5318. All also were refitted with cast-steel beds, Timken roller bearings on all axles, and a Worthington feed water heater.

The last P-7 retired in 1958.


Class P-7a (Locobase 15923)

Data from B&O to 1954 Assorted Diagrams supplied in May 2005 by Allen Stanley from his extensive Raildata collection.. (Thanks to Chris Hohl for his 16 September 2015 email and spreadsheet noting the intermediate streamlining on this engine that led to this separate entry.)

Locobase 127 shows the Baldwin-built P-7 class of Pacifics as they were delivered in 1927. As noted in 127, 5320 was completed with a full watertube firebox. This entry shows the 5304 in 1937 as she received a new semi-watertube firebox and streamlining to befit her duty as an engine pulling The Royal Blue premium express service. The casing featured a rounded conical nose, shrouded top line, masked cylinders, but open running gear.

The firebox's heating surface area now had 57 sq ft (5.3 sq m) of troughs, 51 sq ft in circulating tubes (4.75 sq m), 29 sq ft (2.7 sq m) in arch tubes.

The streamline casing was removed in 1940 and the 5304's designation reverted to P-7. Its semi-water tube firebox was exchanged for a conventional furnace in 1947; see Locobase 14452.


Class P-7b (Locobase 9380)

Data from B & O to 1954 Asstd Loco Diagrams book supplied in May 2005 by Allen Stanley from his extensive Raildata collection and Alvin F Staufer & Lawrence W Sagle, B & O Power (1964).

5306 was delivered in 1927 as part of the 20-locomotive P-7 class produced by Baldwin (Locobase 127). It became a P-7b in 1942 when it was fitted with a B&O-designed Type R superheater. The specifications above show the locomotive after it was equipped with a semi-watertube boiler that subdivided heating surface into 293 sq ft for the sheets, 29 sq ft in arch tubes, 57 sq ft in troughs, and 51 sq ft in side tubes.


Class P-7c (Locobase 9381)

Data from B & O to 1954 Asstd Loco Diagrams book supplied in May 2005 by Allen Stanley from his extensive Raildata collection and Alvin F Staufer & Lawrence W Sagle, B & O Power (1964).

These four engines -- 5305, 5308-5309, 5318 -- had their boilers remounted on solid-steel engine beds with integrally cast cylinders. Other changes included feedwater heaters, a front-deck shield around several pumps and pipes, and a lowered headlight. Firebox heating surface then included 14 sq ft of arch tubes and 70 sq ft of thermic syphons.

Two of the four -- 5309 and 5318 -- were fitted with semi-watertube fireboxes that provided a total of 429 sq ft of heatings surface. Both engine and tender trucks received roller bearings in 1951.


Class P-7d (Locobase 14452)

Data from B&O Assorted to 1954 Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Raildata collection. See also Jeffrey Wimberly's account "The Baltimore and Ohio Railroad-the Cincinnatian", archived at http://jeffreywimberly.proboards.com/index.cgi?board=boci&action=print&thread=1497. (Thanks to Chris Hohl for his email pointing me toward the streamlining program described below.)

In 1946, four streamlined P-7d were assigned to the new all-coach Cincinnatian, a full-service, all-coach train between Cincinnati and Baltimore. The train's design was the product of Ms Olive Wetzel Dennis, a B&O "engineer of service" who was the first woman member of the American Railway Engineering Association. According to her biography at Engineer Girl (http://www.engineergirl.org/?id=11835): "She invented and held the patent for the Dennis ventilator, which was in the windows of passenger cars and could be controlled by passengers. She also played a major role in air-conditioning the coaches, dimming overhead lights, reclining individual seats, and creating stain-resistant upholstery."

The class's locomotive casing design is described as stemming from the ideas of Otto Kuhler, well-known designer in the streamline era. Dennis had a more direct influence on the coaches themselves. Putting ten cars through an overhaul equal to that of the locomotives, the B&O emerged with two five-car trains. Each had" a baggage-coffee shop-lounge, three coaches, and an observation car with a dining room and stainless steel kitchen. Two of the three coaches seated 60 passengers, the third seating 56, and was equipped with stewardess-nurse room. The cars were painted in royal blue, gray, and black with yellow trim and accents. All of the cars were air conditioned and had reclining seats."

