GB935012A - Improvements in and relating to coal cutting machines - Google Patents

Abstract

935,012. Mining-machinery. CLARKE, CHAPMAN & CO. Ltd., T. THOMPSON, and E. L. J. POTTS. Dec. 31, 1959 [Jan. 12, 1959], No. 1122/59. Class 68 (1). A coal plough comprises a number of cutting-tools, one above the other, which are so adjustable that the tool working on the most easily cut layer leads the other tools which are arranged to the rear of the leading tool to an extent depending on the hardness of the layer being cut. In Fig. 2, four tools 11a-11d are carried by a head 1, pivoted on a vertical axis on a tractive body 3, to present the operative cutters to the coal face and to relieve the trailing cutters therefrom, the tools being secured on the ends of shanks 13a-13d of non-circular section which are slidable in carriers 10 attached to the head 1, the tools being held in the positions of adjustment by studs 15a-15d which pass through holes 14. The body 3 is steadied by extensions 16 which move along the floor beneath the face conveyer. In a modification, the tools are pre-set, symmetrically about a vertical line central with respect to the plough, by mounting each tool on the ram of an hydraulic jack with a built-in pump operable by a detachable handle. In another modification, the adjustment of the tools is effected automatically according to the hardness of the layers encountered, the tools being each mounted on the ends of a plunger rod which has a central piston and projects at both ends from the cylinder. The cylinders are mounted in a vertical series and are interconnected by conduits in such manner that excess pressure built up by one tool meeting a hard layer is transferred to the cylinders of tools dealing with less hard layers, so that the first tool is pressed rearwardly and the other tools advance in the direction of cutting so that they all take positions in which they attack the soft coal first and progressively to the hardest coal last. In all the embodiments, the tools may be mounted on percussive units carried by the shanks 13a- 13d, or by the plunger rods. The units may be pneumatically or electro-hydraulically operated and may be vibrated constantly during the coal cutting, or only during a period when the tools are being automatically adjusted according to the hardness encountered, e.g. by a control actuated by an increase in pressure in the toolcarrying hydraulic cylinders caused by meeting hard material. The control may effect vibrations in all the percussive units, or only in the unit meeting the hard material.