The Mechanical Handling and Storing of Material

SELF-EMPTYING RAILWAY WAGONS 495 usually conveyed from mines to the manufacturing districts, hence special trucks with hopper bottoms must generally be returned empty, as they are less suitable for the conveyance of ordinary goods. But we shall see later on that there are on the market some types of hopper wagons which are easily convertible into level-floor wagons for the conveyance of ordinary merchandise. In some cases the turntables are not of the requisite size. It will thus be seen that apart from the private ownership of 10-ton wagons, co-operation between the trader and the railway companies is essential to the successful introduction of self-unloading trucks, and so far traders have been slow to recognise the advantages of this system, and are, to say the least of it, lukewarm in regard to the necessary alterations of terminal plant. Frequently, the sidings are too narrow to admit the larger trucks, for though the wheel base may be the same as in the existing 10-ton wooden wagons, the truck is generally some inches wider. Thus it will be seen that at the coal ports some alterations in the loading appliances will be necessary before the general adoption of such wagons is possible. The use of self-unloaders can only be beneficial to its fullest extent in conjunction with other mechanical devices and suitable terminal plant for handling the material when unloaded. The most economical method of disposing of the contents of the truck is to raise the railway siding to a sufficient height above the point at which the material is to be unloaded to allow the latter to fall by its own gravity as soon as the self-emptying truck has been opened. In all other cases elevators with suitable feeding devices (which have been fully dealt with elsewhere) will be necessary. The 15-Ton Hopper-Bottomed Self-Discharging Iron-Ore Wagons of the Alquife Mines and Railway Co., Ltd., which were built by Messrs Hurst, Nelson, & Co., Ltd., are of special interest. These wagons are used for conveying iron ore from the company’s mines at Alquife, in the South of Spain, to the shipping port of Almeria. The company have constructed a pier at the latter place, and the wagons had to be specially designed to meet both the loading arrangements at the mines and the discharging into the steamers. Owing to the very steep gradients which these wagons have to traverse on the South of Spain Railway Co.’s lines, a certain portion had to be fitted with brakesman’s boxes, which are equipped with powerful screw brakes in addition to the vacuum brake. The wagons, 160 in number, are double hoppered, and built entirely of steel. A special feature is the arrangement of bottom doors. Close attention has been given to avoiding the waste during transit of any ore, a portion of which is in the form of a fine powder. The principle of the door arrange- ment consists in the raising at the centre of a pair of V-shaped arms, which are attached to brackets riveted on to the bottom doors. The motion is transmitted by a cross-shaft to a centre lever, which is in turn connected to the door arms by a separate lever which acts on a fulcrum. Suitable arrangements are provided at one side of the wagon to regulate the amount of travel of the doors, and also to secure them in the open and shut positions. The wagons are fitted with side spring buffers, screw couplings, and safety chains, and are quite equal to the class of rolling stock used in this country. The Lehoen Pressed Steel Co., of Pittsburg, U.S.A., and the Pressed Steel Car Co. were probably among the first to build these trucks largely of pressed steel parts. At the present time over 400,000 trucks, the bodies of which have been built principally of pressed steel, are in use in the United States. These trucks are built with capacities of from 30 to 70 cub. yds.; those from 30 to 50 are used for coal, while the largest, up to 70 yds. capacity, carry coke. It must not be supposed that these steel wagons are more expensive than the old-fashioned wooden ones, or that they compare unfavourably when the capacity per