To control the dry dome of the coal mine hydraulic support and to achieve high-pressure liquid blockage in the working cavity of the dome, so that the metal structure of the support plays a supporting role; When switching the reading and switching, the domecrate of the other cavity into the liquid, at the same time opening the working cavity, the working cavity back liquid, the domecrate back compressed. Specifications Rated pressure: Rated flow rate 50 MPa: 80 l/min Interface flow rate: K J10, DN10 Material: medium carbon/stainless steel/1 Cr18Ni9