插图：In this paper, the major components associated with vertical to near-vertical shafts using hoists and cable-suspended conveyances are described briefly. The term shaft hoisting system is used to describe collectively the openings and the equipment by purpose, by configuration, by ground support, and being considered, by excavation method.In addition to the five major hoisting components, Edwards (1988) has identified an additional 277 subcomponents. The number of subcomponents and their interrelationship with the main components are indicative of the complexity involved with the design of shaft hoisting systems.A brief description of each of the above main components is now presented. In the following segments, information on the design and technical considerations to be examined when selecting a particular component is presented in more detail.1.HoistsThere are two basic types of hoists in common use today. These are the drum hoist in which the hoist rope is stored on the drum, and the friction hoist in which the rope passes over the wheel during the hoisting cycle. Within each category there are several variations.Drum hoists are usually located at some distance from the shaft and require a head frame and sheaves to center the hoisting ropes in the shaft compartment. Friction hoists may also be located directly over the shaft and, depending upon the wheel diameter, may require deflection sheaves to center the rope in the shaft compartment.2.ConveyancesConveyances used in mining operations are classified according to their use.Those for handling personnel and material are generally termed cages. Conveyances for handling broken ore or coal and waste are termed skips. Combination skip-cages are used in some areas. A counterweight may also be considered a conveyance.

 2/2   首页 上一页 1 2

外语 大学英语 大学专业英语教材

在线阅读