The Mechanical Handling and Storing of Material

206 THE MECHANICAL HANDLING OF MATERIAL The exact form of ropeway which it may be found desirable to adopt, will no doubt vary widely with the nature of the ground and of the work required to be done. In the same way details of construction, such as the kind of material for the supports, will depend more or less on local conditions. In some cases wooden supports may be found quite sufficient, while in others iron may be preferable. Ropeways are very frequently used for conveying timber from distant forests remote from navigable waterways, in mountainous and roadless tracts of land where the con- ditions are such that the stately tree must either remain in its native forest, or if it is to serve man’s purpose, it must be brought forth over gorges and ravines by the only possible conveyor for such a purpose—the Ropeway. Ropeways may broadly be divided into two grand divisions, namely, Single and Double. In the first case the load to be moved is carried by an endless running rope forming the ropeway. In the second the load is suspended from a traveller or runner drawn along the fixed rope by a separate traction rope commonly known as the hauler. The subdivisions of these two main types are many, and are due to diverse con- ditions as regards ground and the load under which they have to work. There is no doubt that in planning a ropeway, particular attention must be paid to the ground, as well as to the loads that are to be carried. The Single Ropeway.—This system is the oldest and simplest, and in its most primitive form it has already been mentioned, as one was erected for the city of Dantzig in the middle of the seventeenth century. In this system one endless running rope is used, supported upon a number of roller supports carried upon trestles or standards. The rope passes at one terminal round a driving drum from 6 to 10 ft. in diameter, which gives the motion to the rope at a rate of speed of from 3 to 4 miles per hour ; the other terminal is similar, but instead of giving motion it keeps the rope tight by a suitable tightening gear. The loads are carried in receptacles fitted with simple curved hangers pivoted in a A shaped saddle, which holds sufficiently tight* by frictional contact to the rope, and therefore travels with the same. The suspended frame of the load-carrier is also fitted by the side of the A-shaped saddle, with the small grooved pulley which engages at the terminals with a shunt rail, and thus disengages itself from the running rope, and becomes stationary on this shunt rail for filling or emptying, after which it is pushed on to the returning rope. It is generally considered that the single ropeway is more suitable for short distances and moderate weights, and where the inclines to be negotiated do not exceed 1 in 3, nor the individual loads 5 to 10 cwt. With single ropes, spans of lengths greater than 200 to 300 ft. should be avoided, unless on very broken ground or over deep valleys where spans of considerable length are unavoidable. We shall, however, see in the succeeding pages that experts, who devoted their energy almost exclusively to single ropeway designs, have achieved much better results than the above, and that they do not hesitate to apply the single rope system to practically any conditions and capacities capable of being handled by a ropeway. We have seen the extreme simplicity of the single ropeway from the foregoing, and will now go a little more closely into the details already outlined. An endless wire rope would run round two terminal wheels or drums, the said rope being supported between these drums on suitable pulleys, the diameters of which would vary according to the size of the rope. These pulleys would be carried on posts or supports of iron or timber at a sufficient height to enable the carriers (as the sk'ps or other receptacles in which the material is conveyed are termed) to clear all obstacles, even when the rope may sag. These carriers hang from the rope