Steam locomotive components

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Main components found on a typical steam locomotive include:

File:Diagram_of_steam_locomotive_components_(March_2021_version).tif|thumb|center|800px|The main components of a typical steam locomotive. Click or hover over numbers to see names. ()

rect 133 15 172 57 Tender

rect 538 17 575 57 Cab

rect 667 15 708 57 Safety valve

rect 715 15 754 55 Reach rod

rect 754 15 789 55 Whistle

rect 797 13 836 57 Dynamo

rect 876 9 917 57 Sand dome

rect 923 9 963 55 Throttle lever / Regulator

rect 1009 11 1056 57 Steam dome

rect 1152 9 1194 57 Air pump / Air compressor

rect 1220 9 1266 55 Smokebox

rect 1277 9 1324 57 Steam pipe

rect 1338 11 1383 55 Smokebox door

rect 593 409 640 457 Trailing truck / Rear bogie

rect 645 409 688 457 Foot board / Run board / Running board / Tread plate

rect 695 409 741 457 Frame

rect 752 409 797 455 Brake shoe / Brake block

rect 849 412 891 455 Sand pipe

rect 895 412 935 455 Coupling rods / Side rods

rect 993 410 1037 453 Valve gear

rect 1041 410 1083 457 Connecting rod / Main rod

rect 1102 410 1148 457 Piston rod

rect 1150 410 1187 457 Piston

rect 1185 410 1231 457 Cylinder

rect 1281 412 1322 455 Valve

rect 1320 409 1361 457 Valve chest / Steam chest

rect 697 483 743 531 Firebox

rect 810 481 858 531 Boiler tubes and flues

rect 878 481 924 532 Boiler

rect 930 481 974 532 Superheater tubes

rect 1004 481 1052 536 Throttle / regulator valve

rect 1096 483 1143 536 Superheater

rect 1229 483 1277 531 Smokestack / Chimney / Funnel

rect 1298 481 1350 531 Headlight

rect 70 860 122 906 Brake hose

rect 131 862 179 908 Water compartment

rect 368 860 414 908 Coal bunker

rect 571 860 617 908 Grate

rect 636 860 690 908 Ashpan hopper

rect 784 860 834 906 Journal/axle box

rect 849 860 889 906 Equalising beams / Equalising levers / Equalising bars

rect 897 860 935 906 Leaf springs

rect 937 858 982 906 Driving wheels

rect 1035 862 1082 904 Pedestal / Saddle

rect 1118 863 1165 908 Blast pipe

rect 1215 860 1263 910 Pilot truck / Lead truck

rect 1289 862 1338 906 Pilot / Cowcatcher

rect 1348 862 1396 908 Coupler / Coupling

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The diagram, which is not to scale, is a composite of various designs in the late steam era. Some components shown are not the same as, or are not present, on some locomotives – for example, on smaller or articulated types. Conversely, some locomotives have components not listed here.

Details of the components

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Tender<br />Attached rail vehicle that holds both water for the boiler and fuel such as wood, coal, or oil.

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Cab <br />Footplate <br />Compartment where the engineer (US+) / driver (UK+) and fireman control the locomotive and tend the steam supply and firebox.

thumb|Most controls are mounted on the boiler's backhead

a throttle lever or regulator, which controls the amount of steam entering the cylinders

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Brake shoe / brake block<br />Cast iron or composite material that rubs on all the driving wheel treads for braking.