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TRAMWAY
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TRAMWAY , a track or See also:line of rails laid down in the public roads or streets (hence the See also:American See also:equivalent " See also:street See also:rail-way "), along which wheeled vehicles are run for the See also:conveyance of passengers (and occasionally of goods) by See also:animal or See also:mechanical See also:power; also a See also:light roughly laid railway used for transporting coals, both underground and on the See also:surface, and for other similar purposes. The word has been connected with the name of See also:Benjamin See also:Outram, an engineer who, at the beginning of the loth See also:century, was concerned in the construction of tram roads, and has been explained as an See also:abbreviation for " Outram way." But this is clearly wrong, since the word is found much earlier. It appears to be of Scandinavian origin and, primarily to mean a See also:beam of See also:wood, cf. Old See also:Swedish tram, trum, which have that sense. In a will dated 1555 reference is made to amending a "higheway or tram " in See also:Bernard See also:Castle, where a See also:log road seems to be in question. In See also:Lowland Scottish " tram " was used both of a beam of wood and specifically of such a beam employed as the See also:shaft of a See also:cart, and the. name is still often given in See also:England to the wheeled vehicles used for carrying See also:coal in See also:mining. &' Tram-way," therefore, is primarily either a way made with beams of wood or one intended for the use of " trams " containing coal (see RAILWAY). Construction.—The first tramway or street railway designed for passenger cars with flanged wheels was built in New See also:York in 1832. The construction of this tramway does not appear to have been a success, and it was soon discontinued. In 1852 tramways were revived in New York by a See also:French engineer named Loubat, who constructed the track of See also:flat wrought-See also:iron rails with a wide, deep groove in the upper surface, laid on See also:longitudinal timbers. The groove, which was designed for See also:wheel flanges similar to those employed on See also:railways, proved dangerous to the light, narrow-tired vehicles of the American type. To meet this difficulty a step-rail consisting of a flat See also:plate with a step at one See also:side raised about s in. above the surface was designed and laid at See also:Philadelphia in 1855. When tramways were first introduced into England by G. F. See also:Train in 186o a rail similar to that laid at Philadelphia was adopted. This rail (fig. 1) was made of wrought-iron and weighed 50 lb per yard. It was 6 in. wide and had a step 4 in. above the See also:sole. The rails were 'spiked to longitudinal timbers, which rested on transverse sleepers, and they were laid to a See also:gauge of 4 ft. 82 in. Tramways of this type were laid at See also:Birkenhead in r86o, at See also:London in 1861, and in the See also:Potteries (See also:North See also:Staffordshire) in 1863. The See also:English public, however, would not tolerate the danger and obstruction caused by the step-rail, with its large See also:area of slippery iron surface; and the tram-way laid in London had to be removed, while those at Birkenhead and the Potteries were only saved by being repaid with grooved rails. Thus, while the step-rail became the See also:standard See also:form used in the See also:United States, the grooved-rail became generally adopted in See also:Europe. From the tramway point of view the step-rail has many advantages. A groove collects See also:ice and dirt, and an curves binds the wheel flanges, increasing the resistance to See also:traction. A grooved rail is, however, far less of a See also:nuisance to the
See also:ordinary vehicular See also:traffic, and it has come to be largely used in the See also:principal cities of See also:America.
After the passing of the Tramways See also:Act of 1870 the construction of tramways proceeded rapidly in England. A flat grooved rail supported on a longitudinal See also:timber and laid on a See also:concrete See also:bed was generally adopted. The paving consisted of See also: With the addition of the side flanges a greatly improved method of fixing the rail to the sleepers was adopted. The old vertical spike, which was a crude fastening, was replaced by a " See also:dog " or See also:double-ended side spike, one end of which was driven through a hole in the flange of the rail (fig. 2). This fastening was very strong and proved a See also:great improvement. The next See also:change was the use of See also:cast-iron chairs to support the rails, which were introduced by Kincaid in 1872. These led to a modification of the rail section, and instead of the two side flanges a rail with a central flange (fig. 3) which fitted into the cast-iron chairs was used. The chairs weighed about 75 lb each, and were spaced at intervals of about 3 ft. The See also:Barker rail laid in See also:Manchester in 1877 was somewhat similar to that shown in fig. 3, but a continuous cast-iron See also:chair was used to support it. The introduction of See also:steam traction about t88o, with its heavier See also:axle loads and higher speeds, was a severe test of the permanent way. The flat section laid on timber sleepers and the built-up rails of the Kincaid and Barker types began to be discarded in favour of the solid girder rail rolled in one piece. The solidity and depth of this section gave it great vertical stiffness, and its introduction materially assisted in solving the problem of providing a smooth and serviceable See also:joint. The merits of the girder rail soon caused it to be generally adopted, and although the design has been greatly improved it remains to-day the standard form of tramway rail used through-out the See also:world. At first difficulty was experienced in See also:rolling the heavier sections with thin webs and wide bases, but the introduction of See also:steel and improvements in the rolling See also:mills overcame these troubles. The early girder rails laid about 188o usually weighed from 70 to 8o lb per lineal yard, and were 6 or 62 in. deep. The groove varied from 1 to IB in., and the tread was about 11 in. in width. The