By the end of the 19th century the B&O had achieved almost 5,800 miles of track and connected Chicago and St. Louis to Baltimore, Washington, Philadelphia, and New York City. The B&O continued to grow and in 1927 acquired a 40 percent share in the Western Maryland Railway. The railroad celebrated its 100th anniversary in 1927.
The Baltimore & Ohio Railroad began to build its huge fleet of "Mikado" type locomotives in 1911. That year, the Baldwin Locomotive Works delivered 160 of them which the B&O designated as Class Q-1 and assigned them road numbers 4000 through 4159. The Class Q-1s had 64" diameter drivers, 24" x 32" cylinders, a 205 psi boiler pressure, they exerted 50,184 pounds of tractive effort and each weighed 276,050 pounds. The fire box area was 228 square feet. The first 150 were not superheated and had an evaporative surface of 5,017 square feet. The last ten were delivered with superheaters and were reclassified as Class Q-1a. Later the first 150 were superheated and the boiler pressure was reduced to 195 psi and the boiler pressure on the ten Class Q-1a locomotives was also reduced to 195 psi. These 160 Q-1 and Q-1a locomotives were reclassified as Class Q-1aa.
There were two other 2-8-2s added to the B&O roster in 1911. In its own shops the B&O took two of its Class E-27 2-8-0s and extended the boilers, increased the cylinder diameter from 22" to 24" and removed the 60" diameter drivers and replaced them with 62" drivers. The valve gear was changed and superheaters were added. They were designated as Class Q-odd and assigned road numbers 4160 and 4161. The locomotives were built with different frames probably as a test of two different designs. Number 4160 had a wheelbase of 35'-7" and 4161's wheelbase was 35'-3". The Class Q-odd locomotives had 62" diameter drivers, 24" x 30" cylinders, a 215 psi boiler pressure, they exerted 50,935 pounds of tractive effort and each weighed about 254,850 pounds.
In 1912, Baldwin built fifty more "Mikados" for the B&O. They were desinated as Class Q-1b and given road numbers 4170 though 4219. These locomotives were similar to those delivered in 1911 but they had 26" x 32 cylinders, a 190 psi boiler pressure, they exerted 54,587 pounds of tractive effort and they were superheated. Each weighed 276,000 pounds. The firebox was larger 256 square feet versus 236 square feet. The evaporative surface was 3,926 square feet and with the superheater it had a combined heating surface of 4,737 square feet.
During 1913, another 110 Baldwin-built 2-8-2s arrived. These locomotives were almost identical to the group delivered in 1912. This group was designated as Class Q-1c with road numbers 4220 through 4329 assigned. The Class Q-1c locomotives were delivered with 28 sq ft of arch tubes an improvement that would eventually be installed in many of the previously delivered "Mikados". These locomotives had 64" diameter drivers, 26" x 32" cylinders, a 190 psi boiler pressure, they exerted 54,587 pounds of tractive effort and each weighed 284,500 pounds.
In 1916, the B&O took delivery of fifty more Baldwin-built "Mikados". This group was assigned road numbers 4830 through 4879. The B&O controlled several other railroads and influenced their locomotive designs and classification as well as road numbers. Class Q-2 through Q-7e designations were already being use for 2-8-2s on these railroads so this group was designated as Class Q-7f. The Q-7f locomotives had 64" diameter drivers, 26" x 32" cylinders, a 190 psi boiler pressure, they exerted 54,587 pounds of tractive effort and each weighed 281,900 pounds. The firebox area was 260 square feet, the evaporative heating surface was 3,970 square feet and with the superheater the combined heating surface was 4,853 square feet. The tenders for these Class Q-7f locomotives were Vanderbilt tenders with a capacity of 10,000 gallons of water and 16 tons of coal.
In 1918, the B&O was allocated one hundred USRA light "Mikados" with 63" diameter drivers, which were fitted immediately with thicker tires to bring them up to the B&O 64" diameter standard, reducing the starting tractive effort to 53,868 pounds. They were designated as class Q-3 and were assigned road numbers 4500 through 4599.
