附录一（英文）I.SHEARER LOADERS FOR LONGWALL MININGIn Europe， longwall mining is comprehensively mechanized by the almost exclusive use of shearer loaders and ploughs. In the Federal Republic of Germany ploughing has been applied to a greater extent than in other coutries .In spite of this ，the proportion of coal extracted by shearer loaders is steadily increasing .It accounted for 36 percent of the total national output in October 1977.There are a number of convincing reasons why shearer loaders are gaining ground. Their operation is essentionly more independent of the floor and roof conditions ，dirt bands and changing seam conditions than that of ploughs. Optimum adaptation of the cutting height，the fixed cutting depth， and better roof control are further arguments in favour of shearer loaders.In October 1976 the effective working time on a plough face was in the range of 35 percent ，compared with 48 percent on a shearer face. The average outputs reflect the aboxe figures (FRG October 19771130 t from a plough face ，1678 t from a shearer face).It should be noticed ， however， that shearer loaders are generally operating in seams of greater thickness.Shearer loaders are now available for seams ranging from 0.75 m to 4.50 m in thickness. The various machine versions for the respective operating conditions encountered are assembled from a great number of major components in accordance with the unit principle of construction.Eickhoff shearer loaders， for instance， can be equipped with longitudinal motors having ratings of 170，200，and 300 kw ，and 450 kw at present and 230 kw units will be available soon.The shearers travel on or alongside the conveyor . Ranging arms of different length from 740 mm to 2230 mm are available .The shearers can be manufactured to operate on various voltages and frequencies generally used ，with various haulage methods and speeds， and different drum speeds and drum design for various machine heights.Contrary to former years the manufacturers of such machines are therefore no longer in a position to produce identical machines in large series ，but are compelled to assemble the mining machines from a large number of existing components according to principles which require continuous revision and improvement ，and to integrate them into complete systems together with the face conveyor and roof supports as required by the mining conditions encountered.Although a high degree of development and great operational safety for the severe operating conditions underground have already been reached， efforts have to be made to develop the mining machines further with a view to meet the following future requirements：(1)increased outputs (and at the same time a further improvement in operational safety )， (2)Extension of the working range (e.g. into steeply inclined seams )， (3)Improvement of the ergonomical conditions (e.g. reduction of dust make and noise ).Increased Outputs The current trend is for more coal to be extracted from fewer faces. The output from some faces is already so high that even short stoppages on a face result in an enormous loss of output .The required increase of outputs from shearer loaders is therefore closely connected with the requirement for higher operational safety ，a better degree of utilisation and easier monitoring of all functions of the machine .The improvement in performance is therefore not limited to the development of more powerful motors ， haulgeaboxes ，gearheads，and ranging arms ，but also includes the electrical monitoring of the machines and eventually full automation.This also applies to the development of cutting tools， as the tool life and the tool costs are decisive for the performance of a machine .Outputs can also be increased by multi-machine operation on a face .The efficiency can be improved by the elimination of stable holes and by avoiding stoppages caused ，for instance ，by large lumps breaking out of the face and which must be crushed manually.It is also obvious that the limitation of the operating voltage to 1000 v sets a limit to performance and that the further increase of the nominal motor ratings will require the introduction of higher voltages.Extension of the Working Range Comprehensive experience has been gained with shearer loaders in level and slightly inclined seams or workings to the rise.The mining of thin seams is affected by inherent limitations set by the height of the conveyor ， the necessary clearance underneath the machine ， and the height of the machine itself .Thin seams can therefore only be extracted by shearer loaders if the machine travels alongside the conveyor. This results in guiding problems which can not be solved by the use of a guiding arrangement provided in the traveling track only. A solution eventually found was to trap the machine against the conveyor. This opened possibilities for the shearer loader in a seam thickness which so far was reserved for the p