<Dl> <Dd> 1 Tender--Container holding both water for the boiler and fuel such as wood, coal or oil for the fire box . </Dd> <Dd> 2 Cab--Compartment where the engineer and fireman control the engine and tend the firebox . </Dd> <Dd> 3 Whistle--Steam powered whistle, located on top of the boiler and used for signalling and warning . </Dd> <Dd> 4 Reach rod--Rod linking the reversing lever in the cab (often a johnson bar)) to the valve gear . </Dd> <Dd> 5 Safety valve--Pressure relief valve to stop the boiler pressure exceeding the operating limit . </Dd> <Dd> 6 Generator--electrical generator driven by small steam turbine, for locomotive lighting and headlight . </Dd> <Dd> 7 Sand dome--Holds sand that is dropped on the rail in front of the driving wheels to improve traction, especially in wet or icy conditions . </Dd> <Dd> 8 Throttle Lever / Regulator--sets the opening of the regulator / throttle valve (#31) which controls the pressure of steam entering the cylinders . </Dd> <Dd> 9 Steam dome--Collects the steam at the top of the boiler so that it can be fed to the engine via main steam pipe, or dry pipe, and the regulator / throttle valve </Dd> <Dd> 10 Air pump or compressor--compresses air to operating the brakes (train air brake system). This is sometimes called a Westinghouse pump or Knorr pump after George Westinghouse and Georg Knorr . Single stage steam - driven air compressor or higher capacity two - stage, cross-compound compressors were used </Dd> <Dd> 11 Smokebox--Collects the hot gases that have passed from the firebox and through the boiler tubes . It may contain a cinder guard to prevent hot cinders being exhausted up the chimney . Usually has a blower to help draw the fire when the regulator is closed . Steam exhausting from the cylinders is also directed up the chimney to draw air through the firebed while the regulator is open . <Dl> <Dd> Blower a circular pipe below the chimney petticoat pipe, with holes to blow steam upwards . Provides a draught to maintain adequate combustion when locomotive is stationary and the blastpipe is not effective . This draught also prevents smoke and flames from entering the cab . </Dd> <Dd> Petticoat pipe is a pipe with a bellmouth - shaped end extending into the smokebox and the other end in the smoke stack . Its function is to enhance and equalize draft through the boiler tubes . </Dd> </Dl> </Dd> <Dd> 12 Steam pipe--carries steam to the cylinders . </Dd> <Dd> 13 Smoke box door--Hinged circular door to allow service access to the smoke box to fix air leaks and remove char . </Dd> <Dd> 14 Hand rail--Support rail for crew when walking along the foot board . </Dd> <Dd> 15 Trailing truck / Rear bogie--Wheels at the rear of the locomotive to help support the weight of the cab and fire box . </Dd> <Dd> 16 Foot board / Running board--Walkway along the locomotive to facilitate inspection and maintenance . UK terminology is Footplate . </Dd> <Dd> 17 Frame--Carries boiler, cab and engines and is supported on driving wheels and leading and trailing trucks . The axles run in slots in the frames . American locomotives usually have bar frames (made from steel bar) or cast steel frames (see Bury bar frame locomotive), while British locomotives usually have plate frames (made from steel plate). </Dd> <Dd> 18 Brake shoe and brake block--rub on all the driving wheel treads for braking . </Dd> <Dd> 19 Sand pipe--Deposits sand directly in front of the driving wheels to aid traction . </Dd> <Dd> 20 Side rods / Coupling rods--Connects the driving wheels together . </Dd> <Dd> 21 Valve gear / motion--System of rods and linkages synchronising the valves with the pistons and controls the running direction and power of the locomotive . </Dd> <Dd> 22 Main rod / Connecting rod--Steel arm that converts the horizontal motion of the piston into a rotary motion of the driver wheels . The connection between piston and main rod is a cross-head which slides on a horizontal bar behind the cylinder . </Dd> <Dd> 23 Piston rod--Connects the piston to the cross-head . </Dd> <Dd> 24 Piston--Driven backward and forward within the cylinder by steam pressure, producing motion from steam expansion . </Dd> <Dd> 25 Valve--Controls the supply of steam to the cylinders, valve position relative to piston