Abstract 1,022,469. Advancing mine roof supports. DOWTY MINING EQUIPMENT Ltd. Feb. 2, 1965 [Feb. 11, 1964], No. 5687/64. Heading F1P. An advanceable mine roof support 3, Fig. 2 (not shown) is released slowly by draining fluid through a line 19, an aperture 34 in a piston valve 26, a lever-actuated pilot valve 36 in parallel with valve 26 and through a line 22 leading to a main return line 23 and the prop is then released more quickly by the valve 26 being lifted from its seat 27 following the pressure drop across orifice 34 when the roof bar is clear of the mine roof the pressure drop across aperture 34 decreases which results in valve 26 closing and rate of release being slowed. If during advancement the roof bar re-engages the roof the resulting pressure build-up in valve chamber 29 lifts valve 26 to re-establish quick release of the prop. The pilot valve 36 is held open by a rod 39 when lifted by a lever 42 pivoted about its fulcrum by the rod 49 of a piston 47 subjected to main pressure supply from a line 12. The valve 36 is closed prior to resetting the prop by the lever being displaced by a record piston 52 when a valve 14 in a branch 13 of line 12 is opened by the conveyer advancing jack 5 at the end of its stroke.
IN A MINE ROOF SUPPORT HAVING A FLUID-PRESSURE-OPERATED PROP MEANS, A PAIR OF MEMBERS OPERABLE TO ENGAGE THE FLOOR AND THE ROOF OF THE MINE, RESPECTIVELY, WHEN THE PRESSURE IN THE PROP MEANS IS ELEVATED TO A GIVEN VALUE, AND A FLUID-PRESSURE-OPERATED JACK TO ADVANCE THE SUPPORT IN RELATION TO AN ANCHORAGE, THE IMPROVEMENT COMPRISING FIRST VALVE MEANS OPERABLE TO RELIEVE THE PRESSURE IN THE PROP MEANS AT A RELATIVELY SLOW RATE OF RELIEF, IN RESPONSE TO ACTUATION OF THE JACK IN A SUPPORT ADVANCING MANNER, AND SECOND VALVE MEANS OPERABLE RESPONSIVELY TO RELIEVE THE PRESSURE IN THE PROP MEANS AT A RELATIVELY HIGH RATE OF RELIEF, WHEN THE FIRST VALVE MEANS IS IN OPERATION AND THE PRESSURE IN THE PROP MEANS EXCEEDS THE VALUE BELOW THE GIVEN VALVE, AT WHICH THE SUPPORT WAS DISENGAGED FROM THE ROOF.
Claim 2
Dependent Claim
138 words
IN A MINE ROOF SUPPORT HAVING A FLUID-PRESSURE-OPERATED PROP MEANS, A PAIR OF MEMBERS OPERABLE TO ENGAGE THE FLOOR AND THE ROOF OF THE MINE, RESPECTIVELY, WHEN THE PRESSURE IN THE PROP MEANS IS ELEVATED TO A GIVEN VALUE, AND A FLUID-PRESSURE-OPERATED JACK TO ADVANCE THE SUPPORT IN RELATION TO AN ANCHORAGE, THE IMPROVEMENT COMPRISING FIRST VALVE MEANS OPERABLE TO RELIEVE THE PRESSURE IN THE PROP MEANS AT A RELATIVELY SLOW RATE OF RELIEF, IN RESPONSE TO ACTUATION OF THE JACK IN A SUPPORT ADVANCING MANNER, AND SECOND VALVE MEANS OPERABLE RESPONSIVELY TO RELIEVE THE PRESSURE IN THE PROP MEANS AT A RELATIVELY HIGH RATE OF RELIEF, WHEN THE FIRST VALVE MEANS IS IN OPERATION AND THE PRESSURE IN THE PROP MEANS EXCEEDS THE VALUE BELOW THE GIVEN VALVE, AT WHICH THE SUPPORT WAS DISENGAGED FROM THE ROOF.