The Mechanical Handling and Storing of Material

276 THE MECHANICAL HANDLING OF MATERIAL to form a rigid, smooth, and lasting rail for the load to run upon, whilst the latter, which would not be exposed to much actual external wear, but mainly to that due to tension, should be composed of thin wires of good quality steel, in order to give flexibility and strength. Now with a single ropeway both demands of tensile strength and rigidity are made upon one and the same rope, and it must therefore be apparent that a rope must be chosen which meets these demands. As it is difficult to arrive at a happy medium to meet such diverse conditions, the single ropeway is under a disadvantage. The single Fig. 401. Single Rope Carrier employed by Ropeways, Ltd. rope, though always running, is working under similar conditions to the fixed rail rope of the double ropeway; only instead of the rope with its load running over stationary rollers as in the first case, the running rollers with their load pass over the stationary rope in the second case. The stationary or rail rope of the double ropeway may be subjected to greater local strain, and consequently wear more at certain points of its length, and being a fixture may wear principally on the uppermost side, whilst the single rope, which Fig. 402. Grouped Sheave Mountings with Balance Beams. constantly travels the whole route, must of necessity wear equally on the whole of its length, as every portion must negotiate any point causing extra wear, and as it always revolves slowly round its own axis it is worn equally all round. The rail rope of the double ropeway can of course be relaid froin time to time, whereby this defect might be minimised. If we summarise the foregoing we find that the two ropes of the double ropeway can be better adapted to their diverse requirements than the single rope, which has to combine both requirements in one rope. On the other hand, the rail rope of the