Baltimore & Ohio Mountains

In 1925, the Baltimore & Ohio Railroad built its first "Mountain" locomotive (road number 5500) using the boiler from number 6009, a Baldwin built Class S 2-10-2. A year later. the B&O built another (road number 5501) using the boiler from number 6030. These two locomotives were designated Class T and had 30 x 30 cylinders, 74" drivers, and a 220 psi boiler pressure which resulted in a tractive effort of 68,200 pounds. They weighed 400,000 lbs and worked on the west end of the Cumberland Division pulling passenger trains until retired in 1953.

In 1930, George Emerson, the General Superintendent of Motive Power & Equipment wanted to prove his theory that a water-tube firebox was practical. He had the B&O order two "Mountain" type locomotives from the Baldwin Locomotive Works, one (Class T-1, road number 5510) equipped with a water-tube firebox and the other (Class T-2, road number 5550) with a conventional type firebox. These two locomotives were identical except for their fireboxes and had 27.5 x 30 cylinders, 74" drivers, a 250 lbs boiler pressure and exerted 65,000 lbs of tractive effort. Number 5510 weighed 384,000 lbs and number 5550 weighed 1,000 lbs more. Emerson wanted to operate the two locomotives in similar service and then compare operating and maintenance costs. This experiment was never completed and the two "Mountains" were used until the early 1950s.

In the early 1940s, the B&O decided to build "Mountain" type locomotives to help with the increase in traffic caused by the war effort. From 1942 to 1948 it built forty of them (Class T-3, road numbers 5555 through 5594) in its Mt. Clare Shops in Baltimore, MD. These locomotives were built to the same general specifications which included 27 x 32 cylinders, 70" drivers, a boiler pressure of 230 psi, a tractive effort of 65,100 lbs and a weight of 375,000 pounds. There were some variations in the features of these locomotives as shown in the chart below. The Class T-3s were retired in 1960.

The B&O bought thirteen 4-8-2s from the Boston & Maine. They were given road numbers 5650 through 5662 and were designated as Class T-4 and were used until 1958.

There are no surviving B&O "Mountains". The Class Ts (numbers 5500 & 5501) were scrapped in 1953. Class T-1 number 5510 was scrapped in 1951 and Class T-2 number 5550 was scrapped in 1952. Some of the Class T-3s and T-4s were scrapped in the early 1950s. In 1957, all of the remaining T-3s and T-4s were renumbered in the 700 series. The T-4s were retired in 1958 and the T-3s lasted a little longer, but by 1960 all of the B&O "Mountain" had been scrapped.

Class	Qty.	Road Numbers	Year Built	Notes

T-3	3	5555-5557	1942	Vanderbilt tenders with 15,000 gallons of water and 26 tons of coal.
T-3	6	5558-5563	1943

T-3a	1	5564	1943	Same as T-3 except it had roller bearings on all axles.

T-3b	3	5565-5567	1943	Same as T-3 except it had large square tank tender with 20,000 gallons of water and 25 tons of coal. (no roller bearings)
T-3b	7	5568-5574	1944
T-3b	7	5575-5581	1945
T-3b	3	5582-5584	1946

T-3c	7	5585-5591	1947	Roller bearings on pony, tailing and tender axles. Same tender as T-3b.
T-3c	3	5592-5594	1948

Renumbering of Class T-3 and Class T-4 in 1957
Class T-3
5555	700
5556	scrapped
5557	701
5558	702
5559	scrapped
5560	scrapped
5561-5581	703-723
5582	scrapped
5583-5593	724-734
5594	scapped
Class T-4 (From B&M)
B&M Numbers	B&O Numbers	1957 Numbers
4100-4102	5650-5652	750-752
4103	5653	scrapped
4104	5654	753
4105-4106	5655-5656	scrapped
4107-4108	5657-5658	754-755
4109-4110	5659-5660	scrapped
4111-4112	5661-5662	756-757

Specifications
	Class T	Class T-1 & T-2
Wheel Arrangement:	4-8-2	4-8-2
Length:	100' - 6"	100' - 6"
Drivers:	74" dia.	74" dia.
Weight on Drivers:	275,000 lbs	260,000 lbs
Locomotive Weight:	400,000 lbs	384,000 lbs
Locomotive & Tender Weight:	659,300 lbs	657,000 lbs
Grate Area:	84.7 sq ft	92 sq ft
Cylinders (dia. x stroke):	(2)30" x 30"	(2) 27.5" x 30"
Boiler Pressure:	220 psi	250 psi
Tractive Effort:	68,200 lbs	65,000 lbs
Tender Capacity:	18,0000 gals. water, 20 tons coal	15,800 gals. water, 23 tons coal

Note: The tender for Class T-1 was the same as Class T.

	Classes T-3, T-3a, T-3b & T-3c	Class T-4
Wheel Arrangement:	4-8-2	4-8-2
Length:	101' - 6"	105' - 8"
Drivers:	70" dia.	73" dia.
Weight on Drivers:	255,000 lbs	269,300 lbs
Locomotive Weight:	375,000 lbs	416,000 lbs
Locomotive & Tender Weight:	740,000 lbs	788,800 lbs
Grate Area:	70 sq ft	79 sq ft
Cylinders (dia. x stroke):	27" x 32"	28" x 31"
Boiler Pressure:	230 psi	240 psi
Tractive Effort:	65,100 lbs	67,900 lbs
Tender Capacity:	15,000 gals. water, 26 tons coal	20,000 gals. water, 21 tons coal

Note: The tender for Class T-3b & T-3c had a capacity of 20,000 gals. of water and 25 tons of coal.

Baltimore & Ohio Mountains

Photos

References