determined by valve gear connected to driving wheel . Steam locomotives may have slide valves, piston valves or poppet valves . </Dd> <Dd> 26 Valve chest / steam chest--Valve chamber adjacent to cylinder, contains passageways to distribute steam to the cylinders . </Dd> <Dd> 27 Firebox--Furnace chamber that is built into the boiler and surrounded by water . Various combustible materials can be used as fuel but the most common were coal, coke, wood or oil . </Dd> <Dd> 28 Boiler tubes--Carry hot gasses from the fire box through the boiler, heating the surrounding water . </Dd> <Dd> 29 Boiler--container almost full of water with air space above . The water is heated by hot gases passing through tubes, producing steam in the space above the water . </Dd> <Dd> 30 Superheater tubes--Pass steam back through the boiler to dry and superheat the steam for greater efficiency . </Dd> <Dd> 31 Regulator / Throttle valve--Controls the amount of steam delivered to the cylinders (also see #8), one of two ways to vary power of the engine (throttle governing) </Dd> <Dd> 32 Superheater--Feeds steam back through boiler tubes to superheat (heat beyond boiling temperature of water at boiler pressure) the steam to increase the engine efficiency and power . </Dd> <Dd> 33 Chimney / Smokestack--Short chimney on top of the smokebox to carry the exhaust (smoke) away from the engine so that it doesn't obscure the footplate crew forward view . Usually extended down inside the smokebox - the extension is called a petticoat . Some railways, e.g. the Great Western Railway, fitted a decorative copper cap to the top of the chimney . </Dd> <Dd> 34 Headlight--Light on front of the smoke box to illuminate track ahead and warn approach of locomotive to other track occupants . </Dd> <Dd> 35 Brake hose--Air or vacuum hose for transmitting brake system pressure / vacuum to train brakes . See air brake and vacuum brake . </Dd> <Dd> 36 Water compartment--Container for water used by the boiler to produce steam . </Dd> <Dd> 37 Coal bunker--Fuel supply for the furnace, may be wood, coal / coke or oil . Fed to the firebox either manually or, for bigger fire grates, by mechanical stoker . </Dd> <Dd> 38 Grate--Holds the burning fuel and allows ash to drop through . </Dd> <Dd> 39 Ashpan hopper--Collects the ash from the fire . </Dd> <Dd> 40 Journal box--Housing for the plain bearing on a Driving wheel axle . </Dd> <Dd> 41 Equalising beams / Equalising levers / Equalising bars--Part of the locomotive suspension system, connected to leaf springs, free to pivot about their centre which is fixed to the frame . Function is to even out weight carried on adjacent axles on uneven or poorly laid tracks . </Dd> <Dd> 42 Leaf Springs--Main suspension springs for the locomotive . Each driver wheel supports its share of the locomotive weight using a leaf spring which connects the axle journal box to the frame . </Dd> <Dd> 43 Driving wheel / Driver--Wheel driven by the pistons to move the locomotive . Drivers are balanced with weights to reduce unwanted motion of the locomotive . There are 3 sets of driving wheels in this example . </Dd> <Dd> 44 Pedestal or saddle--Connects a leaf spring to a driver wheel journal box . </Dd> <Dd> 45 Blast pipe--Directs exhaust steam up the chimney, creating a draught that draws air through the fire and along the boiler tubes . </Dd> <Dd> 46 Pilot truck / Leading bogie--Wheels at the front to support weight of boiler front end / smokebox and reduce flanging forces between front driving wheels and rail when rounding curves . </Dd> <Dd> 47 Coupling / Coupler--Device at the front and rear of the locomotive for connecting locomotives and rail cars together . <Dl> <Dd> Snifting valve (not shown)--An anti-vacuum valve which permits air to be drawn through the superheater and cylinders which allows the engine to coast freely when the regulator is closed . </Dd> </Dl> </Dd> </Dl> <Dd> 1 Tender--Container holding both water for the boiler and fuel such as wood, coal or oil for the fire box . </Dd> <Dd> 2 Cab--Compartment where the engineer and fireman control the engine and tend the firebox . </Dd> <Dd> 3 Whistle--Steam powered whistle, located on top of the boiler and used for signalling and warning . </Dd>

Where does steam come out of a train