GB726730A - Shifting means, especially for shifting face conveyors - Google Patents

Abstract

726,730. Pneumatic single stroke apparatus. BOTHE, F. April 29, 1953 [April 29, 1952], No. 11906/53. Class 8 (2). [Also in Groups XXIX and XXX] A fluid pressure jack which is stated to be suitable for use in conjunction with the feeding mechanisms of machine tools, but is described in connection with an apparatus for advancing a conveyer towards a coal face, comprises a pair of telescoping cylinders 1, 6 a piston 8 secured to cylinder 6, a piston 10 connected to cylinder 1 by a rod 11 and means for admitting fluid pressure to the working spaces 14,15. To extend rod 4, fluid, e.g. compressed air, is admitted to space 14 through a port 19 and is simultaneously communicated to space 15 through a duct 13 in rod 11, the fluid within the space 77 being exhausted through ports 16, 17 and the annular space between cylinders 1, 6. Retraction of rod 4 is effected by admitting fluid through port 16 and opening port 19 to atmosphere. In a modification, the duct 13 does not open into space 14 and fluid is applied direct to spaces 14, 15 through a valve (not shown) which applies fluid to either or both of ports 13a, 19. As shown in Fig. 2, the rod 4 is universally pivoted to a face conveyer 5, and the cylinder 2 is pivoted to a spring urged strut 2 which wedges against the mine roof when the conveyer is being advanced, but which slides along the roof to a new wedging position when the jack is retracted towards the conveyer.