Patent GB-1222229-A (GB)
Title: Apparatus for displacing step-by-step a mining machine along a cutting face
IPC: E21C29/02
Filed: 1968-10-25
Abstract: 1,222,229. Step-by-step hydraulic jacks. CHARBONNAGES DE FRANCE. 25 Oct., 1968 [27 Oct., 1967], No. 50884/68. Heading B8J. [Also in Division E2] As shown in Fig. 19 an arc-winning machine M is displaced step-by-step along the cutting face (not shown) by a device comprising a double-acting jack 7 and a gripping hand associated with a longitudinal guide 9 through upper and lower jaws 3, 11, respectively. The gripping hand can be clamped to the guide 9 by pressure from a source P 1  supplied through a conduit 42 to single acting jacks 40, pistons 41 coming into contact with body 2. While the hand is clamped, pressure from a source P is supplied, as shown, through a conduit 47 to extend the jack 7 and move the machine M in the direction of the arrow F<SP>1</SP>. When valve 18 is changed over and pressure from the source P applied to conduit 48 valve 43 is operated to connect the jacks 40 to tank R 1  to release the grip on the guide 9. Since the machine M is heavier than the gripping hand retraction of the jack 7 draws the gripping hand towards the machine M in the direction of the arrow F<SP>1</SP>. The valve 18 is changed over again and the cycle repeated as the valve 43 is also changed over automatically. The valve 18 may be actuated automatically at the end of each stroke of the jack 7 by known devices (not shown). A manually-operated distributer 44 acts as a direction-reversing device. Fig. 1 shows a unidirectional gripping hand operated by the wedging action of rollers 4 in imprints 13, being loaded by spring push-rods 16. Fig. 10 shows a modification of this arrangement wherein the gripping hand may be made to grip in either direction. The rollers 4 may be loaded in either direction by spring pushrods 16 or 16<SP>1</SP>, the direction being selected by a lever 21 which may set a pillar either in position 20G or 20D. Fig. 13 shows an embodiment having two gripping hands with symmetrical imprints for the rollers and selector devices (not shown) as in Fig. 10. Pistons 8G, 8D of double-acting jacks with bodies 6G, 6D are coupled by a synchronizing rod 22 and fixed on the machine M by driving elements 10G, 10D. Channels 23, 24 are pierced in the rod 24 and in the pistons 8G, 8D. Two pulleys 25, 26 fixed on the machine M are mounted each side of the assembly comprising the two gripping hands 1G, 1D. A closed chain passes round the two pulleys 25, 26 and is fixed to the jack bodies 6G, 6D at N G , N D  respectively. With valve 18 set as shown and the rollers urged in the direction of arrows F G , F D  pressure is applied to the conduit 23 effecting locking of gripping hand 1G and unlocking of gripping hand 1D. The machine M and hand 1D are thus displaced in the same direction F. At the limit of travel the machine M has moved a distance equal to the travel of the pistons while the hand 1D has been displaced twice this amount. The hands 1G, 1D are then in their closest positions. Reversal of the direction of pressure (changeover of valve 18) causes hand 1D to grip and hand 1G to slide, the machine again moving in the direction F while the hands 1G, 1D are separated. The cycle can then repeat. If the rollers are urged in the direction opposite to F G , F D  the machine M is moved in the direction F<SP>1</SP>. Fig. 20 shows an embodiment similar to that in Fig. 13, but with the gripping hands 1G, 1D operated by jacks 40G, 40D as in Fig. 19. At the moment of passage of the machine M it is essential that each element of the guide 9 should be held fixed. As shown in Fig. 22, each element may be associated with an armoured flexible conveyer 30. As illustrated in Fig. 23 (not shown), the elements may be attached to props (34). Fig. 24 shows an embodiment wherein the gripping hand has imprints 19 of trapezoidal isosceles prisms with two rollers 4, 4<SP>1</SP> in each imprint. Springs 28 are inserted between the rollers 4, 4<SP>1</SP> and springs 29 are inserted between the pairs of rollers. The direction of clamping is controlled by a pillar which may be set in position 20G, as shown, when the machine M (not shown) would be moved in the direction of the arrow F, or alternatively (compare Fig. 10) in position 20D (not shown) so that the machine M is moved in the opposite direction.