See also:fish-plates were not designed to give any vertical support, and were merely used to keep the rail ends in line. The girder rails were either bedded directly on the foundation or spiked to timber sleepers which were buried in the concrete. The form of See also:head adopted for tramway rails in Europe has almost universally been one with the groove on one side. With this section the wheel flange forces out the dirt clear of the tread. In a few isolated cases a centre grooved rail has been used. As with railways, the See also:adoption of many different gauges has led to much inconvenience. This want of uniformity in the gauge is in some parts of the See also:country a great obstacle to the construction of inter-See also:urban lines. London and the larger provincial townsadopted the standard gauge of 4 ft. 82 in., but in many towns narrow gauges of 3 ft. or 3 ft. 6 in. were laid. See also:Glasgow and a few other towns adopted the gauge of 4 ft. 74 in. with a view of making the narrow grooved rail of the tramways available for railway wagons, but without,any real success. With the introduction of electric traction the See also:weight and See also:speed of the cars greatly increased, and experience soon proved that only the most substantial form of permanent way was capable of withstanding the See also:wear and See also:tear of the traffic. The early electric lines were laid with girder rails weighing about 75 lb per lineal yard. These proved to be too light, and, at the present See also:time, rails weighing from 95 to 110 lb per lineal yard are in See also:general use. The large number of rail sections designed a few years ago gave considerable trouble to makers of rails. The issue in 1903 by the See also:Engineering See also:Standards See also:Committee of a set of standard girder tramway rail sections was there-fore generally welcomed. The sections comprise rails of five different weights. Modified sections for use on curves were also published, together with a standard form of See also:specification. Fig.4 shows the section of the too lb. B.S. rail (No. 3). Tramway rails are generally ordered in 45 ft. lengths. Rails 6o ft. See also:long are sometimes used, but they are difficult to handle, especially in narrow streets. The rail See also:joints still prove the weakest See also:part of the track. Numerous See also:patents have been taken out for fish-plates and sole-plates of See also:special design, but none has proved quite satisfactory. The " Dicker " joint, in which the head of the rail on the ~....1f.-.4..f II ..._1 e' .~`.-- _-._.... in2' .See also:ate I 37 l inner Fish Plate. See also:Outer Fish Plate. a feet long,aa%lbs.welght a feet fong,a6tlbs.welght. Enlargement of A -2C (Reproduced by permission of the Engineering Standards Committee) tread side is partly cut away and the fish-plate carried up so that the wheel runs on its See also:top edge, and the " See also:anchor " joint, in which a See also:short piece of inverted rail is bolted or riveted to the undersides of the abutting rails, have been largely used. The latter makes a See also:good stiff joint, but when buried in concrete it interferes with the bedding of the rail as a whole, often causing it to See also:work loose in the centre. Various processes have also been introduced for uniting the ends of the rails by See also:welding. Electric welding was first tried in the United States about 1893, and has since been considerably used in that country. In this See also:process two specially prepared fish-plates are applied, one to each side of the joint. Each fish-plate has three bosses or projections, one in the centre opposite the joint and one near each end. By passing a heavy alternating current of See also:low voltage between the opposite bosses the fish-plates are welded to the rail. The current is obtained-from the line by means of a motor-generator and static transformer. Another process which has been used considerably in the United States, and at See also:Coventry and See also:Norwich in England, is the cast-welded joint. To make this joint the rail ends are enclosed in an iron See also:mould filled with molten cast-iron, which makes a more or less perfect See also:union with the steel rails. The great See also:drawback to these two processes is the costly and cumbersome apparatus required. The " thermit " process (see WELDING) does not require any large initial outlay, and has been applied to welding the joints on both old and new tracks. The cost of making each joint is about I. Points and crossings are used on a tramway to deflect a See also:car from one road to another. In the days of See also:horse traction no movable switch was used, the car being guided by making the horses pull the leading wheels in the required direction. With the introduction of mechanical traction a movable switch was fitted in one of the castings to act as a See also:guide to the wheel flanges. On See also:modern tramways the points consist of a pair of steel castings, one being a fixed or dummy point, and the other containing a movable switch. On a single track at passing places the cars in Great See also:Britain always take the lef t-See also:hand road, and a See also:spring is fitted to hold the movable switch to See also:lead in that direction. The bottom of the grooves at open points and crossings are raised so that the car wheel runs on its flange over the break in the tread of the rail. Double switch points ir-. which the two See also:tongues are connected are sometimes laid. In See also:recent years the See also:size and weight of the castings and the length of the movable switches have considerably increased. See also:Manganese steel is very generally used for the tongues and sometimes for the whole casting. Ordinary cast steel with manganese steel inset pieces at the parts which wear most quickly are a feature of the later designs. At some junctions the points are moved by electric power. While the form of concrete foundation remains the same as that laid at See also:Liverpool in 1868, far greater care is now given to the bedding of the rails. After the excavation has been completed the rails are set up in the See also:trench and carefully packed up to the finished level. The concrete is then laid and packed under the rail, generally for a depth of 6 in. When the surface is