Class P (Locobase 5695)

Data from B & O to 1954 Asstd Loco Diagrams book supplied in May 2005 by Allen Stanley from his extensive 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 (Locobase 2884)

Data from B & O to 1954 Asstd Loco Diagrams book supplied in May 2005 by Allen Stanley from his extensive 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 -Locobase]. Generally the P-1 was the mainstay of B&O passenger service." See Locobase 1037 for the 2-8-2 design.

Most were later superheated.

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 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-1AA (Locobase 9609)

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

Firebox heating surface included 28 sq ft of arch tubes and 14" 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-1a - 1911 (Locobase 9604)

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

Firebox heating surface included 28 sq ft of arch tubes. These showed an unusually long stroke for a Pacific and it's likely that it offered problems in service as all conversions included shortening the stroke to 28". The design introduced the 14"-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-1ba (Locobase 9605)

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

Had power reverse but no mechanical stokers. 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 collection and Alvin F Staufer & Lawrence W Sagle, B & O Power (1964).

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.

Class P-5 (Locobase 1249)

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

Had hand screw reverse and coal pushers (to bring the coal to the front of the tender) but no mechanical stokers.

When they entered service, the P-6s had Baker valve gear. 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.

Out of service by 1949.

Class P-7 (Locobase 127)

Data from tables in 1930 Locomotive Cyclopedia and Alvin F Staufer & Lawrence W Sagle, B & O Power (1964).

As built, the firebox had combustion chamber, 81 sq ft of thermic syphons, and 14 sq ft of arch tubes.

Powerful fleet of 20 passenger engines named after US Presidents (in order, beginning with #5300 President Washington). #5320 completed in Mt. Clare shops to watertube boiler design and fitted with Caprotti rotary valve gear. #5310 also converted to watertube boiler and streamlined for service on the Royal Blue.

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. In 1946, four streamlined P-7d -- 5301-5304 -- were assigned to the Cincinnatian. These and the P-7e -- 5312, 5314-5317, 5319 -- also had the new frames of the P-7c. In addition, all axles were fitted with roller bearings. Four different firebox designs appeared on the P-7e: 5314 had the simplest rework, gaining thermic syphons and 2 arch tubes; 5315 got a syphon, 5 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.

The last P-7 retired in 1958.

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 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, 135 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 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-8 (Locobase 2080)

Data from B & O to 1954 Asstd Loco Diagrams book supplied in May 2005 by Allen Stanley from his extensive 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 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" 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 a 30,900 lb less 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 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, 4 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 collection and Alvin F Staufer & Lawrence W Sagle, B & O Power (1964).

As noted in Locobase 9607, the B & O shops took 4 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 collection and Alvin F Staufer & Lawrence W Sagle, B & O Power (1964).

Sturdy, conventional Pacifics with extended piston rods, 14" 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.

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 collection. 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.