In 1921, the first Class Q-4 "Mikado" type locomotives were delivered from Baldwin, the B&O's favorite builder, and by 1923 there were 135 of them on the roster. The driver diameter and the cylinder size, as well as the grate area were the same as the previously Baldwin built 2-8-2s, but the steam pressure was 220 psi, so the tractive effort was increased to 63,206 pounds. The boiler sizes of classes Q-1, Q-1b, Q-1c, Q-7f and Q-4 were about the same, but the Q4 had a slightly larger superheated
The Baltimore & Ohio always had interesting ideas about steam locomotive design. The Q4 was an excellent design, the combination of the high boiler pressure and small cylinder diameter lead to a locomotive, which was quite lively. On the other hand, it was not a terribly large boiler design. The inveterate tinkers at Baltimore came up with a plan to rebuild some, perhaps all, of the class to a 2-8-4, with a larger boiler, including a 54" combustion chamber. As was the case with so many bright ideas of the late 1920s and early 1930s, the Depression put an end to this concept.
During the early 1940s, the B&O built three of its "Mikados" into prototype high-speed freight engines with 70" diameter drivers and designated them as Class Q-4d. However, the stability with the two wheel leading truck was not considered adequate, so the rebuilding evolved into the very successful T3 class 4-8-2. The GN monsters, the product of a succession of rebuilding (and some new engines), had 69" diameter drivers. Whether this was done to permit higher train speeds or as a way to cut down on piston speeds and allow more room for adequate counterbalancing is unknown at this time.
There were other classes of 2-8-2s on the B&O, mostly acquired through mergers, but not in significant numbers. Many Class Q-1s were converted, to Pacifics and, later to 70" diameter driver 4-8-2s, class T3.
All of the Class Q-4, Q-4a and Q-4b were equipped with steam boiler for steam heat so they could be used in passenger service and during World War II they were used to pull troop trains. Also the B&O was one of the many railroads that change the name the "Mikado" 2-8-2 locomotives to "MacArthur" type in a spirit of patriotism. However, many old timers on the B&O continued to call these locomotives "Mikes".
In 1927, eight of the CI&W 2-8-2 were put on the B&O roster after that railroad was acquired. When the BR&P was acquired in 1932 forty-eight more "Mikados" were put on the roster. The former CI&W locomotives were given road numbers 4162 through 4169 and the former BR&P locomotives were assigned road numbers 4700 through 4747.
There is one surviving B&O 2-8-2 locomotive and it is numbers 4500, one of the USRA "Mikado-light" locomotives allocated in 1918. It is on display at the B&O Museum in Baltimore, MD.
The BR&P Railway took delivery of its first "Mikado" type locomotives in 1912. These seven 2-8-2s had 63" diameter drivers and were large enough to handle straight through freight service. The BR&P ordered another forty-one "Mikados" and took delivery of thirty-one during 1913 and 1914 and the last ten were put on the roster in 1917. ALCO's Brooks Locomotive Works in Dunkirk, New York built all of the B R& P's 2-8-2s. They were designated Class Z and assigned road numbers 400 through 447. In January 1931, the B&O took control of the BR&P and these locomotives were reclassified as Class Q-10 and given new road numbers 4700 through 4747. In January 1, 1932 the Baltimore & Ohio Railroad purchased the BR&P.
The Class Z locomotives had 63" diameter drivers, 26.5" x 30" cylinders, a 190 psi boiler pressure, they exerted 54,006 pounds of tractive effort and each weighed 275,000 pounds. The firebox area was 234 square feet. The evaporative heating surface was 3,625 square feet and with the superheater the combined heating surface was 4,375 square feet.
There are no surviving BR&P 2-8-2 "Mikado" type locomotives.
The Cincinnati, Indianapolis & Western Railroad was acquired by the B&O in 1927 and its locomotives were designated as Class Q-2 renumbered 4162 through 4169.
There are no surviving CI&W 2-8-2 "Mikado" type locomotives.