Cosmetic embellishments on the locomotives included a hemispherical smokebox cap, front end shrouding, parallelogram striping, a steamboat whistle, and "Bando Blue"paint. The P-7d and the P-7e also had the new frames of the P-7c. In addition, all axles were fitted with Timken roller bearings and the engines now had Worthington feed water heaters. All of this added some weight and the axle loading of 70,000+ pounds put the engines in the top rank. All four had 28 sq ft of arch tubes (2.6 m), but 5303, for some reason, didn't get the other firebox accessories: 57 sq ft of "troughs" (5.3 sq m) and 51 sq ft of side tubes (4.7 sq m).

Such was the quality of locomotive service that the B&O could run the two trains with three locomotives. Westbound #75 would stop at Grafton, West Virginia and the locomotive would be swapped for one that took the train to Cincinnati. Meanwhile, the just-idled engine would be serviced in 40 minutes, then coupled to eastbound #76 for its run to Baltimore. The locomotive that had just come off the 76 would remain in Grafton overnight.

The 12 1/2-hour run may have been sprightly enough, but from the time the train began service on 19 January 1947, the Cincinnatian simply draw enough riders on its original route. On June 25, 1950, the two trains began service between Cincinnati and Detroit, where ridership kept it in business until the 1971 takeover of passenger service by Amtrak.


Class P-8 (Locobase 2080)

Data from B & O to 1954 Asstd Loco Diagrams book supplied in May 2005 by Allen Stanley from his extensive Raildata collection and Alvin F Staufer & Lawrence W Sagle, B & O Power (1964).

Renumbered by the B&O as 5196-5199 and run until 1952. According to Sagle 1964, the engines resembled the New York Central's K-11 class Pacific. Locobase finds them to be more like the Monon's K-5s of 1923 (Locobase 8292). Modestly powered, they used 12" diameter piston valves for steam admission.


Class PA (Locobase 9606)

Data from B & O to 1954 Asstd Loco Diagrams book supplied in May 2005 by Allen Stanley from his extensive Raildata collection and Alvin F Staufer & Lawrence W Sagle, B & O Power (1964).

This was the first of the B & O's Pacific conversions to a superheated design. The shops retained the P class's relatively small cylinders, 12"(305 mm) piston valves actuated by Stephenson link motion, and tall drivers. Over half the class was so treated: 5000-5002, 5006-5007,5010, 5014, 5016, 5018-5019, 5021-5022, 5024, 5027-5028, 5030-5032. Boiler pressure in some of the PAs later dropped to 203 psi, a peculiarly precise setting that resulted in 929 lb (421 kg) less starting tractive effort.

Preceded only by the Ps, this class had been retired by 1946.


Class PB (Locobase 9607)

Data from B & O to 1954 Asstd Loco Diagrams book supplied in May 2005 by Allen Stanley from his extensive Raildata collection and Alvin F Staufer & Lawrence W Sagle, B & O Power (1964).

As the B & O continued its superheater-oriented upgrade of its early Pacifics, it adopted two sizes of superheater installations. Most P-class 4-6-2s received the smaller package of 25 elements and retained the 22"-diameter cylinders and Stephenson link motion; see Locobase 9606 for these Pa-class engines.

In the early 1920s however, four were upgraded with 24"-diameter cylinders. Two of these had 34-element superheaters; classed as Pc, these are shown in Locobase 9608. The other two appear in this entry. Admitting steam through the now-standard 14"-diameter piston valves using Walschaert radial valve gear, these engines had their boilers set at a lower pressure than the Pa class.

Both engines were retired in 1949.


Class PC (Locobase 9608)

Data from B & O to 1954 Asstd Loco Diagrams book supplied in May 2005 by Allen Stanley from his extensive Raildata collection and Alvin F Staufer & Lawrence W Sagle, B & O Power (1964).

As noted in Locobase 9607, the B & O shops took four P-class saturated-steam Pacifics and gave them larger cylinders and 14"-piston valves. Two retained the small, 25-element superheater and were classed Pb. The two in this entry adopted the larger 34-element superheater then being fitted in most B & O 4-6-2s. As a result, these may have been the "driest" passenger engines on the road. They also used Baker valve gear.

So equipped, the PCs remained in service until 1950.


Class WW (Locobase 2063)

Data from 1930 BR & P locomotive diagram book supplied in May 2005 by Allen Stanley from his extensive Raildata collection and Alvin F Staufer & Lawrence W Sagle, B & O Power (1964).

