Abstract :
Special features of industry react on selection of equipment. Speed of conducting operations directly affects value of property; the mining personnel has a somewhat unique psychology; the cost of providing space underground is enormous. Certain requirements result and equipment must be selected accordingly. Compressed air has been the only power medium and still reigns supreme for rock drills. Electric power has captured the field for large, underground pumps, hoists, and fans, but not for miscellaneous service. Mines have, and always will have, a complete distributing system for compressed air. In the future, they will also have distribution system for electric power. Results of practical experience are outlined. Power cables should be of small capacity and all of the same size. Three separate types of protection should be used for overloads, short circuits, and grounds, respectively. Distribution is generally at 2800 volts but might, with advantage, be at 4000 volts, grounded neutral. Magnet switches have solved the problem of starting and controlling motors. Reduced voltage starting is undesirable. Sealed type bearings eliminate much bearing trouble. A new type of large hoist occupying the minimum of space is now being installed at the Park-Utah. The field of mechanical haulage is undeveloped, but conditions to be met are formulated. Mechanical loaders´ are beginning to receive serious attention.