|Class||Qty.||Road Numbers||From Other RR||Year. Acquired||Year Built||Builder||Notes|
|Q-odd||2||4160 & 4161||1911||Baldwin||Numbers 4160 and 4161 scrapped in 1949.|
|Q-1||160||4000-4159||1911||Baldwin||Numbers 4000-4159 scrapped by 1955.|
|Q-1b||50||4170-4219||1912||Baldwin||Numbers 4170-4219 scrapped by 1955.|
|Q-1c||110||4220-4329||1913||Baldwin||Numbers 4220-4329 scrapped by 1941.|
|Q-7f||50||4830-4879||1916||Baldwin||Numbers 4830-4879 had Vanderbilt tenders. All Scrapped by 1959.|
|Q-3||100||4500-4599||1918||Baldwin||Numbers 4500-4599 USRA allocated "Mikado-Light" locomotives. All scrapped by 1959 except number 4500. Number 4500 survives and is on display the B&O Museum.|
|Q-4, a, b||100||4400-4499||1920-1922||Baldwin||Class Q-4 had three subclasses, Class Q-4 included numbers 4400-4444, Class Q-4a included numbers 4445-4449 and Class Q-4b included numbers 4450-4499. Numbers 4400-4499 scrapped by 1959.|
|Q-4 b||35||4600-4634||1923||Baldwin||Numbers 4600-4634 were heavy "Mikado" type (541,400 lbs.). All scrapped by 1951.|
|Q-2||8||4162-4169||CI&W||1927||1916||Lima||Numbers 4162-4169 acquired with the CI&W in 1927. Ex CI&W numbers 401-408, which the B&O renumbered 4162-4169. Numbers 4162-4149 scrapped in 1941.|
|Q-10||48||4700-4747||BR&P||1932||1912-1917||ALCO||Came with B&O ownership of the BR&P in 1932. Ex BR&P numbers 400-447. All scrapped by 1959.|
|Q-4d||3||4635-4637||1941-1942||B&O||Numbers 4635-4637 scrapped by 1955.|
|Z||7||400 - 406||1912||ALCO||Numbers 400-406 became B&O numbers 4700-4706 and reclassified as Class Q-10 in 1932. All scrapped by 1959.|
|Z||31||407 - 437||1913 - 1914||ALCO||Numbers 407-437 became B&O numbers 4707-4737 and reclassified as Class Q-10 in 1932. All scrapped by 1959.|
|Z||10||438 - 447||1917||ALCO||Numbers 438-447 became B&O numbers 4738-4747 and reclassified as Class Q-10 in 1932. All scrapped by 1959.|
January 35911-35924; February 36010-36030; March 36209-36213; April 36407-36410, 36418-36420, 36452-36455, 36494-36497; May 36528-36538, 36597-36613, 36619-36623, 36630-36633; June 36663-36668; July 36672-36681, 36686, 36692-36693, 36706-36710, 36728-36739; August 36777-36782, 36789-36794, 36836-36837; September 36841-36848. (10 Q-1a were superheated variants with the same cylinder volume.)
These were the first B & O Mikados, bought at the insistence of the new president Daniel Willard, who realized that the longer, heavier trains traveling over the Western Maryland mountains needed more power. The O-1s set the standard for most of the succeeding 2-8-2s that the railroad would buy. They were delivered as saturated engines using 14" (356 mm) piston valves for steam distribution and their boilers were virtually identical to those mounted on the B & O's first Pacifics (Locobase 2884).
Last Q-1 retired in 1956 (although the last Q-1a left service in 1941). Q-1b (4150-4219 - see Locobase 9613)) and Q-1c (4220-4319 - Locobase 9614) had 26" x 32" cylinders and a 190-psi working pressure.
Locobase needs to confirm that the two classes shared the same boiler -- a design economy pursued by the Pennsylvania with great success in its K-4 and L-1 designs of three years later. The information provided in the diagrams suggests, however, that the Q-1 was very short of direct heating surface.
Although the first 150 of the Q-1 locomotives had saturated boilers, Baldwin and the B&O soon switched to a superheated design that would serve as standard equipment for the road's 2-8-2s as well as its Pacifics. Adding 28 sq ft (2.6 sq m) of arch tubes to the firebox of the first 20 locomotives, beginning in 1916, fortified a rather anemic direct heating surface area and caused a change of designation to Q-1BA. Specifications for the 4170 and later included 32 sq ft (2.97 sq m) of arch tubes during their manufacture.
Hundreds of B & O Mikados and Pacifics were built or reworked to this common baseline, which included not only the firebox and boiler, but also the cylinders and 14" (356 mm) piston valves. Cylinder volume increased over earlier B&O Mikes thanks to a 2" (50.8 mm) increase in cylinder diameter. A Street overfeed mechanical stoker conveyed the coal to the firebox. The Q-1C, which is shown separately in Locobase 9614, was delivered with arch tubes in the firebox, but was otherwise identical.
