Baltimore & Ohio Mikados

Between 1911 and 1916, the Baltimore & Ohio installed 372 "Mikados", designated as classes Q1, Q-1b, Q-1c and Q-7f. In 1918, the B&O was allocated 100 USRA light "Mikados" with 63" drivers, which were fitted immediately with thicker tires to bring them up to the B&O 64" standard, reducing the starting tractive effort to 53,800 pounds. They were designated as class Q-3.

In 1921, the first Class Q-4 "Mikado" type locomotives were delivered from Baldwin, the B&O's favorite builder. 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 starting tractive effort was increased to 63,200 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 superheater.

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 tinkerers 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" 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" 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" drivered class T3 4-8-2s.

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. 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".

There is one surviving B&O 2-8-2 locomotive. It is numbered 4500, one of the USRA "Mikado-light" locomotives that were allocated in 1918. It is on display at the B&O Museum in Baltimore, MD.

Class	Qty.	Road Numbers	Year Built	Builder	Notes
Q-odd	2	4160 & 4161	1911	Baldwin
Q-1	160	4000-4159	1911	Baldwin
Q-1b	50	4170-4219	1912	Baldwin
Q-1c	110	4220-4329	1913	Baldwin
Q-2	8	4162-4169	1916	Lima	Came from CI&W
Q-3	100	4500-4599	1918	Baldwin	USRA "Mikado-Light" locomotives
Q-4, a, b	100	4400-4499	1920-1922	Baldwin	Heavy Mikado type (541,400 lbs.), 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 and numbers 4600-4634.
Q-4b	35	4600-4634	1923	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 and numbers 4600-4634.
Q-4d	3	4635-4637	1941-1942	B&O
Q-7f	50	4830-4879	1916	Baldwin	Had Vanderbilt tenders
Q-10	48	4700-4747	1912-1917	ALCO	Came with B&O ownership of the BR&P in 1932 (Ex BR&P Class Z numbers 400-447)

Specifications
Class	Q-odd	Q-1	Q-1b	Q-1c	Q-3	Q-4	Q-4d	Q-7f
Wheel Arrangement:	2-8-2	2-8-2	2-8-2	2-8-2	2-8-2	2-8-2	2-8-2	2-8-2
Length:
Drivers:	60" dia.	64" dia.	64" dia.	64" dia.	64" dia.*	64" dia.	70" dia.	64" dia.
Weight on Drivers:			234,000 lbs.		221,500 lbs.
Total Locomotive Weight:	254,850 lbs.	276,050 lbs.	282,200 lbs.	284,500 lbs.	290,800 lbs.	541,400 lbs.	347,300 lbs.	281,900 lbs.
Locomotive & Tender Weight:
Grate Area:			70.0 sq. ft.	70.0 sq. ft.	66.7 sq. ft	70.0 sq. ft.
Cylinders (dia. x stroke):	(2) 22" x 30"	(2) 24" x 32"	(2) 26" x 32"	(2) 26" x 32"	(2) 26" x 30"	(2) 26" x 32"	(2) 27" x 32"	(2) 26" x 32"
Boiler Pressure:	205 psi	205 psi	190 psi	190 psi	200 psi	220 psi	230 psi	190 psi
Tractive Effort:	42,168 lbs.	50,184 lbs.	54,600 lbs.	54,600 lbs.	53,800 lbs.	63,200 lbs	65,500 lbs.	54,600 lbs.
Tender Capacity:
Coal:
Water:

* The B&O added larger tires to these USRA allocated "Mikado-Light" locomotives immediately after they arrived, which reduced the tractive effort by 800 pounds.
Note: Class Q-2 designated the 2-8-2s of the Cincinnati, Indianapolis & Western Railroad. Classes Q-5, Q-5a, Q-6 and Q-7 designated the 2-8-2s of the Alton Railroad (former Chicago & Alton Railroad).

Baltimore & Ohio Mikados

Photos

Reference