GB871971A - Thrust mechanism for advancing coal extracting machinery towards a coal face - Google Patents

Abstract

871,971. Hydraulic pushing-jacks. WILD & CO. Ltd., A. G. Oct. 12, 1959 [Sept. 2, 1958], No. 28100/58. Class 78 (3). [Also in Group XXIV] A pawl and rack for advancing a coal conveyer 23 to the coal face comprises a rack having side-plates 102, 103 provided with slots 22 which are engaged by reversible pawls 161, 16<SP>2</SP> pivotally mounted on a plate 13 which is connected to the end of a piston-rod 26 of a double-acting hydraulic ram 27 attached to the conveyer 23. The plate 13 is welded to the tops of sliding blocks 121, 122 which are adapted to slide longitudinally in the rack and are retained therein by rods 11<SP>1</SP>, 11<SP>2</SP>. The end of the piston-rod 26 is detachably secured to the plate 13 by means of a pivotally-mounted catch 20. The end of the rack remote from the conveyer 23 is secured to a block 24 on which is pivotally mounted one end of a staking member 25, the other end of which engages a fixed abutment 26, such as the roof of the coal mine. In use, the pawls 162 are engaged in slots 22 at the rear end of the rack, the piston-rod 26 being fully retracted, as shown in Fig. 6a. Forward movement of the conveyer 23 is effected by the supply of fluid to the cylinder 27, Fig. 6b. The piston-rod 26 is then retracted by fluid-pressure causing the pawls 16<SP>2</SP> to ride over the rack and engage slots 22 at the front end of the rack, Fig. 6c. Further forward movement of the conveyer is then effected by the hydraulic ram 27, Fig. 6d. The pawl is then reversed so that portions 16<SP>1</SP> engage slots 22 and the piston-rod 26 is retracted, Fig. 6e, extended and again retracted, Fig. 6f, in order to move the rack in the direction, of the conveyer in readiness for further forward movement of the conveyer.