Class P-1 - simpled & superheated (Locobase 8514)

Data from CB&Q Assorted Steam Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange.

Locobse 369 tells how the five-engine compound Atlantic class was an immediate success in that configuration. But most railroads were drawn toward simpler operation and superheat before too long and the Burlington followed that trend. In 1914-1915, the class was rebuilt in the West Burlington shops as simple-expansion engines. Soon after that, the boiler was reworked in the usual manner, sacrificing some portion of overall heating surface area in favor of installing a set of superheater elements. One curiosity of the diagram, however, is that the flue diameter is given as 6", as opposed to the usual 5 3/8" or 5 1/2".

Whatever the diameter, the newly recharged P-1s carried on in service for another two decades, only retiring in 1932-1933.

Class P-1-C (Locobase 369)

Data from DeGolyer, Volume 22, p 50. Works numbers were 16547-16548 in March 1899.

Tractive effort given by railroad as 16,400 lb with 84 1/2" drivers, 17,800 lb with 78" drivers. These compound locomotives had the 13 1/2-in high-pressure cylinders over the 23-in low-pressure jugs; both were fed by the same 13" (331 mm)-diameter piston valve, which was operated by inside Stephenson link motion.

Corbin & Kerka (1960, p 85-86) report that these engines were immediately satisfactory. 1591 ran almost 16 months (7 April 1899 to 30 July 1900) without general repairs and racked up 160,806 miles. 1592 hauled a 200-ton, four-car fast mail the 83 miles from Mendota, Wis to Chicago in 77 minutes.

Three other Atlantics were delivered in 1901.These had more tubes of a smaller diameter; see Locobase 12327.

Like most US compounds, these engines were rebuilt to two-cylinder simple expansion. They received 19" (483 mm) x 26" (660 mm) cylinders in 1914-1915 and were later superheated; see Locobase 8514.

Class P-1-C (Locobase 12327)

Data from a locomotive diagram published on Vernon Beck's website -- [] (accessed 22 March 2003). (NB: page 140 of the Baldwin Specification book Volume 22 held at SMU's DeGolyer Library is missing from the scanned copy in Locobase's possession.) Works numbers were 18332-18333 and 18337 in October 1900.

See Locobase 369 for a discussion of the five Atlantics that made up this class. The two described in that entry had 248 2 1/4" tubes, the current entry shows the three fitted with a few more tubes of smaller diameter. The change resulted in a reduction in overall heating surface area.

Like most US compounds, these engines were rebuilt to two-cylinder simple expansion. They received 19" x 26" cylinders in 1914-1915 and were later superheated; see Locobase 8514.

Class P-2 (Locobase 370)

Data from Vernon Beck's hosting of locomtive diagrams -- [] (visited 12 April 2003). Works numbers were 5916-5918 in March 1903, 5922-5923 in April

These express passenger locomotives had a coned boiler, inside piston valves operated by Stephenson link motion, a long leading truck, and extended smokebox. They were simple-expansion brothers to the P-2Cs with the principal additional difference of having 30.2 sq ft (2.81 sq m) of arch tubes contributing to the firebox heating surface.

See Locobases for Burlington & Missouri River - 14670, Chicago, Burlington & Quincy - 8515, and Hannibal & St Joseph - 14671

Unlike other Burlington 4-4-2s, this class was not superheated except for the three (2530-2531, 2533) that were converted to P-6-A class in 1927-1928; see Locobase 5455.

Most of the class ran from 1903 to 1930.

Class P-2 (Locobase 8515)

Data from CB&Q Assorted Steam Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. See also Angus Sinclair, Twentieth Century Locomotives (New York: Railway and Locomotive Engineering, 1904), pp. 662-664. Works numbers were 5875-5876, 5881-5887 in 1903.

A year after the six balanced-compound P-3-Cs came on the road (Locobase 2898), the Burlington began operating these stylish simple-expansion counterparts from Rogers. They used 12" (305 mm) piston valves. Sinclair noted that as they were meant to haul the Burlington No 1 and other expresses, "...that work is already cut out for these machines." Although rated at 210 psi working pressure, this class usually ran at 200.

All four railroads' P-2s soon joined together within a year under the CB&Q herald and took a common run of numbers. See Locobases for Burlington & Missouri River - 14670, Hannibal & St Joseph - 14671, and St Louis, Keokuk & Northwestern - 370

Unlike other Burlington 4-4-2s, this class was not superheated except for the three (2520-2521, 2523) that were converted to P-6-A class in 1927-1928; see Locobase 5455. They served for a long time, most not being discarded until the early-1950s.

