Atlanta, Birmingham & Atlantic 2-8-2 "Mikado" Locomotives in the USA

The Atlanta, Birmingham & Atlantic Railway was reorganized in 1926 and renamed the Atlanta, Birmingham & Coast Railroad. It was controlled by the Atlantic Coast Line which had acquired a majority of its stock. Its 287 mile main line ran from Birmingham, AL to Brunswick, GA, with a 33 mile branch from Manchester, GA to Atlanta, GA, an 80 mile branch from Fitzgerald, GA to Thomasville, GA and a 26 mile branch from Sessoms, GA to Waycross, GA.

Two decades later, in 1946, ACL purchased the company entirely and absorbed it into its own operations as the Atlantic Coast Line western division.

The Atlanta, Birmingham & Atlantic Railway bought two "Mikado" type locomotives in 1910 from the Baldwin Locomotive Works. They were assigned road numbers 71 and 72 which were later changed to 90 and 91 and then to 301 and 302 on the Atlanta, Birmingham & Coast. These locomotives had 57" diameter drivers, 24" x 32", a 200 psi boiler pressure, they exerted 62,059 pounds of tractive effort and each weighed 266,100 pounds. The firebox was 210.3 square feet, the evaporative heating surface was 3,686 square feet and with the superheater the combined heating surface was 4,540 square feet.

Fifteen more "Mikados" were added to the roster late 1912 and 1913. They were built by Baldwin and were assigned road numbers 92 through 106 and later on the AB&C they carried road numbers 201 through 215. These locomotives had 57" diameter drivers, 24" x 30", a 185 psi boiler pressure, they exerted 47,072 pounds of tractive effort and each weighed 249,900 pounds. The firebox was 210 square feet, the evaporative heating surface was 3,156 square feet and with the superheater the combined heating surface was 3,819 square feet.

During the period from 1938 through 1941 the AB&C acquired eleven second-hand "Mikados" from the New York Central. These locomotives were given road numbers 225 through 236.

There are no surviving AB&C 2-8-2 "Mikado" type locomotives.


Roster by Richard Duley

ClassQty.Road NumbersFrom Other RRYear AcquiredYear BuiltBuilderNotes
K-215201-2151912-1913Baldwin1
K-3 2301-3021910Baldwin2
K 2225-226CCC&StL19381915ALCO3
K 1227NYC&HR19381915ALCO3
K 1228CCC&StL19381914ALCO3
K 1229CCC&StL19381913ALCO3
K 1230CCC&StL19381915ALCO3
K 1231CCC&StL19381912ALCO3
K 2232-233NYC&HR19381912ALCO3
K 1234NYC&HR19411913ALCO3
K 1235NYC&HR19411912ALCO3
Notes:
  1. Numbers 201, 202, 203, 206, 207 and 210 sold to the Missouri & Arkansas. Numbers 211 and 215 sold to Chehalis & Western. Numbers 204, 212 and 214 scrapped prior to 1946. Numbers 205, 208, 209 and 213 conveyed to the Atlantic Coast Line and renumbered as ACL numbers 7205, 7208, 7209 and 7213. Numbers 7205, 7208, 7209 and 7213 scrapped in 1951.
  2. Numbers 301 and 302 conveyed to the ACL in 1946 and renumbered as ACL numbers 7301 and 7302. Numbers 7301 and 7302 scrapped in 1947.
  3. Numbers 225-235 came from the NYC between 1938 and 1941.
    225 and 226 were CCC&StL numbers 6055 and 6056 bought in 1938
    227 was NYC&HR 3856 bought in 1938
    228 was CCC&StL 6035 bought in 1939
    229 was CCC&StL 6715 bought in 1939
    230 was CCC&StL 6061 bought in 1939
    231 was CCC&StL 6148 bought in 1939
    232 was NYC&HR 3611 bought in 1939
    233 was NYC&HR 3718 bought in 1939
    234 was NYC&HR 3774 bought in 1941
    235 was NYC&HR 3693 bought in 1941
    All conveyed to the ACL in 1946 and renumbered as ACL numbers 7225-7235. Numbers 7225-7235 scrapped in 1952.