Sturdy, conventional Pacifics with extended piston rods, 14" (356 mm) piston valves, and, as Drury (1993) notes, an "undersized trailing truck frame" that in a photo looks toylike. The firebox heating surface included 27 sq ft of arch tubes. The 4-6-2s shared the boiler design with the 2-8-2s supplied in the same year (Locobase 2066).

These lasted until 1953 in B&O service, where they were reclassed P-17/P-17a/P-18/P-18a and renumbered 5140-5148, 5185-5192.


Class WW-2 / P-19 (Locobase 2065)

Data from 1930 BR & P locomotive diagram book supplied in May 2005 by Allen Stanley from his extensive Raildata collection. Works numbers were 64589-64593 in August 1923.

Locobase estimates the superheater area, which is not given separately, from several other US locomotives with identical superheater layouts and flue lengths.

Smaller, lighter Pacifics that rounded out the BR&P's heavily used passenger stud. Drury (1993, 433) has a typical 1930 schedule.

In B&O service, they were P-19 (5260-5264) and lasted until 1953. Sagle 1964.

Specifications by Steve Llanso of Sweat House Media
ClassPP-1 - 2135P-1A/P-1C - 1919P-1aP-1aa
Locobase ID5695 2884 9610 9604 9609
RailroadBaltimore & Ohio (B&O)Baltimore & Ohio (B&O)Baltimore & Ohio (B&O)Baltimore & Ohio (B&O)Baltimore & Ohio (B&O)
CountryUSAUSAUSAUSAUSA
Whyte4-6-24-6-24-6-24-6-24-6-2
Number in Class3540303128
Road Numbers2100-2134/5000-5034/5150-51842135-2144/5050-50892145-2174/5060-50895050-5059
GaugeStdStdStdStdStd
Number Built354031
BuilderAlco-SchenectadyBaldwinB&OBaldwinB&O
Year19061911191919111913
Valve GearStephensonWalschaertWalschaertWalschaertWalschaert
Locomotive Length and Weight
Driver Wheelbase13.17'13'13'13'13'
Engine Wheelbase34.29'34.67'34.67'34.67'34.67'
Ratio of driving wheelbase to overall engine wheebase 0.38 0.37 0.37 0.37 0.37
Overall Wheelbase (engine & tender)66.39'70.89'70.87'70.87'70.87'
Axle Loading (Maximum Weight per Axle)66000 lbs59600 lbs66000 lbs
Weight on Drivers150500 lbs166200 lbs191000 lbs172000 lbs194000 lbs
Engine Weight229000 lbs263800 lbs289002 lbs277100 lbs308500 lbs
Tender Light Weight147000 lbs176200 lbs192000 lbs192000 lbs192000 lbs
Total Engine and Tender Weight376000 lbs440000 lbs481002 lbs469100 lbs500500 lbs
Tender Water Capacity7000 gals9500 gals9500 gals9500 gals9500 gals
Tender Fuel Capacity (oil/coal)15 tons16 tons19.5 tons19.5 tons19.5 tons
Minimum weight of rail (calculated)84 lb/yard92 lb/yard106 lb/yard96 lb/yard108 lb/yard
Geometry Relating to Tractive Effort
Driver Diameter74"74"74"74"74"
Boiler Pressure225 psi205 psi190 psi205 psi210 psi
Cylinders (dia x stroke)22" x 28"24" x 32"26" x 28"24" x 32"26" x 32"
Tractive Effort35025 lbs43402 lbs41309 lbs43402 lbs52180 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.30 3.83 4.62 3.96 3.72
Heating Ability
Firebox Area179.40 sq. ft228 sq. ft256 sq. ft256 sq. ft281 sq. ft
Grate Area56.24 sq. ft78 sq. ft70 sq. ft70 sq. ft70 sq. ft
Evaporative Heating Surface3414 sq. ft5017 sq. ft3980 sq. ft3980 sq. ft3819 sq. ft
Superheating Surface811 sq. ft811 sq. ft955 sq. ft
Combined Heating Surface3414 sq. ft5017 sq. ft4791 sq. ft4791 sq. ft4774 sq. ft
Evaporative Heating Surface/Cylinder Volume277.13299.43231.31237.54194.21
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation1265415990133001435014700
Same as above plus superheater percentage1265415990155611679017640
Same as above but substitute firebox area for grate area4036546740569096140270812
Power L197119291171041895118201
Power MT426.76369.73592.27728.72620.51

