An engine turn-table is a costly item in railway requirements, not only in the girder-work, but in the large amount of building in the side walls and centre pier, and an effort is always made to avoid the outlay unless the table can be placed where it may be of permanent use. In the construction of foreign railways, and in our colonies, where the lines are opened in sections as the work goes forward, the temporary arrangement shown in [Fig. 443] is frequently used instead of an engine turn-table. The sketch will almost explain itself. On the main line, A, B, C, D, switches are placed at B and C, from which turn out curved lines, uniting at the switches E. An engine proceeding from A, and passing round the curve B, E, G, then round curve G, E, C, and back along main line, D, C, B, A, will be turned round as efficiently as on a turn-table. The writer has used this arrangement abroad with great advantage. It involves very little work or expense beyond laying down the permanent way, and so soon as the
temporary terminus of the line has been advanced further ahead, the rails and sleepers can be lifted and used again elsewhere.
[Figs. 444 and 445] give sketch plan and section of a waggon turn-table which has been largely adopted. The centre should be securely fixed on a solid foundation of masonry, brickwork, or concrete. The deep outer cast-iron ring is made in segments, properly fitted and bolted together, and fastened down to the foundation course. The stop-checks are cast on to this outer ring. Two roads, at right angles to each other, are laid on the turn-table, so that waggons to or from the goods-shed have only to make one quarter turn of the table. The top is generally covered with either chequered iron plates or timber to give good foothold for the men and horses which have to pass over in moving the waggons. If properly balanced, the table is easily turned by men pushing at the opposite corners of the waggon, or by a horse and tail-rope, or by hydraulic power through a capstan. In many cases of bad or soft foundations these small turn-tables are erected on a strong framework of creosoted timber.
Carriage turn-tables are now very rarely used. With the old short four-wheeled carriages the moderate-size turn-table was convenient for transferring an extra carriage to or from a spare carriage-line alongside the making-up train at a platform, but modern carriages are now so much longer, some of them twice the length, or more, than formerly, that nothing less than an engine turn-table would be large enough for them. Sometimes a carriage traverser is used for this station work, but much more frequently these long carriages are shunted on or off the making-up train by simply running them in or out through the nearest switches and cross-over road.
[Fig. 446] is a sketch of a carriage-traverser, of length to suit an ordinary six-wheeled carriage. The length, however, may be extended to take on a bogie carriage or any other long carriage. The framing is made of wrought-iron or steel, well braced together. The carrying wheels, W, W, run upon rails laid at right angles to the running-line or siding, and the carriage is moved on to or off the traverser by means of the hinged ramps shown at R, R. A carriage, once on the traverser, may be moved across one or several lines of running road, according to the extent of traverser line laid down; and this appliance is very suitable for large terminal stations and carriage-repair shops. It
will be observed that the operations of the turn-table and the traverser are quite distinct. With the former a vehicle can be transferred from one line to another, and also turned completely round; but with the traverser the vehicles are simply moved in a parallel direction, from one line to another, and when it is necessary to turn or change a vehicle end for end, as in the case of a mail-bag-catching apparatus van or a special saloon, then resort must be had to a turn-table.
Cranes.—A large portion of the merchandise conveyed on railways must be lifted into or out of the trucks by cranes. The position, description, and capacity of these will depend upon the materials to be handled. Large slow-working powerful cranes will be necessary for raising heavy castings, large logs of timber, or massive blocks of stone; while the small quick-acting cranes will be more suitable for dealing with the lighter packages, casks, and bales.
[Fig. 44]7 shows a gantry or overhead crane, used for lifting heavy weights out of an ordinary road-waggon, carrying them a short distance, and then depositing them in a railway truck, or vice versâ. Double-flanged rollers, attached to the ends of the platform C, C, run upon the rails R, R, which are fixed on the top of the beams B, B, secured to the verticals A, A. The working length of the gantry is only limited by the number of the verticals, and this, being the fixed portion of the work, may be extended out to any distance required. The travelling or carrying girders of the platform C, C may be made of wrought-iron, steel, or timber. They must be strongly framed and braced together as a platform to carry the lifting machinery and weight lifted, and have convenient gearing for effecting the transverse or side-to-side movement, as well as a horizontal movement along the line of rails on top of the verticals. Where the fixed portion of the gantry is of considerable length, two or more travelling platforms can be used. In the sketch given above, the entire gantry is shown as made of timber, but iron or steel can be equally well adopted, and continuous masonry or brickwork walls may be built to serve as verticals.