Class Details by Steve Llanso of Sweat House Media

Class K-2 (Locobase 7859)

Data from AB&C 11-1930 Locomotive Diagrams and Passenger Car Data book supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange. See also DeGolyer, Volume 43, pp. 83+ and Volume 50, pp. 67+; and "Mikado Type Locomotives for Atlanta, Birmingham & Atlantic", Railway and Locomotive Engineering, Volume 26, No 3 (March 1913), p. 93. See Works numbers were 38933-38937 in December 1912, 40302-40306 in August 1913, 41739-41743 in October 1914.

These relatively small Mikados came to the AB&C in three batches and were taken into the Atlantic Coast Line as their AK-2. Locobase cannot determine if the 35.7 sq ft (3.32 sq m) of arch tubes is included in the 210 sq ft of firebox heating surface given in both the Baldwin specs and in several AB&C diagram books.

The specs note that four arch tubes will hold the fire brick arch and it was to work "in combination with the Gaines combustion chamber." The combustion chamber consisted of an extension of the firebox that was demarcated by a half-height vertical wall. (Other engines with similar setups are described as having a Gaines wall in the firebox.) Thus, the R&LE report noted, a grate that measured 134" (3.404 m) was actually divided into an 89" (2,261m) long grate and a combustion chamber.

Other features included relatively generous 13" (331 mm) piston valves.

Serving the ACL until 1947-1952, many were then sold to short lines and industrial railroads.


Class K-3 (Locobase 13544)

Data from Baldwin Locomotive Works Specification for Engines as digitized by the DeGolyer Library of Southern Methodist University, Volume 34, p. 157. See also "Mikado Locomotive for the Atlanta, Birmingham & Atlantic", Railway Age Gazette, Volume 49, No 7 (12 August 1910), pp. 282-283. Works numbers were 34717-34718 in May 1910.

Surprisingly small grate and firebox on this Mikado, or is the boiler simply huge? That was the question Locobase first posed years before he found the RAG article shown in the first paragraph. That report wondered as well at the disproportion of heating surface to grate:

"The ratio of grate area to heating surface is as 1 to 91.7, which is very much greater than the most liberal practice of a few years ago. in this connection the evaporative work of engines with this large ratio will be of interest and value."

RAG's report referred to the Maintenance of Way Association's Economics of Railway Location Committee's conclusion that a 50:1 ratio produced the highest rate of evaporation. 50:1 owed some of its merit to physical constraints in earlier decades, especially in practical grate area. Still, said RAG, a ratio of nearly double raised the question of "whether the additional steam production corresponds with the added cost and at what point this increase of ratio will cease to be profitable."

RAG also pronounced the relatively low 170 psi boiler pressure was "a matter of interest. It corresponds very closely with Prof. Goss's point of maximum efliciency, and it would be of great value if this matter could be tested to a finish."

In assessing the design, Locobase finds the combination of outside Baker valve gear and slide valves "interesting" as well. Valve travel of 5 5/8" (143 mm) seems short, but the relatively low drivers may have dictated that setting to some extent.

Locobase 7860 shows the 1916 superheated upgrade.


Class K-3 - superheated (Locobase 7860)

Data from AB&C 6-1928, 6-1942, and 1-1943 Locomotive Diagrams and Passenger Car Data book supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange.

Locobase finds it very hard to believe that superheating the Mikados shown in Locobase 13544 would also result in a grate area as small as 43.3 sq ft, yet all of the AB&C diagram books insisted on that figure. This represented a 15.2 sq ft decrease from the original grate in the bloated saturated boilers originally delivered with these engines in 1910. In the same makover, 210 of the 2 1/4" tubes were removed in favor of 40 flues.

(NB: All of the diagram books prior to 1943 show much higher evaporative heating surface areas. Locobase believes that the figure given included the superheater area, which is also shown separately. The math was corrected in the 1943 edition, which is the source of Locobase's specifications.)