Specifications by Steve Llanso of Sweat House Media
ClassP-1baP-1dP-1d -watertubeP-2P-3
Locobase ID9605 9611 126 2049 1247
RailroadBaltimore & Ohio (B&O)Baltimore & Ohio (B&O)Baltimore & Ohio (B&O)Cincinnati, Hamilton & Dayton (B&O)Baltimore & Ohio (B&O)
CountryUSAUSAUSAUSAUSA
Whyte4-6-24-6-24-6-24-6-24-6-2
Number in Class52930530
Road Numbers5080, 50895000-5009, 5035+501-5055100-5129
GaugeStdStdStdStdStd
Number Built30530
BuilderB&OB & OB & OAlco-SchenectadyBaldwin
Year19241929192419101913
Valve GearWalschaertWalschaertBakerWalschaertWalschaert
Locomotive Length and Weight
Driver Wheelbase13'13'13'13.33'13.17'
Engine Wheelbase34.17'34.17'34.67'33.83'34.29'
Ratio of driving wheelbase to overall engine wheebase 0.38 0.38 0.37 0.39 0.38
Overall Wheelbase (engine & tender)70.96'76.46'66.04'65.71'
Axle Loading (Maximum Weight per Axle)66000 lbs67500 lbs67500 lbs55100 lbs
Weight on Drivers191000 lbs200000 lbs200000 lbs141750 lbs159200 lbs
Engine Weight317000 lbs317000 lbs317000 lbs221700 lbs248000 lbs
Tender Light Weight192000 lbs232000 lbs236000 lbs168800 lbs165000 lbs
Total Engine and Tender Weight509000 lbs549000 lbs553000 lbs390500 lbs413000 lbs
Tender Water Capacity9500 gals13500 gals13500 gals8000 gals7000 gals
Tender Fuel Capacity (oil/coal)18.5 tons19 tons19 tons16.5 tons14 tons
Minimum weight of rail (calculated)106 lb/yard111 lb/yard111 lb/yard79 lb/yard88 lb/yard
Geometry Relating to Tractive Effort
Driver Diameter74"74"74"77"76"
Boiler Pressure215 psi225 psi225 psi210 psi210 psi
Cylinders (dia x stroke)26" x 28"26" x 28"26.5" x 28"22" x 26"24" x 28"
Tractive Effort46744 lbs48919 lbs50818 lbs29172 lbs37880 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.09 4.09 3.94 4.86 4.20
Heating Ability
Firebox Area286 sq. ft256 sq. ft329 sq. ft152 sq. ft207.60 sq. ft
Grate Area70 sq. ft70 sq. ft70 sq. ft43.90 sq. ft56.49 sq. ft
Evaporative Heating Surface3819 sq. ft3962 sq. ft4035 sq. ft2573 sq. ft2544 sq. ft
Superheating Surface955 sq. ft859 sq. ft859 sq. ft608 sq. ft587 sq. ft
Combined Heating Surface4774 sq. ft4821 sq. ft4894 sq. ft3181 sq. ft3131 sq. ft
Evaporative Heating Surface/Cylinder Volume221.96230.27225.74224.93173.52
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation150501575015750921911863
Same as above plus superheater percentage1806018585185851097114117
Same as above but substitute firebox area for grate area7378867968873503798551879
Power L12133520923208212074416084
Power MT738.78691.91688.54967.89668.20

