APPARATUS FOR AUTOMATICALLY MAINTAINING DESIRED PRESSURE IN SELF-ADVANCING ROOF SUPPORT PROPS AND FOR REGULATING PRELIMINARY LOAD CARRYING PRESSURE OF SUCH ROOF SUPPORT

摘要

A device for self maintenance of pressure in hydraulic props of powered roof supports and for adjustment of initial support pressure, distinctive in that it consists of two slidable two-way hydraulic manipulators connected in a series and mounted on a common block (25); the block is linked with an under-piston chamber (3) through the permanently open manipulator (2) which can be closed with liquid fed by pressure to a chamber (10) of a shifter (11); the liquid causes a roof support section to advance towards a longwall face; the device is also equipped with a check valve (18) placed between the prop controlling manipulator (16) (4) and the prop valve block (17); this valve checks the flow of liquid from the manipulator (16) to the prop block (17); situated perpendicular to the check valve is a permanently open manipulator (15) that can be closed by pressure of liquid from the pipeline (19) linking the manipulator (16) with the prop block (17); the liquid reaches the manipulator (15) through a throttle/check valve (20).IMAGE