The diagrams suggest that a combustion chamber in the boiler, but there's no clear indication of such. Also the firebox had four arch tubes, which would have added about 28 sq ft to the direct heating surface. But the ratios were still very high and the factor of adhesion quite low, despite the addition of 10,000 lb (4,535 kg) of "dead weight" to the drivers in October 1939 (3020 and April 1940 (301).

The diagrams note that a May 1925 shop stop saw the installation of a feedwater heater and a mechanical lubricator in 302; 301 received a similar upgrade in December. The 1929 makeover added a "Hylastic" steel frame, new piston valves and cylinders, ACL standard binders, and improved Baker valve gear. Automatic stokers were added in 1940.

After the ACL took over the AB & C in December 1945, these two were redesignated AK-3. 301 suffered a wreck in June 1946 and was scrapped. 302 went to the scrapper in April 1947.

Specifications by Steve Llanso of Sweat House Media
ClassK-2K-3K-3 - superheated
Locobase ID7859 13,544 7860
RailroadAtlanta, Birmingham & Atlantic (AB&C)Atlanta, Birmingham & Atlantic (AB&C)Atlanta, Birmingham & Atlantic (AB&C)
CountryUSAUSAUSA
Whyte2-8-22-8-22-8-2
Number in Class1522
Road Numbers92-106/201-21571-72/90-9190-91/301-302/7301-7302
GaugeStdStdStd
Number Built152
BuilderBaldwinBaldwinAB&A
Year191219101916
Valve GearBakerBakerBaker
Locomotive Length and Weight
Driver Wheelbase (ft / m)15 / 4.5716 / 4.8816 / 4.88
Engine Wheelbase (ft / m)32.33 / 9.8531.50 / 9.6033 / 10.06
Ratio of driving wheelbase to overall engine wheebase 0.46 0.51 0.48
Overall Wheelbase (engine & tender) (ft / m)65.07 / 19.8362 / 18.9064.27 / 19.59
Axle Loading (Maximum Weight per Axle) (lbs / kg)46,750 / 21,20550,200 / 22,770
Weight on Drivers (lbs / kg)187,000 / 84,822200,000 / 90,719209,000 / 94,801
Engine Weight (lbs / kg)249,900 / 113,353260,000 / 117,934283,400 / 128,548
Tender Loaded Weight (lbs / kg)142,000 / 64,410135,000 / 61,235175,300 / 79,515
Total Engine and Tender Weight (lbs / kg)391,900 / 177,763395,000 / 179,169458,700 / 208,063
Tender Water Capacity (gals / ML)7500 / 28.417000 / 26.528400 / 31.82
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)12 / 10.9014 / 12.701712 / 6.50
Minimum weight of rail (calculated) (lb/yd)788387
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)57 / 144857 / 144857 / 1448
Boiler Pressure (psi / kPa)185 / 12.80170 / 11.70200 / 13.80
High Pressure Cylinders (dia x stroke) (in / mm)24" x 30" / 610x76225" x 32" / 635x81325.5" x 32" / 648x813
Tractive Effort (lbs / kg)47,672 / 21623.6850,702 / 22998.0762,059 / 28149.52
Factor of Adhesion (Weight on Drivers/Tractive Effort) 3.92 3.94 3.37
Heating Ability
Firebox Area (sq ft / m2)210 / 19.52206 / 19.14210.30 / 19.54
Grate Area (sq ft / m2)51.90 / 4.8258.50 / 5.4343.30 / 4.02
Evaporative Heating Surface (sq ft / m2)3156 / 293.315365 / 498.423686 / 342.44
Superheating Surface (sq ft / m2)663 / 61.62854 / 79.34
Combined Heating Surface (sq ft / m2)3819 / 354.935365 / 498.424540 / 421.78
Evaporative Heating Surface/Cylinder Volume200.92295.10194.87
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation960299458660
Same as above plus superheater percentage11,234994510,305
Same as above but substitute firebox area for grate area45,45535,02050,051
Power L111,382568112,479
Power MT536.75250.49526.53

Photos

Reference