Specifications by Steve Llanso of Sweat House Media
ClassP-4P-5P-6AP-7P-7a
Locobase ID9612 1249 1248 127 15923
RailroadBaltimore & Ohio (B&O)Baltimore & Ohio (B&O)Baltimore & Ohio (B&O)Baltimore & Ohio (B&O)Baltimore & Ohio (B&O)
CountryUSAUSAUSAUSAUSA
Whyte4-6-24-6-24-6-24-6-24-6-2
Number in Class103015201
Road Numbers5130-51395200-52295230-52445300-53195304
GaugeStdStdStdStdStd
Number Built10301520
BuilderBaldwinSeveralBaldwinBaldwinB&O
Year19171919192219271937
Valve GearWalschaertBakerBakerWalschaertWalschaert
Locomotive Length and Weight
Driver Wheelbase13.17'13'13'14'14'
Engine Wheelbase34.29'34.75'34.92'37.08'37.08'
Ratio of driving wheelbase to overall engine wheebase 0.38 0.37 0.37 0.38 0.38
Overall Wheelbase (engine & tender)70.50'68.62'71.15'72.50'83'
Axle Loading (Maximum Weight per Axle)53000 lbs58000 lbs59200 lbs68000 lbs70000 lbs
Weight on Drivers159000 lbs172500 lbs174000 lbs201000 lbs207000 lbs
Engine Weight251000 lbs277000 lbs288600 lbs326000 lbs340000 lbs
Tender Light Weight189200 lbs240000 lbs198000 lbs218000 lbs239500 lbs
Total Engine and Tender Weight440200 lbs517000 lbs486600 lbs544000 lbs579500 lbs
Tender Water Capacity9000 gals10000 gals10000 gals11000 gals13000 gals
Tender Fuel Capacity (oil/coal)16.5 tons16 tons16 tons17.5 tons19.5 tons
Minimum weight of rail (calculated)88 lb/yard96 lb/yard97 lb/yard112 lb/yard115 lb/yard
Geometry Relating to Tractive Effort
Driver Diameter76"73"74"80"80"
Boiler Pressure190 psi200 psi210 psi230 psi240 psi
Cylinders (dia x stroke)23.5" x 28"25" x 28"25" x 28"27" x 28"27.5" x 28"
Tractive Effort32859 lbs40753 lbs42213 lbs49882 lbs53996 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.84 4.23 4.12 4.03 3.83
Heating Ability
Firebox Area210.60 sq. ft261 sq. ft265 sq. ft394 sq. ft429 sq. ft
Grate Area56.50 sq. ft66.70 sq. ft66.70 sq. ft70.30 sq. ft70.30 sq. ft
Evaporative Heating Surface2570 sq. ft3333 sq. ft3331 sq. ft3846 sq. ft3877 sq. ft
Superheating Surface604 sq. ft794 sq. ft794 sq. ft932 sq. ft950 sq. ft
Combined Heating Surface3174 sq. ft4127 sq. ft4125 sq. ft4778 sq. ft4827 sq. ft
Evaporative Heating Surface/Cylinder Volume182.84209.52209.39207.28201.42
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation1073513340140071616916872
Same as above plus superheater percentage1277515875166681940320246
Same as above but substitute firebox area for grate area476176211866224108744123552
Power L11551118025192152347624225
Power MT645.20691.10730.38772.47774.01

Specifications by Steve Llanso of Sweat House Media
ClassP-7bP-7cP-7dP-8PA
Locobase ID9380 9381 14452 2080 9606
RailroadBaltimore & Ohio (B&O)Baltimore & Ohio (B&O)Baltimore & Ohio (B&O)Cincinnati, Indianapolis, & Western (B & O)Baltimore & Ohio (B&O)
CountryUSAUSAUSAUSAUSA
Whyte4-6-24-6-24-6-24-6-24-6-2
Number in Class144418
Road Numbers53065305, 5308-5309, 53185301-5304121-124 / 5196-51995000+
GaugeStdStdStdStdStd
Number Built4
BuilderB&OB&OB&OAlco-SchenectadyB&O
Year19421944194619241911
Valve GearWalschaertWalschaertWalschaertWalschaertStephenson
Locomotive Length and Weight
Driver Wheelbase14'14'14'12.83'13.17'
Engine Wheelbase37.08'37.08'37.08'33.58'34.29'
Ratio of driving wheelbase to overall engine wheebase 0.38 0.38 0.38 0.38 0.38
Overall Wheelbase (engine & tender)77.50'77.50'72.50'75.46'67.58'
Axle Loading (Maximum Weight per Axle)69000 lbs69000 lbs71000 lbs53100 lbs
Weight on Drivers204000 lbs205000 lbs211000 lbs155500 lbs150500 lbs
Engine Weight332000 lbs333500 lbs347500 lbs244000 lbs229500 lbs
Tender Light Weight218000 lbs218000 lbs366000 lbs180000 lbs168800 lbs
Total Engine and Tender Weight550000 lbs551500 lbs713500 lbs424000 lbs398300 lbs
Tender Water Capacity11000 gals11000 gals20000 gals6400 gals8600 gals
Tender Fuel Capacity (oil/coal)19.5 tons19.5 tons28 tons15 tons16.5 tons
Minimum weight of rail (calculated)113 lb/yard114 lb/yard117 lb/yard86 lb/yard84 lb/yard
Geometry Relating to Tractive Effort
Driver Diameter80"80"80"73"76"
Boiler Pressure230 psi230 psi230 psi200 psi210 psi
Cylinders (dia x stroke)27" x 28"27" x 28"27" x 28"23" x 28"22" x 28"
Tractive Effort49882 lbs49882 lbs49882 lbs34494 lbs31829 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.09 4.11 4.23 4.51 4.73
Heating Ability
Firebox Area429 sq. ft379 sq. ft429 sq. ft247 sq. ft179.40 sq. ft
Grate Area70.30 sq. ft70.30 sq. ft70.30 sq. ft48.70 sq. ft56.24 sq. ft
Evaporative Heating Surface3731 sq. ft3643 sq. ft3843 sq. ft2478 sq. ft2544 sq. ft
Superheating Surface908 sq. ft908 sq. ft950 sq. ft578 sq. ft587 sq. ft
Combined Heating Surface4639 sq. ft4551 sq. ft4793 sq. ft3056 sq. ft3131 sq. ft
Evaporative Heating Surface/Cylinder Volume201.08196.33207.11184.04206.51
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation161691616916169974011810
Same as above plus superheater percentage1940319403194031159114054
Same as above but substitute firebox area for grate area1184041046041184045878644832
Power L12321822659240281611118837
Power MT752.75731.04753.17685.25827.81

