There is known a mining installation comprising a plurality of ploughs supported by a guide means attached to a conveyor and connected to a haulage means in the form of a chain passing over end sprockets. The haulage means connects to a reciprocatory means in the form of one or two hydraulic rams arranged parallel to the conveyor at the waste side thereof which cause the ploughs to reciprocate through a distance equalling the length of the stroke of a hydraulic ram (cf. United Kingdom Patent Specification No. 760,508; Cl. 68(1); published in 1956).
In the known installation, the haulage means can displace the ploughs through a distance equalling the length of the stroke of just one hydraulic ram. Therefore, to work a longwall face, many ploughs are required each utilized, however, not to its full capacity due to the conditions at the face which limit the output. Furthermore, the ploughs, all working at the same rate, are caused to move by a force which is only a fraction of the total pull exerted by the haulage means, this force changing inversely with the number of ploughs. The resulting low pull per plough enables the installation to cut only a narrow web so that neither an improvement in the degradation of the mineral mined nor a reduction of the power requirements and dust-forming tendency, as compared with a single-plough apparatus, are feasible to achieve.
The numerous ploughs the installation is provided with invite problems in adapting same to the remote or automatic control of the thickness of the web cut depending on the surface features of the seam floor.
Also known is another plough mining installation incorporating a face conveyor with a ramplike profile attached thereto, movable plough bodies which are fitted with nozzles emitting a fluid into the face under a high pressure and are interconnected by a flexible drive chain to form a common plough train, a driving means in the form of one or two hydraulic cylinders with a supply system which are immovably fitted to the conveyor frame and linked to the plough train, causing this to reciprocate on a guide means along the face through a distance equalling the length of the stroke of a hydraulic cylinder (cf. U.S. Pat. No. 4,198,098; Cl. 299/34).
It will be noted that this installation has much in common with the installation referred to above. This applies to the way of imparting the motive force to the ploughs, to arraning these into a train and to supporting the plough train on the frame of the installation. A salient feature of the last-named known installation is the hydraulic system feeding high-pressure fluid to the nozzles which emit it into the face. The use of the hydraulic working in stripping the coal enhances the efficiency of the installation but, at the same time, it limits the field of application thereof only to those cases where the mining conditions and sanitary regulations permit the use of hydraulicking.
USPTO Backgrounds
USPTO Backgrounds