Shop buildings are usually one-story struc tures, except that in the machine shop the lighter work may be done on a mezzanine floor at the side. Storehouses and pattern stores are usu ally several stories high. Modern buildings are largely of steel frame or reinforced-concrete, with large window areas of steel sash, and with monitor or saw-tooth roofs for light and venti lation. A power-house furnishes steam heat, water, compressed air and electric current light and power, although electric supply is often obtained from an outside ,source. Ma chine tools and other appliances are operated largely by electric motors. Auxiliary to the plant will be its water supply and sewerage, heat, light and power, sanitation and locker and wash-rooms for the workmen. Handling material between the several shops and depart ments may be effected by motor trucks, narrow gauge railways or small tractors hauling trailers on paved roadways.
Locomotives operate over fixed divisions, be tween certain points, the distance averaging 100 miles. At each end must be an engine terminal with facilities for cleaning the fire, supplying coal and water, inspecting and cleaning the en gine and making hght repairs, and turning it for the return trip. Coal and water supply must be provided also at points along the divi sion.
An engine which has just brought in a train and finished its trip goes to the engine terminal, where it takes water and coal if necessary and then has its fire cleaned or dropped at an ashpit If not at once sent to an outbound track it is moved to the engine-house to be inspected and cleaned and given light repairs, especially those reported by the enginemen. Inspection is done sometimes at a pit in advance of the ashpit The engine is held in the house until assigned for the return trip, when a new fire is lighted. Where no repairs are necessary, engines ready for service may be stored on outdoor parking tracks arranged radially or parallel. An en gine going out to its train usually takes coal, water and sand just before leaving, so that facilities must be accessible to both inbound and outbound engines. Other facilities include a machine shop, storehouse, sand drier and oil house. Also a rest room for the men, with quarters for engine crews whose homes are elsewhere.
Engine-houses on American railways are usually of the °roundhouse* type, being seg mental in plan, with radial tracks converging upon a turntable by which an engine can be transferred from any radial track to the ap proach track connecting the turntable with the yard tracks. Rectangular houses are used in some cases, with parallel tracks connected di rectly to an approach track or served by a trans fer table traveling at right angles to them. A
special design has short diagonal tracks open ing from a track extending along one side of the building. A turntable is like a revolving bridge and serves both to shift and turn loco motives. If this is not provided there must be a Y-track, forming a triangle, for turning en gines and cars. In Europe, engine-houses are generally rectangular with tracks parallel or radiating from a turntable inside the building. To provide against blockades there should be more than one track leading to the turntable.
Roundhouses rarely form a complete circle. They are of brick or concrete, with low roof, and have either double swinging doors or flex ible steel doors that roll up at the top. To carry off the smoke, especially when new fires are being started, each engine stands with its smokestack under a smokejack or hood, which extends through the roof. To avoid a nuisance, the smokejacks may be connected to a flue served by an exhaust fan and led to a tall chim ney or to a series of water-filled trays through which the gases rise and are discharged to the chimney while soot and dirt are retained. In such cases the smokestacks are lowered into contact with the engine smokestacks. A pit between the rails of each track permits men to go under the engines to inspect and repair them. Frequently a drop pit is provided for a truck with jack to take an axle and pair of wheels from under the engine. The machine shop is usually an annex to the engine-house and some times one of the radial tracks extends into this shop.
Water stations comprise mainly a pumping plant with elevated tank which may supply the engines directly by spouts or may distribute a gravity supply to water columns. These are tall stands having a horizontal pipe at the top, the latter capable of being swung across the tender of an engine and discharging into the tank. When not in use this pipe lies parallel with the tracks. Water that is hard or of scale-producing quality may be treated in a chemical plant before going to the elevated tank, this being far preferable to the practice of putting chemicals in the tender or boiler. Track tanks for supplying water to moving locomo tives were invented by John Ramsbottom, of England, in 1861 and are used on a number of main lines in the United States. The tank is a shallow pan about 20 to 24 inches wide and seven inches deep, laid upon the ties for a dis tance of 1,200 to 1,500 feet and provided with steam and circulating pipes to prevent freezing. A hinged pipe on the tender is lowered so that its mouth or scoop dips below the surface. The speed of the train causes the water to be driven up this pipe which ends in an elbow discharging the water downward into the tender tank.