翻译部分英文原文： The introduction of Conveyor BeltA conveyor belt may be defined as “a number of load carrying members bonded together with polymeric compounds (making up the car case); and protected from mechanical damage by elastomeric .The load carrying members usually consist of either a number of ply of woven fabric, a single solid woven fabric car case, or a single layer of parallel, equidistant steel cables.” At the onset, it must be stated that conveyor belting of any construction ,may be classified as Fire Resistant or Non-fire Resistant .In certain underground situation ,the former may be required by legislation or by accepted codes of Practice .For example ,in the U.K , coal mining industry ,only approved fire resisting belting may be used underground , most other developed countries have similar requirements . In addition there are many situations where the use of five resistant belting is recommended, for example, in complex mineral benefication plant. It is most important that in the early stages of design of any conveyor systems , the type of belt be determined ,ad differing characteristics of the two types may influence the design of other associated equipment and problems may be introduced if a change is required at some late date .The use to which any particular belt is to be subjected should be recorded in the purchase specification ;since the various properties of a belt may need modification to accommodate the sometimes conflicting demands of coefficient of friction ,ageing characteristics , moisture absorption ,etc. Also as a generally, a belt of rubber construction has a greater ability to absorb impact than one of fire resistant construction. There are three main constructional forms of belting: (a) ply construction, (b) solid woven construction (c) steel cord construction In the above constructions, (a) and (b), only the car-case provides the strength to carry the load and withstand the various operational stresses that are developed in the belt . Since the car-case is the most expensive element in the belt , it is important that the specification incorporates adequate means of protecting this most important element . In (c), the load carrying steel cords requires like protection. Additionally, there is the specialized design of belt used with the Cable Belt System which will be separately described when that arrangement is considered.（1）Ply Belt ConstructionWhen discussing ply belting ,the terms warp and weft often occur ,for the purpose of this sub-section it may be taken that :warp refers to the long itudinal strength of the belt .The lateral flexibility of the belt is always of importance in order that it may conform to the idler curve ,this being particularly so when deep trough idlers are to be used . The traditional belt car case consisted of woven natural fabric ,this now consist of one or more plies of synthetic fibers such as nylon or terylene ,the whole being vulcanized or fused together with the appropriate cover material . Such synthetic fibers are stronger than natural fibers. are thinner , more flexible allowing deeper through in the idlers , allow the use of smaller diameter pulleys and have a shorter elongation under high working tensions .The cover may be rubber in the case of non-fire resisting belts and PVC. Neoprene, etc, in the case of fire resisting types. The minimum cover on both sides of any belt should be not less than 0.8 mm, but for the transport of almost all minerals must be increased having regard to the material handled .For example, with moderately abrasive materials such as coal .rubble , ashes , etc. the minimum carrying side cover should be 2.4 mm with 0.8 mm on the pulley side cover should be 3.2 mm with 1.6 mm on the pulley side.Although national standards may vary, a belt type may be classified having regard to its strength, an example being given in the next sub-section.（2）Solid woven beltMuch of that said about ply belting applies to the solid woven form , but in the later ,the fibers from which the belt car-case is constructed are inter-woven ,then impregnated to give a solid form ,and to which appropriate covers are applied .The fibers may be of high tenacity nylon warp cotton pile and blended weft ,with certain qualities of belting employing a polyester warp . In the standard fire resisting form the cover may be PVC ,but this has certain limitations ,particularly in respect of conveying up inclines .To overcome this problem the cover may be polymer ,which offers the advantages of natural rubber . Such nit rile rubber covers are applied to both the carrying and the driving faces of the belt with consequently improved frictional characteristics which minimize load slier and afford increased driving traction . A further advantage is that such covers do not polish in services as does PVC. ply separation and gives excellent resistance to age wear ,further , its rot proof and resistant to minera