GB843354A - Improvements in hydraulically operated supporting devices - Google Patents

Abstract

843,354. Mine roof supports. BOSCH G.m.b.H., R. Aug. 23, 1957 [Aug. 25, 1956], No. 26612/57. Class 20(2) [Also in Groups XXIX and XXX] A hydraulic pit prop comprises a ram 9 Fig. 1 sliding in a cylinder 10 having a pressure chamber 25 which receives hydraulic fluid from a pipe 15 and a valve comprising a closure member 38 to extend the prop, and a control chamber 32 containing a piston 34 responsive to hydraulic pressure to open the member 38 and release pressure fluid from the chamber 25 via a pipe 16 to collapse the prop. To set the prop, pressure fluid is pumped at 1 into the chamber 25 via the pipe 15 and bores 50, 51 and 52 in the head 18 of the ram 9 raising a spring loaded closure member 38. Fluid in an annular storage chamber 26 is concurrently forced into the chamber 25 via bores 53, 35, 36 and 52. A spring loaded core 44 acts as an excess pressure valve for the chamber 25. To remove the prop, a control mechanism 3 is actuated to force fluid through the pipe 16 to raise the piston 34, opening the member 38 and also connecting the bore 53 with the control chamber 32 so that fluid flows from the pressure chamber 25 to the outside via pipe 15 and to the storage chamber 26. The moving parts are lubricated by fluid entering a guide ring 19 via the bore 51 or through a slot (not shown between the guide ring and the inner wall of the cylinder. The guide ring 19 is made of synthetic material an( secured by a pin 20. Elastic sealing rings 22 are supported by abrasive resistant rings 23 having cross-sec tions of right angled triangles. In the embodiment of Fig. 2, the interior: of two telescoping members 54, 58 define one pressure chamber, a guide ring 59 around the lower end of the inner member 58 being held betweer a screw tapped ring 60 and a spring ring 61. To raise the prop, fluid from a pipe 7 enters the working chamber via an external control cylinder 7( containing a closure member 80. Tc collapse the prop, fluid is introducec via a pipe 8 to displace a piston 84 tc open the member 80 and release fluid from the prop yia the pipe 7. Ar excess pressure valve 86 is providec and an internal spring 66 assists ir the collapse of the prop.