Baltimore and Ohio class S

S class S-1 and S-1a Class
B&O S-1a class #6206 in 1928
Type and origin Power type Steam Builder Baldwin Locomotive Works Lima Locomotive Works Build date 1914,1923–1926 Total produced 31 (Class S) 75 (Class S-1) 50 (Class S-1a) Rebuilder B&O Rebuild date 1925 Number rebuilt 2 (6009 and 6030)
Specifications Configuration: ​  • Whyte 2-10-2 Gauge 4 ft 8+1⁄2 in (1,435 mm) standard gauge Driver dia. 58 in:1473 mm(S class) 64 in:1626 mm(S-1 class) Wheelbase: ​  • Engine 436.510 Ib(198.0 t : S-1 class) (184.16 : S Class)  • Drivers 347.230 Ib(157.5 t S-1 class) (152.77 t : S class) Boiler: ​  • Diameter 90 in to 100 in (2286 mm to 2540 mm : S-1 class) Boiler pressure 220 Ib:15.5 kg/cm2(S-1 class) 200 Ib:14.1 kg/cm2(S Class ) Heating surface: ​  • Firebox 262 sq.ft(S-1 class)  • Tubes 4881 sp.ft(140.5 m2 : S-1 class)  • Total surface 5270 sq.ft(489.6 m2 : S-1 class) (517.8 m2 : S class) Superheater: ​  • Heating area 1512 sq.in(140.5 m2 : S-1 class) (123.5 m2 : S class) Cylinder size 30 in x 32 in (762 mm x 813 mm : S-1 class) 30 in x 32 in (762 mm x 813 mm : S class)
Performance figures Maximum speed 55-75 Mph
Career Operators Baltimore and Ohio Railroad Class S,S-1 and S-1a Number in class 31 (S class) 125 (S-1) Numbers 6000–6030 (S class) 6100-6224 (S-1 Class) Nicknames "big sixes" Locale Eastern United States Retired 1926 (2) 1938 (15) 1953-1959 (Remainder) Preserved 0 Scrapped 1926,1938,1953-1959 Disposition All Scrapped by 1959.

Baltimore and Ohio Class S comprised three classes of 2-10-2 locomotives.

The S class proper were 31 locomotives built in 1914 by Baldwin Locomotive Works and numbered 6000–6030. The S-1 class comprised 50 locomotives numbered 6100–6149, and 25 locomotives numbered 6150-6174. They were built between 1923 and 1924, 75 by Baldwin and by Lima Locomotive Works . The Class S-1a were built in 1926. The first batch of 25 were built by Lima, and numbered 6175-6199. The second batch was built by Baldwin, and numbered 6200-6224.^[1] They were nicknamed "big sixes" because until renumbering in 1954 their road numbers all began with 6.^[1] Locomotives numbered 6009 and 6030 were scrapped in 1925, and their boilers used to build new Class T 4-8-2 Mountain Type locomotives numbered 5500 & 5501. 15 of the Class were retired and scrapped in 1938. The remainder of S-1/S-1a continued service until 1953-1959.

None of the B&O Class S 2-10-2s were preserved.