The Mechanical Handling and Storing of Material

432 THE MECHANICAL HANDLING OF MATERIAL uncoupled, and the load automatically held in that position, so that any further winding of the rope will move it in a horizontal direction. When the load has been discharged, the traveller returns, its speed being controlled by a brake, until it has reached the point where it fixes itself, after which the further slackening of the rope will permit the descent of the skip. The inclines of the girder are in this case 1 in 8; but this not being sufficient to allow of the traveller going back on its own account, a travelling rope with a balance weight had to be used for the return of the empty skip as shown. The traveller is represented in Fig. 607 at the moment when it reaches the lowest point determined by the fixture a which enters into the space provided for it in lever bv and couples itself as shown in dotted lines as soon as the traveller reaches the end of its journey. The lever b.2 is moved simultaneously, thus giving rod c a downward motion. This action also Fig. 600. moves lever dy which swivels round point e to the right at the top, and to the left at its lower end. This action releases the pulley and the fall-block with the load. The skip is now descending, and whilst doing so the head or traveller is held in position by lever bv After the skip has been filled and raised, the projecting spindles of the fall- block touch the forked end of rod c, which is thereby raised, so that b, bv and d are all replaced in their original position. Thereupon a is released by b, and lever d again holds the load, which, with the traveller, can proceed to the right. The skip is made to discharge its load automatically. It has a natural tendency to tip forward, but is prevented from tilting by the levers, which rest in grooves on the sides of the skip. Fig. 608. Fig. 607. The traveller is fitted with levers gg, which are held in position by springs in the tube h. One end of the lever is fitted with rollers ii. These rollers touch trippers kk which are fixed in the discharging position. Thus the levers g g will be lowered by the incline on trippers kk until they come in contact with levers ff and release the skip, allowing it to discharge itself. This method of unloading is, of course, only used when minerals are being handled, as a fall from a height would in the case of coal be detrimental. Fig. 608 shows a cross section through the trestle bridge of the transporter. 1 he