Specifications by Steve Llanso of Sweat House Media
ClassPBPCWWWW-2 / P-19
Locobase ID9607 9608 2063 2065
RailroadBaltimore & Ohio (B&O)Baltimore & Ohio (B&O)Buffalo, Rochester, & Pittsburgh (B&O)Buffalo, Rochester, & Pittsburgh (B&O)
CountryUSAUSAUSAUSA
Whyte4-6-24-6-24-6-24-6-2
Number in Class22175
Road Numbers5003-50045008, 5011600-616675-679 / 5260-5264
GaugeStdStdStdStd
Number Built175
BuilderB & OB&OBrooksAlco
Year1922192219121923
Valve GearWalschaertBakerWalschaertBaker
Locomotive Length and Weight
Driver Wheelbase13.17'13.17'13'13'
Engine Wheelbase34.29'34.29'33.25'65.31'
Ratio of driving wheelbase to overall engine wheebase 0.38 0.38 0.39 0.20
Overall Wheelbase (engine & tender)67.58'67.58'65.87'
Axle Loading (Maximum Weight per Axle)58200 lbs58200 lbs61100 lbs
Weight on Drivers155000 lbs155000 lbs163500 lbs146600 lbs
Engine Weight247800 lbs247800 lbs258000 lbs241200 lbs
Tender Light Weight168800 lbs168800 lbs171500 lbs176700 lbs
Total Engine and Tender Weight416600 lbs416600 lbs429500 lbs417900 lbs
Tender Water Capacity8600 gals8600 gals9250 gals9500 gals
Tender Fuel Capacity (oil/coal)16.5 tons16.5 tons14 tons14 tons
Minimum weight of rail (calculated)86 lb/yard86 lb/yard91 lb/yard81 lb/yard
Geometry Relating to Tractive Effort
Driver Diameter76"74"73"73"
Boiler Pressure190 psi190 psi200 psi200 psi
Cylinders (dia x stroke)24" x 28"24" x 28"24.5" x 26"22.5" x 28"
Tractive Effort34272 lbs35198 lbs36344 lbs33010 lbs
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.52 4.40 4.50 4.44
Heating Ability
Firebox Area179.40 sq. ft179.40 sq. ft234 sq. ft196 sq. ft
Grate Area56.50 sq. ft56.50 sq. ft56.50 sq. ft53.60 sq. ft
Evaporative Heating Surface2544 sq. ft2680 sq. ft3625 sq. ft2813 sq. ft
Superheating Surface587 sq. ft811 sq. ft750 sq. ft650 sq. ft
Combined Heating Surface3131 sq. ft3491 sq. ft4375 sq. ft3463 sq. ft
Evaporative Heating Surface/Cylinder Volume173.52182.80255.52218.31
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation10735107351130010720
Same as above plus superheater percentage12775132041322112757
Same as above but substitute firebox area for grate area40562419265475646648
Power L114321173841980218210
Power MT611.08741.78801.03821.54

Photos

Reference


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