GB453560A - Yieldable prop for mines - Google Patents

Abstract

453,560. Hydraulic shock - absorbers. FEHLEMANN, W., 7, Hochfeldstrasse, Duisburg, Germany. Feb. 24, 1936, No. 5470. Convention date, May 27, 1935. [Class 108 (iii)] [See also Group X] A telescopic pit. prop of the kind in which an inner member works as a piston in an outer member which con. tains a liquid, a spring-controlled valve being disposed in a passage which interconnects cham. bers in the outer member and inner member, has means in the passage which allows only drops of fluid to pass through it thus ensuring a slow collapse of the prop under pressure. The inner member 2 is provided with a piston head 9 which slides in a chamber 15 of the outer member 1, and the interconnecting passage 21-21<111> through the piston head and pressure head 12 is provided with enlargements 17, 18, 19, two of which, 17 and 19, are filled with hair felt soaked in boring grease, the density of which can be adjusted by screws 20, 23 respectively. The enlargement 18 is adapted to receive a perforated rubber piece to serve as a valve between the piston head 9 and pressure head 12, which are capable of relative longitudinal movement under pressure. This relative movement is resisted by a spring 26, the pressure of which can be adjusted by a screwed rod 27 having a bushed sliding bearing 39, 41 in the inner prop member, the rod being rotated by means of an apertured disc 43. in order to allow escape of air from the chamber 16 of the inner member, a valve 50 is disposed in a chamber 47 communicating with the chamber 16, this valve being automatically opened as the head of the prop is brought to bear against the surface to be supported. A subsidiary light valve 53 prevents the entrance of dust when the prop is set. To set the prop, liquid is forced from a subsidiary chamber 33 by means of a piston 37 through a cock-controlled passage 35 communicating with the chamber 15 of the outer prop-member, the cock 36 being closed after the prop is set. For removal, the piston 37 is withdrawn and the cock opened so that liquid may flow from the chamber 15 through passages 32, 31, 30 to the chamber 16 of the inner propmember. The prop may be used alone or in conjunction with a concrete column. The liquid used in the prop is a solution of boring grease in water. A composition for boring grease is specified.