As noted in Locobase 9613, the boiler, firebox, and cylinders of the superheated Q-1 Mikes appeared in virtually all of the B & O's pre-World War I Mikados and Pacifics or was retrofitted to those classes in the 1920s. The Q-1c class shown here was delivered with everything in place, including the 32.2 sq ft (3 sq m) in four arch tubes that all such locomotive would eventually use. 14" (356 mm) diameter piston valves were also typical. A Street overfeed mechanical stoker conveyed the coal to the firebox.
One clear difference between the Q-1B and Q-1C was the original superheater area in the specs. Even though the two subclasses had the same number of superheater elements of the same diameter (1 7/16"/36.5 mm), the Q-1B's superheater was credited with 998 sq ft (92.72 sq m), the Q-1C with 838 sq ft (77.85 sq m). Locobase is unable to determine the source of the difference; it could represent a choice between a superheater element's outside diameter (fire side) and its inside diameter (steam side).
Unlike many other railroads, however, the B & O didn't add other heat-augmenting devices like thermic syphons to these earlier engines. Every one of the Q-1cs served the B&O through World War II and most were retired only in the 1950s.
The variant shown in the specs had the larger of the two superheater installations. The other boiler had 218 2 1/4" small tubes and 34 5 1/2" flues; total EHS came to 3,962 sq ft and superheater surface area totalled 811 sq ft. Firebox heating surface for both versions was the same and included 26 sq ft of arch tubes. Many of these were later converted to Pacific passenger power as P-1c; see Locobase 9610.
The large class was obviously a common 2-8-2 type on the B & O and served until the end of steam.
One of the few Lima-built classes on the B&O, once the CI&W came under the bigger railroad's control. Renumbered in 1927 as 4162-4169 and ran until 1948-1949..
Works numbers were:
July 49153-49154, 49224-49225, 49288-49290, 49380-49388, 49395-49399; August 49457-49469, 49526-49539, 49614-49615; December 50809-50816, 50936-50938, 50986-50987
January 51030, 51075-51077, 51108-51115, 51142-51149, 51180; February 51224-51230, 51282, 51299-51302, 51376-51379
100 light Mikados delivered in 1918, beginning with the very first locomotive from a United States Railroad Administration (USRA) design. Compared to the earlier Q-1s, this class had more firebox heating surface than the earlier engines. Like the other USRA Light Mikados, these had 14" (356 mm) piston valves.
In Baldwin's specs for the first batch, supplemental note 23 highlights the meticulous examination of every factor likely to affect the success of this unprecedented standardization. As the 4500 and its 49 others were the first, "The Government desires these locos to be the most conveniently arranged machines ever handled by enginemen and firemen. For this purpose, we are to confer with the Government expert inspector to arrange the details."
Latter-day cynics are likely to read the above and reflect sourly with a shudder on words that sound suspiciously like "We're from the government and we're here to help you." Morever, it is certainly true that crews on different railroads had different views of what "most conveniently arranged" might mean.
But Locobase notes that it is also that the USRA designs for the most part earned enduring regard for the quality of their design and operation. He also supposes that the "expert" was a long-time railroad man as were the committtee members that laid out the fleet. Such an observer would likely be aware of preferences and traditions.
According to the ASME citation, the 4500 began the program auspiciously: "The 4500 was built in only 20 days, which is a record for any locomotive of similar capacity. This was the result of the wishes of Samuel M. Vauclain, then the Senior Vice President of Baldwin,
who wanted his company to have the honor of completing the first USRA engine. In accordance with his orders, the engine was finished on July 4, 1918, and was decked out with American flags for the occasion."
With that patriotic birthday wish met, ASME succinctly notes the 4500's career and reputation:
"The B&O classed the 4500 as a Q-3 Mikado freight locomotive, and as such it toiled in anonymity primarily on the Ohio and St.Louis divisions of the B&O for 39 years. During this time, the 100 Q-3 class engines gained a fine reputation among B&O enginemen as
free steaming, powerful, easy riding and comfortable engines."
Last Q-3 retired in 1959.
