Permanent lining multiple jack system - has coupled roof bars with associated hydraulically operated mechanism to walk forward alternately

摘要

The permanent lining multiple jack systems are used in a mine. They have their roof bars coupled together and operated by hydraulic rams to walk alternately forward. Associated mechanism (2) is attached to the roof bars of adjoining support units I, II and operated hydraulically to vary the height of the bar (4). USE/ADVANTAGE - The support units in a mine move progressively in the roof support position.