Ten other engines in this class went to subsidiaries Burlington & Missouri River (Locobase 14670), two to the Hannibal & St Joseph (14671), and five to the St Louis, Keokuk & Northwestern (14672).

Class P-2 (Locobase 14670)

Data from American Locomotive Company negative 13334. Works numbers were 5852-5861 in December 1902.

As the six balanced-compound P-3-Cs from Baldwin came on the road (Locobase 2898), the B&MR took delivery of this decade of simple-expansion variants. Ten other engines in this class went to the Chicago, Burlington & Quincy itself, two to the Hannibal & St Joseph, and five St Louis, Keokuk & Northwestern.

See Locobases for Chicago, Burlington & Quincy - 8515, Hannibal & St Joseph - 14671, and St Louis, Keokuk & Northwestern - 370

All four railroads' P-2s soon joined together within a year under the CB&Q herald and took a common run of numbers. Unlike other Burlington 4-4-2s, this class was not superheated except for the three (2530-2531, 2533) that were converted to P-6-A class in 1927-1928; see Locobase 5455.

Class P-2 (Locobase 14671)

Data from American Locomotive Company negative 13334. Works numbers were 5888-5889 in 1903.

Rogers built twenty-five of these simple-expansion counterparts to Baldwin's balanced compounds. Eight went to Chicago, Burlington & Quincy itself, ten to the Burlington & Missouri River, and five to the St Louis, Keokuk & Northwestern. 691 was reassigned to the StLK&NW in 1903 and given road number 785

See Locobases for Burlington & Missouri River - 14670, Chicago, Burlington & Quincy - 8515, and St Louis, Keokuk & Northwestern - 370

All four railroads' P-2s eventually united under a single run of road numbers, at which point the 690 was assigned 2538. Ex-691 became 2544. 2544 was superheated in 1927; see Locobase 5455.

Class P-2-C (Locobase 4090)

Data from DeGolyer, Volume 24, p. 190. See also "Compound Atlantic Type Locomotive", American Engineer and Railroad Journal, Volume 76, No 4 (April 1902), pp. 119-120; and table in Paul T Warner's article on Atlantics in the Railway & Locomotive Historical Society Bulletin #62 (1943, p 20). Works numbers were 20118-20120, 20148, 20160-20161 in February 1902.

This was a Vauclain compound design with very tall drivers and wide firebox behind the drivers borne by an outside-frame trailing truck developed by F A Delano for a Prairie-type locomotive.. Each set of cylinders (1 HP, 1 LP) was served by a single 15" (381 mm) piston valve. Baldwin's specification described a firebox with a heating surface area of 166 sq ft (15.42 sq m) and, consequently, 3,002.5 sq ft (278.98 sq m) total evaporative heating surface area. The AERJ article, published almost simultaneously, gave the figures shown in the Locobase specs.

According to Corbin & Kerka's (1960, p 282) tables, all of these were rebuilt as P-5 simple-expansion engines in 1915-1917; see Locobase 5454.

Class P-3-C - 74" (Locobase 15962)

Data from CB & Q Asstd Steam Loco Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange and Corbin & Kerka (1960, 89). Definitive data from DeGolyer, Volume 28, pp. 60+. (Many thanks to Chris Hohl for noting two wheel diameters on the P-5 rebuilds and asking why that would be in an 18 January 2015 email. It prompted the separation of this entry into two.)

Works numbers were 26735-26736 in October 1905; 26793-26794, 26844-26845, 26910-26911 in November; and 26983-26984 in December.

Balanced compounds delivered with two different driver sizes: 78" on the first ten (Locobase 2898), 74" on the last ten shown here. Used a divided drive in which the HP cylinders inside drove on the first axle and the LP cylinders drove outside on the second. The design had a prominently necked down boiler from the first to the second course and an extended smokebox.

Hohl's inquiry also led Locobase to discover the reduction of 12 fire tubes in this second decade of engines and a concomitant decrease in heating surface area. A comparison will show that the difference didn't amount to a huge figure.

Both batches were delivered with heavy 154,200 lb (69,944 kg) tenders capable of carrying 8,000 US gallons (30,280 litres). A note in the second batch (DeGolyer, Volume 28, p.60) says that they were "not intended to be used behind these balanced compound locomotives" but rather behind freight engines whose tenders would be swapped for them.

Later rebuilt as P-5 simples.

Corbin & Kerka report that July 1904 tests with the lead engine -- 2700 -- yielded results such as 42.24 mph average over a 143-mile distance (McCook, Neb to Akron, Col pulling a 580-ton train. A continuous run from Creston to Chicago (393 miles) took 9 hours, an average of 43.67 mph. These are impressive performances: Few passenger engines in any country could go so far at a decent average speed pulling so heavy a trailing load in 1904.