February 54543-54544, 54559
March 54566-54582, 54648, 54655-54659, 54675-54685
April 54709-54713, 54727
September 55636-55638, 55669-55680
October 55757-55768, 55774-55776
December 55869-55873, 55897-55902
January 55997-56007, 56100-56110
A note in the specs says that the "cylinder is specified 26" diameter, which is the nominal diameter. Cylinders bored 25 3/4" diameter are to be applied to locomotives." The note continued with an explanation: "Cylinders to be of entirely new design, to suit double rail construction and having all walls and ribs of thickness shown on Ry, Co's prints." Further details available at supplemental paragraphs 352 et seq (Spec page 235).
Among the precise specs for all components is this more general note: "Special attention called to the heavier rods, axles, etc. on locomotives, which are required by the 60,000 pounds tractive power obtained by a 26" x 32" cylinder and 210 working pressure." (Note: the last 85 engine boiler pressures were set at 220 psi.)
Firebox heating surface included 28 sq ft (2.6 sq m) of arch tubes in the Q-4, 34 sq ft (3.15 sq m) in the Q-4b as delivered. Later variations included a semi-water tube firebox in which 29 sq ft (2.7 sq m) of arch tubes added their area to the sheets, troughs, and side tubes of the water-tube box. Others added a tiny combustion chamber that contributed only 6 sq ft (0.56 sq m). When three arch tubes were deducted (leaving 14 sq ft/1.3 sq m) and 70 sq ft (6.5 sq m) of thermic syphons were added, the total firebox heating surface came to 309 sq ft (28.7 sq m).
Valve gear varied. All but five came with Baker-Pilliod gear, which showed a 7" (178 mm) travel, 1/4" (6.25 mm) lead , and a 1" (25.4 mm) lap. The quintet numbered 4445-4449 were specified for Young valve gear., which had a maximum travel of 9" (229 mm), 1 3/8" (35 mm) lap, and 5/16" (7.9 mm) lead. These appear in later B&O diagrams as having "Improved Walschaert" gear. Piston valves measured 14" (356 mm) in diameter.
As delivered, the class trailed tenders carrying 12,000 US gallons (45,420 litres) of water and 20 tons (18,144 kg) of coal; loaded weight was 213,600 lb (96,888 kg). As Locobase's specs show, the B&O later rebalanced the water/fuel ratio most likely to eliminate some stops for one or the other component.
135 engines delivered in 1920-1923. May have shared components with better-known Big Six 2-10-2. These locomotives were rated for passenger service.
Last Q-4 retired in 1959.
August 43867-43872, 43934-43937, 43948-43949, 43967-43971; September 44091-44094, 44162-44166; October 44187-44196, 44249-44252, 44302, 44395-44398; November 44407-44408; December 44557-44589
Originally to have been numbered 4330-4380, this class was renumbered before delivery. These had the cylindrical Vanderbilt tenders. Firebox heating surface included 31.5 sq ft (2.9 sq m) in four arch tubes. Piston valves measured 14" (356 mm) in diameter. Fitted with Street automatic stokers.
Probably as an experiment, the B & O took two of its numerous E-27 class of 2-8-0s (Locobase 2885) and converted them into these superheated Mikados. Given that the boiler was lengthened, the driver and cylinder diameters increased, valve gear changes, superheater added -- about the only component retained was the relatively small firebox.
Another sign of experimentation was the slightly different rear frame lengths of the two engines. 4160's engine length was as shown in the specs; 4161's measured 35 ft 3 in. In any case, this eight-coupled Odd Couple operated in freight service until 1949.
The only BR&P Mikados, this set had the same boiler and firebox as the Pacifics produced by the same builder in the same year (Locobase 2063). Fourteen inch (356 mm) piston valves supplied steam to the cylinders.
The class was broken into 4 subclasses by the B&O in 1932 and renumbered 4700-4747. Q-10 (400-406), Q-10a (407-437), Q-10b 438-446), and Q-10c (447). These basic freight engines soldiered on until the end of steam in 1954.
