Roof supports

Claim 1

A ROOF SUPPORT FOR USE IN MINES, COMPRISING A SERIES OF AT LEAST FIRST AND SECOND ROOF BEAMS OF WHICH A FIRST BEAM IS SLIDABLE FORWARDLY WHILE IN SUPPORTING CONTACT WITH THE ROOF, A FIRST PAIR OF EXTENSIBLE AND CONTRACTIBLE SUPPORT MEMBERS DISPOSED ONE AHEAD AND ONE BEHIND IN THE DIRECTION OF ADVANCE OF SAID BEAM, EACH PIVOTALLY ENGAGED AT ITS UPPER END WITH SAID FIRST BEAM, AND IN AN INITIAL SUPPORTING POSITION INCLINED DOWNWARDLY AND REARWARDLY FROM SAID FIRST BEAM TO CONTACT THE FLOOR AND TO UPHOLD SAID FIRST BEAM AND THE ROOF, A SECOND PAIR OF EXTENSIBLE AND CONTRACTIBLE SUPPORT MEMBERS EXTENDING BETWEEN SAID FIRST BEAM AND THE FLOOR, TO SUPPORT SAID FIRST BEAM WHEN THE FIRST PAIR OF SUPPORT MEMBERS IS CONTRACTED, MEANS REACTING BETWEEN SAID FIRST BEAM AND A TEMPORARILY FIXEDLY POSITIONED SECOND BEAM TO ADVANCE SAID FIRST BEAM, AND THEREBY TO ROCK SAID FIRST SUPPORT MEMBERS, WHILE EXTENDED IN THEIR SUPPORTING POSITION, RELATIVE TO THE FIRST BEAM AND TO THE FLOOR, INTO THEIR INITIAL SUPPORTING POSITION, ENERGY-STORING MEANS REACTING BETWEEN THE FIRST BEAM AND SAID FIRST SUPPORT MEMBERS, AND ENERGIZED BY SUCH ROCKING MOVEMENT OF THE FIRST SUPPORT MEMBERS INTO THEIR INITIAL SUPPORTING POSITION, TO SWING SAID FIRST SUPPORT MEMBERS INTO SUCH INITIAL SUPPORTING POSITION UPON THEIR CONTRACTION FROM CONTACT WITH THE FLOOR FOLLOWING AN ADVANCE OF THE FIRST BEAM, AND MEANS TO CONTRACT SAID SECOND SUPPORT MEMBERS FROM CONTACT WITH THE FLOOR PRIOR TO ADVANCE OF THE FIRST BEAM AND CONSEQUENT ROCKING OF THE FIRST SUPPORT MEMBERS.