All of the P-3-Cs were rebuilt as P-5 or P-6 simple-expansion in the mid-1920s. See Locobase 5454 and 5455, respectively.

Class P-3-C - 78" (Locobase 2898)

Data from CB & Q Asstd Steam Loco Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange and Corbin & Kerka (1960, 89). Definitive data from DeGolyer, Volume 27, pp. 190+. (Many thanks to Chris Hohl for noting two wheel diameters on the P-5 rebuilds and asking why that would be in an 18 January 2015 email. It prompted the separation of this entry into two.)

Works numbers were 24219 in May 1904; 24644 in August; 24651-24652, 24672, 24680-24682, 24694, 24705 in September.

Balanced compounds delivered with two different driver sizes: 78" on the first ten, 74" on the last ten shown in Locobase 15965. Used a divided drive in which the HP cylinders inside drove on the first axle and the LP cylinders drove outside on the second. The design had a prominently necked down boiler from the first to the second course and an extended smokebox.

Both batches were delivered with heavy 154,200 lb tenders capable of carrying 8,000 US gallons. A note in the second batch (DeGolyer, Volume 28, p.60) says that they were "not intended to be used behind these balanced compound locomotives" but rather behind freight engines whose tenders would be swapped for them.

Later rebuilt as P-5 simples.

Corbin & Kerka report that July 1904 tests with the lead engine -- 2700 -- yielded results such as 42.24 mph average over a 143-mile distance (McCook, Neb to Akron, Col pulling a 580-ton train. A continuous run from Creston to Chicago (393 miles) took 9 hours, an average of 43.67 mph. These are impressive performances: Few passenger engines in any country could go so far at a decent average speed pulling so heavy a trailing load in 1904.

All of the P-3-Cs were rebuilt as P-5 or P-6 simple-expansion in the mid-1920s. See Locobase 5454 and 5455, respectively.

Class P-4 (N-1) (Locobase 5453)

Data from a locomotive diagram published on Vernon Beck's website -- [] (accessed 22 March 2003).

This single Atlantic was "entirely rebuilt" from the single 2-4-2 N-1 described in Locobase 423, according to the 1912 diagram referred to above. I'll say. A comparison of all the major dimensions except the cylinders and their 10" (254 mm) piston valves shows a very different locomotive even from the 1897 enlargement and reconfiguration described in the earlier entry.

This rebuild probably extended the life of the frame and cylinders for another two decades until 1929. On the other hand, the CB&Q apparently never considered adding a superheater.

Class P-5 (Locobase 5454)

Data from a locomotive diagram published on Vernon Beck's website -- [] (accessed 22 March 2003). (Many thanks to Chris Hohl for noting two wheel diameters on the P-5 rebuilds and asking why that would be in an 18 January 2015 email.)

The Burlington Route seems to have prized its Atlantics, rebuilding them for more service when other railroads simply scrapped them.

These were rebuilds of six P-2-Cs -- Locobase 4090 -- in 1915-1917 and 14 P-3-Cs -- Locobases 2898 and 15962 -- in 1924-1927 Atlantics that added superheating, 12" piston valves. The firebox heating surface included 20.29 sq ft(1.89 sq m) in three arch tubes. Note the considerable growth in weight on the drivers. All but the last seven (2566, etc) had 78" drivers; the last seven were delivered with 74" (1,880 mm) drivers and retained them. Their starting tractive effort was 27,660 lb (12,546 kg).

This class of simpled former compounds lasted into the 1940s. One retired as late as 1953.

Class P-6/P-6A (Locobase 5455)

Data from a locomotive diagram published on Vernon Beck's website -- [] (accessed 22 March 2003). (Thanks to Chris Hohl for his 18 January 2015 email pointing out the use of two different tenders.)

These were rebuilds of six P-3 (P-6) and eight P-2s (P-6A) in 1927-1928 that were very similar to the P-5s updated at the same time (Locobase 4090), but with even more weight on the drivers, and an unusually high 15 1/2" (394 mm) reduction in driver diameter. Improvements included superheating, 12" (305 mm) piston valves. The firebox heating surface included 20.29 sq ft (1.89 sq m) of three arch tubes. All of their data agreed except for tender capacities. The six P-6 tenders carried 8,000 gallons of water and 13 tons of coal; the other eight trailed the slightly less capacious tenders shown here.

All of them endured in service until the late 1940s with the last leaving the railroad in 1954.