|Specifications by Steve Llanso of Sweat House Media|
|Class||Q-1||Q-1B / Q-1B||Q-1C||Q-1aa||Q-2|
|Railroad||Baltimore & Ohio (B&O)||Baltimore & Ohio (B&O)||Baltimore & Ohio (B&O)||Baltimore & Ohio (B&O)||Cincinnati, Indianapolis, & Western (B & O)|
|Number in Class||140||70||110||140||8|
|Road Numbers||4000-4139||4150-4219||4220-4329||4000-4139||401-408 / 4162-4169|
|Locomotive Length and Weight|
|Driver Wheelbase (ft / m)||16.75 / 5.11||16.75 / 5.11||16.75 / 5.11||16.75 / 5.11||16.50 / 5.03|
|Engine Wheelbase (ft / m)||35 / 10.67||35 / 10.67||35 / 10.67||35 / 10.67||35.17 / 10.72|
|Ratio of driving wheelbase to overall engine wheebase||0.48||0.48||0.48||0.48||0.47|
|Overall Wheelbase (engine & tender) (ft / m)||71.21 / 21.70||71.21 / 21.70||71.21 / 21.70||71.84 / 21.90||66.56 / 20.29|
|Axle Loading (Maximum Weight per Axle) (lbs / kg)||55,240 / 25,056||56,400 / 25,583||56,200 / 25,492||56,450 / 25,605|
|Weight on Drivers (lbs / kg)||218,740 / 99,219||223,600 / 101,423||222,000 / 100,698||223,600 / 101,423||220,100 / 99,836|
|Engine Weight (lbs / kg)||276,050 / 125,214||282,200 / 128,004||284,500 / 129,047||282,200 / 128,004||294,500 / 133,583|
|Tender Loaded Weight (lbs / kg)||151,000 / 68,493||181,500 / 82,327||180,000 / 81,647||181,500 / 82,327||177,000 / 80,286|
|Total Engine and Tender Weight (lbs / kg)||427,050 / 193,707||463,700 / 210,331||464,500 / 210,694||463,700 / 210,331||471,500 / 213,869|
|Tender Water Capacity (gals / ML)||9500 / 35.98||9500 / 35.98||9500 / 35.98||9500 / 35.98||9000 / 34.09|
|Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)||10.50 / 9.50||18.50 / 16.80||18.50 / 16.80||18.50 / 16.80||12 / 10.90|
|Minimum weight of rail (calculated) (lb/yd)||91||93||93||93||92|
|Geometry Relating to Tractive Effort|
|Driver Diameter (in / mm)||64 / 1626||64 / 1626||64 / 1626||64 / 1626||63 / 1600|
|Boiler Pressure (psi / kPa)||205 / 14.10||190 / 13.10||190 / 13.10||190 / 13.10||185 / 12.80|
|High Pressure Cylinders (dia x stroke) (in / mm)||24" x 32" / 610x813||26" x 32" / 660x813||26" x 32" / 660x813||26" x 32" / 660x813||27" x 30" / 686x762|
|Tractive Effort (lbs / kg)||50,184 / 22763.11||54,587 / 24760.28||54,587 / 24760.28||54,587 / 24760.28||54,588 / 24760.73|
|Factor of Adhesion (Weight on Drivers/Tractive Effort)||4.36||4.10||4.07||4.10||4.03|
|Firebox Area (sq ft / m2)||228 / 21.19||260 / 23.79||260.20 / 24.17||254 / 23.61||238 / 22.12|
|Grate Area (sq ft / m2)||70 / 6.51||70 / 6.51||70 / 6.50||70 / 6.51||70 / 6.51|
|Evaporative Heating Surface (sq ft / m2)||5017 / 466.26||3926 / 364.87||3926 / 364.73||3918 / 364.13||4236 / 393.68|
|Superheating Surface (sq ft / m2)||811 / 75.37||811 / 75.34||988 / 91.82||946 / 87.92|
|Combined Heating Surface (sq ft / m2)||5017 / 466.26||4737 / 440.24||4737 / 440.07||4906 / 455.95||5182 / 481.60|
|Evaporative Heating Surface/Cylinder Volume||299.43||199.65||199.65||199.25||213.07|
|Computations Relating to Power Output (More Information)|
|Robert LeMassena's Power Computation||14,350||13,300||13,300||13,300||12,950|
|Same as above plus superheater percentage||14,350||15,561||15,561||15,960||15,281|
|Same as above but substitute firebox area for grate area||46,740||57,798||57,842||57,912||51,955|