to be paved with stone setts bedded on sand the concrete may be See also:left rough, but where wood is to be laid the surface must be floated with See also:fine mortar and finished to a smooth surface. Both hard and soft wood blocks are used for paving. Wood should not be used unless the whole width of the See also:carriage-way is paved. Many different qualities of stone setts have been laid. Hard See also:granite such as that supplied from the quarries near See also:Aberdeen is the most suitable. In urban districts the road authorities almost always require the tramway surface, i.e. between the rails and for 18 in. on either side, to be paved. In country districts many tramways have been laid with only a sett edging along each rail, the See also:remainder of the surface being completed with either ordinary or tarred macadam. This construction, however, is only suitable on roads with very light traffic. After a tramway is laid, especially in a macadamized road, the heavy vehicular traffic use the track, and the wear is very much greater than on other parts of the carriage-way. Steam and See also:Cable Tramways.—Horse traction, especially in hilly districts, has many limitations, and early in the See also:history of tramways experiments were made both with steam cars and cable haulage. Although experimental steam cars were tried in England in 1893 the first tramways which regularly employed steam engines were French, though the engines were supplied by an English See also:firm. About 188o many improvements were made in the design of the engines employed, and this form of traction was adopted on several tramways in England. Beyondformed of concrete, with cast-iron See also:yokes spaced at intervals of 4 ft. to support the slot beams. The conduit was 19 in. deep by 9 in. wide. The slot was in. wide. The See also:running rails were of the ordinary girder type bedded in concrete. Fig. 5 shows a See also:cross-section of the track at a yoke. This form of construction is very similar to that employed in forming the See also:tube on a modern electric conduit tramway. At See also:Edinburgh and other places where a shallow conduit is used the supporting pulleys are placed in pits sunk below the general level of the tube. On the See also:Birmingham cable tramway, where the tube is 2 ft. 8 in. deep, pits are not required at the supporting pulleys. This reduces the difficulty of draining the conduit. The yokes in this See also:case are made of steel T-bars spaced 4 ft. apart. Electric Tramways.—See also:Electricity is now the standard See also:motive power for tramway service, and is applied in three See also:main ways: (1) the overhead or trolley See also:system; (2) the open conduit system; and (3) the surface contact or closed conduit system. (See also TRACTION.) On a tramway worked on the overhead principle current is supplied to the cars by two overhead conductors or wires. See also:Round See also:copper wires varying in size from o (0.324 in.) to 0000 (0.40 in.) Overhead S.W. gauge are generally used. With feeding points Trolley. at every mile, the o See also:wire is electrically sufficient on most roads, but from a mechanical point of view oo wire is the smallest it is desirable to erect. Wires having figure 8 or elliptical grooved sections have been employed, and have the See also:advantage of allowing the use of a mechanical clip See also:ear which is clear of the trolley wheel. The ordinary round wire is usually supported by a See also:gun-See also:metal or gun-metal and iron ear grooved to See also:fit the wire, which is soldered or sweated to it. In Great Britain the overhead conductors are required by the See also:board of See also:trade to be divided into See also:half-mile sections. The wires on adjoining sections are connected by section insulators. These consist of gun-metal castings in two parts, insulated from each other. The line wires are clamped to the metal ends. The continuity of the path of the trolley wheel is provided for on the underside of the insulator by fixing a hardwood See also:strip between the ends or by the ribs on the castings with See also:air gaps. The trolley wires are supported by ears either from span wires which extend across the roadway between two poles or from See also:bracket arms carried on a See also:pole on one side only of the road. The span wires and short bracket suspension wires are also insulated, so that there is double insulation between the conductor and the pole. The overhead conductors are usually hung about 21 ft. above the rails. (For See also:catenary suspensions see TRACTION.) The poles which carry the span wires and the Bracket arms are placed not more than 40 yds. apart and are generally placed at the edge of the kerb. They are built up of three sections of steel tubes, one overlapping the other; the joints are shrunk together while hot. A cast-iron case is used to improve the See also:appearance of the pole, and cast-iron collars hide the joints. Standard specifications for poles have been issued by the Engineering Standards Committee. When permission can be obtained the span wires are sometimes supported by rosettes attached to the walls of the houses on either side of the street. This method has been largely adopted in See also:Germany, ---- • • -810'widlhorSmglebock s1 "Ills IBM . Milt= Between Yoke (From T. Arnall's Permanent Was for Tramways and Street Railways, by permission of The Railway Engineer.) 4 8i- ---A 1.----4 Al Yoke requiring a better constructed track it does not necessitate any modifications in the general design of the permanent way. The first cable tramway was constructed at See also:San Francisco in 1873. In England the first cable system was a short length at See also:Highgate in 1884. Cable tramways were also laid down at Edinburgh, Birmingham, See also:Matlock and See also:Brixton (London). Cable traction, with the expensive track construction it necessitates, and the limited speed of haulage, belongs to the past. Only gradients too severe to be worked by ordinary See also:adhesion will in the future justify its use. The construction of the conduit or tube in which the cable runs adds very considerably to the cost of the permanent way. Additional information and CommentsThere are no comments yet for this article.
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