The Mechanical Handling and Storing of Material

256 THE MECHANICAL HANDLING OF MATERIAL iffh -f=rr=5- Figs. 370 and 371. Angle Station of Rope Haulage Plant. 67 fl the track. These levers are coupled together beneath the line so that both pairs must move together. Fig. 373 shows the levers in both positions, one being in dotted and the other in full lines. It will be seen that they stand at a certain angle to each other. Their action is as follows : As the truck descends, the axles of the wheels depress the short levers, and thus raise the longer and lower levers in an upright position standing at right angles to the track. As soon as the tub has left the first levers, these will swing back to their original position, and thus pull down the long lever for the tub to pass over unhindered. Should, however, the tub descend at an unusual speed, as would be the case if a truck became disengaged, it would reach the lower levers before they had time to descend and thus stop the tub, the shock being again taken by a powerful volute spring. The distance be- tween the two pairs of levers must always be accurately ad- justed to the size of the tubs and their normal speed. The driving gear of a similar installation built by the same designer, and for the same firm, is shown in Figs. 374 and 375. This plant is for handling 150 tons of iron ore per hour, but is capable of dealing with 300 to 360 tons. The driving gear is actuated by an electro-motor, and the rope pulleys are between 12 and 13 ft. in diameter. The transmission from the motor to the rope wheels is effected by three pairs of spur wheels and three countershafts, thus reducing the speed of the motor to give the rope a travel of 200 ft. per minute. After the rope (which is in. in diameter) has passed over the two main pulleys a and B, it is conducted over a horizontal pulley c, which is mounted on a carriage and connected with a weight which is suspended on a chain from a tower built for the purpose. This is necessary in order to take up the stretch of the rope, which is 32,800 ft. long. The rope itself has a breaking strain of 29 tons, but it is only strained during the ordinary working to a load of 4 tons. The trucks are put on the lines at a pitch of about 35 to 40 yds. Each truck holds 1| tons of ore, and the incline of the line is very slight. Further interesting examples of rope haulage1 are found at Düddingen, Lorraine, for handling the iron ores from the Minette mining districts, one of the principal sources of iron ore in Germany. The ore deposits are so situated that they have to be 1 From an article by Fr. Tillmann, Zeitschrift des Vereins deutscher Ingenieure, 12th March 1910.