|Specifications by Steve Llanso of Sweat House Media|
|Class||Q-3||Q-4||Q-7-f||QoddA||Z / Q-10|
|Railroad||Baltimore & Ohio (B&O)||Baltimore & Ohio (B&O)||Baltimore & Ohio (B&O)||Baltimore & Ohio (B&O)||Buffalo, Rochester, & Pittsburgh (B&O)|
|Number in Class||100||135||50||2||48|
|Road Numbers||4500-4599||4400-4499, 4600-4634||4830-4879||4160-4161||400-447|
|Builder||Baldwin||Baldwin||Baldwin||B & O||Brooks|
|Locomotive Length and Weight|
|Driver Wheelbase (ft / m)||16.75 / 5.11||16.75 / 5.11||16.75 / 5.11||16.67 / 5.08||16.50 / 5.03|
|Engine Wheelbase (ft / m)||36.08 / 11||35.09 / 10.70||35 / 10.67||35.58 / 10.84||34.75 / 10.59|
|Ratio of driving wheelbase to overall engine wheebase||0.46||0.48||0.48||0.47||0.47|
|Overall Wheelbase (engine & tender) (ft / m)||41.98 / 12.80||74.23 / 22.63||72 / 21.95||65.39 / 19.93||71.94 / 21.93|
|Axle Loading (Maximum Weight per Axle) (lbs / kg)||55,200 / 25,038||62,800 / 28,486||56,680 / 25,710|
|Weight on Drivers (lbs / kg)||220,000 / 99,790||247,000 / 112,037||222,100 / 100,743||206,710 / 93,762||217,500 / 98,656|
|Engine Weight (lbs / kg)||292,000 / 132,449||327,400 / 148,506||281,900 / 127,868||256,360 / 116,283||275,000 / 124,738|
|Tender Loaded Weight (lbs / kg)||185,400 / 84,096||219,000 / 99,337||181,100 / 82,146||148,070 / 67,164||202,700 / 91,943|
|Total Engine and Tender Weight (lbs / kg)||477,400 / 216,545||546,400 / 247,843||463,000 / 210,014||404,430 / 183,447||477,700 / 216,681|
|Tender Water Capacity (gals / ML)||10,000 / 37.88||18,000 / 68.18||10,000 / 37.88||7000 / 26.52||12,000 / 45.45|
|Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)||16 / 14.50||17.50 / 15.90||16 / 14.50||18 / 16.40||14 / 12.70|
|Minimum weight of rail (calculated) (lb/yd)||92||103||93||86||91|
|Geometry Relating to Tractive Effort|
|Driver Diameter (in / mm)||64 / 1626||64 / 1626||64 / 1626||62 / 1575||63 / 1600|
|Boiler Pressure (psi / kPa)||200 / 13.80||220 / 15.20||190 / 13.10||215 / 14.80||190 / 13.10|
|High Pressure Cylinders (dia x stroke) (in / mm)||26" x 30" / 660x762||25.75" x 32" / 660x813||26" x 32" / 660x813||24" x 30" / 610x762||26.5" x 30" / 673x762|
|Tractive Effort (lbs / kg)||53,869 / 24434.60||61,996 / 28120.95||54,587 / 24760.28||50,934 / 23103.30||54,006 / 24496.74|
|Factor of Adhesion (Weight on Drivers/Tractive Effort)||4.08||3.98||4.07||4.06||4.03|
|Firebox Area (sq ft / m2)||286 / 26.57||263 / 24.44||260 / 24.15||179.20 / 16.65||234 / 21.75|
|Grate Area (sq ft / m2)||66.70 / 6.20||70 / 6.51||70 / 6.50||56.24 / 5.23||56 / 5.20|
|Evaporative Heating Surface (sq ft / m2)||3777 / 350.89||3813 / 354.37||3970 / 368.82||3052 / 283.64||3625 / 336.90|
|Superheating Surface (sq ft / m2)||882 / 81.94||955 / 88.75||882 / 81.94||601 / 55.86||750 / 69.70|
|Combined Heating Surface (sq ft / m2)||4659 / 432.83||4768 / 443.12||4852 / 450.76||3653 / 339.50||4375 / 406.60|
|Evaporative Heating Surface/Cylinder Volume||204.88||197.69||201.89||194.30||189.29|
|Computations Relating to Power Output (More Information)|
|Robert LeMassena's Power Computation||13,340||15,400||13,300||12,092||10,640|
|Same as above plus superheater percentage||15,875||18,480||15,694||14,026||12,449|
|Same as above but substitute firebox area for grate area||68,068||69,432||58,292||44,692||52,018|