Electric mine hoists

Of primary importance in mine installations is the hoist, which has a very direct bearing on the successful operation of a mine. Conditions vary greatly with different mines, and especially in different localities. Such factors as depth, incline, the number of levels, permissible or desirable speeds, conditions of ore, etc., are always more or less special in each case. Veins of ore are never exactly duplicated, and the nature of the ground through which shafts are sunk may considerably modify permissible values. As mining laws are made by the different states they necessarily vary somewhat, and, even when not fully observed, they introduce factors which qualify the conditions of hoisting men and ore. The amount of timbering required is often of importance as relating to hoisting conditions. Methods of loading ore affect the time required, as also does the question of the use of cars or skips. Safety precautions must be very carefully considered, and the number of men in each mine, the number of compartments, and often the method of removing water from the mine must have careful consideration.