TELPHERAGE
On most ropeways the skips or other conveyances are moved along the fixed ropes by trailing ropes working round drums driven by steam and controlled by brakes. But the employment of electricity has provided a system called telpherage, in which the vehicle carries its own motor, fed by current from the rope on which it runs and from auxiliary cables suspended a short distance above the main rope. "Telpher" is a term derived from two Greek words signifying "a far carrier," since the motor so named will move any distance so long as a track and current is supplied to it. The carrier—for ore, coal, earth, barrels, sacks, timber, etc.—is suspended from the telpher by the usual hook-shaped support common to ropeways, to enable the load to pass the arms of the posts or trestles bearing the rope. The telpher usually has two motors, one placed on each side of a two-wheeled carriage so as to balance; but sometimes only a single motor is employed. Just above the running cable is the "trolley" cable, from which the telpher picks up current through a hinged arm, after the manner of an electric tram. The carriers are controlled on steep grades by an electric braking device, which acts automatically, its effect varying with the speed at which the telpher runs. The carrier wheels, driven by the motors, adhere to the cable without slipping on grades as severe as three in ten, even when the surface has been moistened by rain. "In order to stop the telpher at any desired point, the trolley wire is divided into a number of sections, each controlled by a switch conveniently located. By opening a switch the current is cut off from the corresponding section, and the telpher will stop when it reaches this point. It is again started by closing the switch. At curves a section of the trolley wire (i.e. overhead cable for current) is connected to the source of current through a 'resistance' which lowers the voltage (pressure of the current) across the motors at this point. Thus, upon approaching a curve, the telpher automatically slows down, runs slowly around the curve until it passes the resistance section, and is then automatically accelerated."[20]
The telpher line is very useful (for transporting material considerable distances) in districts where it would not pay to construct a surface railway. On plantations it serves admirably to shift grain, fruits, tobacco, and other agricultural products. Then, again, a wide field is open to it for transmitting light articles, such as castings and parts of machinery, from one part of a foundry or manufactory to another, or from factory to vessel or truck for shipment. When coal has to be handled, the buckets are dumped automatically into bins.
The telpher has much the same advantages over the steam-worked ropeway that an electric tram has over one moved by an endless cable. Its control is easier; there is less friction; and the speed is higher. And in common with ropeways it can claim independence of obstructions on the ground, and the ability to cross ravines with ease, which in the case of a railway would have to be bridged at great expense.