Trench shoring machine

Claim 1

A TRENCH SHORING MACHINE COMPRISING A PAIR OF TELESCOPICALLY ASSOCIATED MEMBERS, EACH OF SAID MEMBERS BEING HOLLOW AND HAVING SIDE AND TOP WALLS, SAID WALLS BEING RIGID PLATES FOR ENGAGEMENT WITH EARTH FORMING A TRENCH AND PROTECTING THE SAME FROM CAVE-INS AND THE LIKE, ONE OF SAID MEMBERS BEING AN OUTER MEMBER AND BEING ADAPTED TO RECEIVE THE INNER MEMBER THEREIN IN A NESTED RELATIONSHIP, SAID MEMBERS HAVING OPPOSING WALL SURFACES, ONE OF SAID MEMBERS HAVING GUIDE CHANNELS AND THE OTHER MEMBER HAVING COOPERATING ELEMENTS RECEIVED IN SAID CHANNELS FOR GUIDED MOVEMENT THEREIN, SAID GUIDE CHANNELS AND COOPERATING ELEMENTS BEING ON SAID OPPOSING WALL SURFACES AND DISPOSED TO SUPPORT SAID INNER MEMBER BY SAID OUTER MEMBER, A PLURALITY OF POWER OPERATED CYLINDERS OPERATIVELY INTERCONNECTING SAID MEMBERS, AND CONTROL MEANS FOR SELECTIVELY SIMULTANEOUSLY AND INDIVIDUALLY EFFECTING OPERATION OF SAID CYLINDERS TO EFFECT RELATIVE MOVEMENT OF SAID MEMBERS TO AN EXTENDED RELATIONSHIP AND TO RETURN SAID MEMBERS TO THEIR NESTED RELATIONSHIP, SAID INNER MEMBER HAVING AN END WALL RIGIDLY JOINING SAID SIDE AND TOP WALLS THEREOF TO PROVIDE A BACK FILL, EARTH ENGAGING WALL WHEREBY UPON ENGAGEMENT BETWEEN SAID END WALL AND BACK FILL EARTH SUCH RELATIVE MOVEMENT CAN BE EFFECTED.