Rueckbarer hydraulischer Strebausbau

摘要

1,111,605. Hydraulic mine roof supports. GEWERKSCHAFT EISENHœTTE WESTFALIA. Jan.20, 1966 [Jan. 21, 1965; Feb.27, 1965], No.2640/66. Heading F1P. A walking hydraulic mine roof support is arranged to perform a movement cycle by a control unit having a clockwork time switch 54 which when set in operation automatically initiates e.g. electrically or hydraulically each individual movement within the movement cycle in the correct sequence and allows a sufficient time duration for normal completion of each individual movement. The clockwork time switch 54 can be set in operation from a remote position by a signal emitted by a portable wireless transmitter 46. The signal is detected by a receiver 45 which thereby operates to energize an electromagnet 50 which in turn causes an armature 50' to release a brake 51 and start the clockwork time switch. The time switch comprises a rotatable cylinder 55 having dogs 56-59 which sequentially operate pilot valves 64-67 controlling a servomotor 49 adapted to actuate slide valves in a control block 13 to direct pressure fluid in sequence through conduits 40-43 to cause the support to perform a movement cycle. The receiver 45 is arranged to detect a signal of predetermined frequency whereby supports having receivers set to different frequencies can be selected for operation by suitable adjustment of the signal frequency transmitted. Each roof support preferably comprises two frames each having two props and each being interconnected by a hydraulic cylinder operable to move one frame relative to the other. The time switch may comprise, Fig.1 (not shown) a pointer (16) held in a cocked position by a lever (34) releasable by a Bowden cable (30) and rotatable for a predetermined interval of time before it initiates the first individual movement by completing an electrical circuit through a contact (18). The contacts (18, 20, 22, 23, 25, 26) correspond, respectively, to relief of pressure in the first frame; advance of the first frame; re-setting of the first frame; relief of pressure in the second frame; advance of the second frame; and re-setting of the second frame. After the pointer has passed all its contacts it may be arranged to engage one end (32) of a cable (30) movable to release the cocking lever (34) associated with the time switch of another roof support in order to automatically initiate its movement cycle. In a modification a cable having dogs is movable so as to simultaneously operate the time switches of a plurality of supports spaced along the working face or alternatively each time switch in turn. A blocking device prevents further movement of the cable until the movement cycles have been completed.