View source for Baltimore and Ohio class S

{{unreferenced|date=October 2024}}
{{Infobox locomotive
| name = S class S-1 and S-1a Class
| image = Baltimore & Ohio 2-10-2 freight locomotive, 6206 (CJ Allen, Steel Highway, 1928).jpg
| alt = 
| caption = B&O S-1a class #6206 in 1928
| powertype = Steam
| designer = 
| builder = [[Baldwin Locomotive Works]]<br>[[Lima Locomotive Works]]
| ordernumber = 
| serialnumber = 
| buildmodel = 
| builddate = 1914,1923–1926
| totalproduction = 31 (Class S) 75 (Class S-1) 50 (Class S-1a)
| rebuilder = B&O
| rebuilddate = 1925
| numberrebuilt = 2 (6009 and 6030)
| whytetype = [[2-10-2]]
| uicclass = 
| driver = <!-- e.g. 1st, 2nd  or 3rd coupled axle -->
| gauge = {{track gauge|ussg|allk=on}}
| leadingdiameter = 
| driverdiameter = 58 in:1473 mm(S class) 64 in:1626 mm(S-1 class)
| trailingdiameter = 
| tenderdiameter = <!-- tender wheel diameter -->
| minimumcurve = 
| wheelbase = 
| engine total = 436.510 Ib(198.0 t : S-1 class) (184.16 :  S Class)
| leading = 
| drivers = 347.230 Ib(157.5 t S-1 class) (152.77 t : S class)
| trailing = 
| tender total = 
| tendertruck = 
| wheelspacing = <!-- coupled wheels with assymetrical wheel spacing -->
| length = 
| over couplers = 
| width = 
| height = 
| frametype = 
| axleload = 
| leadingbogie/pony = <!-- load on leading bogie or pony wheel -->
| coupled all = <!-- when the load on all coupled wheels are the same -->
| coupled 1 = <!-- load on 1st coupled wheel -->
| coupled 2 = <!-- load on 2nd coupled wheel -->
| coupled 3 = <!-- etc. -->
| coupled 4 = 
| coupled 5 = 
| trail bogie/pony = <!-- load on trailing bogie or pony wheel -->
| tenderbogieload = <!-- load per tender bogie, use "Truck 1:<br>Bogie 2:" if different -->
| tenderaxle = <!-- use "Axle 1:", etc with "<br>" for line breaks -->
| weightondrivers = 
| locoweight = 
| tenderweight = 
| locotenderweight = 
| tendertype = 
| fueltype = 
| fuelcap = 
| watercap = 
| tendercap = 
| sandcap = 
| fireboxtype = <!-- Round-top, Belpaire, combustion chamber, etc. -->
| firearea = 
| boiler = <!-- Watson Standard no. x, etc -->
| boilertype = <!-- Domeless, etc -->
| pitch = <!-- height of boiler centreline above the railhead -->
| diameterinside = 90 in to 100 in (2286 mm to 2540 mm : S-1 class)
| lengthinside = <!-- distance between tube plates -->
| smalltubediameter = <!-- number of boiler tubes and their outside diameter -->
| largetubediameter = <!-- number of larger tubes (flues), if any, and their outside diameter -->
| boilerpressure = 220 Ib:15.5 kg/cm2(S-1 class) 200 Ib:14.1 kg/cm2(S Class )
| safetyvalvetype = <!-- Salter spring balance, Ramsbottom, Pop, etc. -->
| feedwaterheater = 
| totalsurface = 5270 sq.ft(489.6 m2 : S-1 class) (517.8 m2 : S class)
| tubearea = 4881 sp.ft(140.5 m2 : S-1 class)
| archarea = 
| fluearea = 
| tubesandflues = 
| fireboxarea = 262 sq.ft(S-1 class)
| superheatertype = 
| superheaterarea = 1512 sq.in(140.5 m2 : S-1 class) (123.5 m2 : S class)
| cylindercount = 
| cylindersize = 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)
| valvegear = 
| valvetype = 
| valvetravel = 
| valvelap = 
| valvelead = 
| transmission = 
| trainheating = 
| locobrakes = 
| locobrakeforce = 
| trainbrakes = 
| safety = 
| coupling = 
| maxspeed = 55-75 Mph
| poweroutput = 
| tractiveeffort = 
| factorofadhesion = 
| operator = [[Baltimore and Ohio Railroad]]
| operatorclass = S,S-1 and S-1a
| powerclass = 
| numinclass = 31 (S class) 125 (S-1)
| fleetnumbers = 6000–6030 (S class) 6100-6224 (S-1 Class)
| officialname = 
| nicknames = "big sixes"
| axleloadclass = 
| locale = Eastern [[United States]]
| deliverydate = 
| firstrundate = 
| lastrundate = 
| retiredate = 1926 (2) 1938 (15) 1953-1959 (Remainder)
| withdrawndate = 
| preservedunits = 0
| restoredate = 
| scrapdate = 1926,1938,1953-1959
| currentowner = 
| disposition = All Scrapped by 1959.
| notes = 
}}
'''Baltimore and Ohio Class S''' comprised three  [[class (locomotive)|classes]] of [[2-10-2]] [[locomotive]]s. 

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’s 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. They were nicknamed "big sixes" because until renumbering in 1954 their road numbers all began with 6. Locomotives numbered 6009 and 6030 were scrapped in 1925, and their boilers used to build new Class T [[4-8-2|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/S-1a's continued service until 1953-1959.

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

{{DEFAULTSORT:Baltimore And Ohio Class S}}
[[Category:Baltimore and Ohio locomotives|S]]
[[Category:2-10-2 locomotives]]
[[Category:Baldwin locomotives]]
[[Category:Lima locomotives]]
[[Category:Railway locomotives introduced in 1914]]
[[Category:Steam locomotives of the United States]]
[[Category:Scrapped locomotives]]
[[Category:Freight locomotives]]
[[Category:Standard gauge locomotives of the United States]]