Coal shearer with foremounted crusher roll - maximum and minimum flow pressure switches use valve to link or part pump and adjuster

摘要

Coal shearer as a conveyor guided machine has a foremounted crusher or sizer roll which rotates on an arm fitted with a two-way cylinder, the arm to one side of the main machine frame and used to carry the roll motor as in 2357559. When the roll is the down position, two pressure switches allocated to the adjusting cylinder space or feedline loaded by the roll in this position take effect, one switch responding to maximum and one to minimum fluid pressure. When the low pressure switch operates, a subordinate valve between pump and cylinder links these two for flow purposes. When the high pressure switch operates, however, the valve connects the cylinder space to the sump. For use in workings where there is a firedamp hazard, the valve should be actuated by a pressure medium controlled by a magnetic valve which in turn is operated by the pressure switches and enclosed in a pressure-proof pocket within the hydraulic haulage on the machine.