Travelling hydraulic development frame for mining operations

Claim 1

ADVANCING MINING PROP ARRANGEMENT COMPRISING A PAIR OF LONGITUDINAL RACKS ARRANGED SIDE BY SIDE, EACH RACK HAVING A FORWARD END AND A REARWARD END AND PIT PROP OVERHEAD BEARING MEANS SUPPORTED THEREON FOR ALTERNATE EXTENSION INTO AND RETRACTION FROM ENGAGEMENT WITH THE MINE CEILING, LONGITUDINALLY EXTENDING COACTING MOVING MEANS INCLUDING A FIRST MOVING PART AND A SECOND MOVING PART DISPOSED BETWEEN SAID RACKS, SAID PARTS BEING MOVABLE LONGITUDINALLY WITH RESPECT TO ONE ANOTHER YET BEING SECURED FROM TRANSVERSE AND ANGULAR MOVEMENT WITH RESPECT TO EACH OTHER, A FIRST ARM HINGEDLY ATTACHED ABOUT A LONGITUDINAL AXIS TO THE FORWARD END OF A FIRST OF THE LONGITUDINAL RACKS AND A SECOND ARM HINGEDLY ATTACHED ABOUT A LONGITUDINAL AXIS TO THE REARWARD END OF A SECOND OF THE LONGITUDINAL RACKS, A FIRST ANGULARLY ADJUSTABLE HORIZONTAL GUIDE BAR SECURED TO THE FORWARD END OF SAID SECOND RACK AND SLIDABLY ENGAGED BY SAID FIRST ARM AND A SECOND ANGULARLY ADJUSTABLE HORIZONTAL GUIDE BAR SECURED TO THE REARWARD END OF SAID FIRST RACK AND SLIDABLY ENGAGED BY SAID SECOND ARM, SAID FIRST MOVING PART BEING PIVOTALLY CONNECTED TO SAID FIRST ARM FOR MOVING SAID FIRST ARM AND IN TURN SAID FIRST RACK IN THE ANGULAR DIRECTION OF SAID FIRST GUIDE BAR AND SAID SECOND MOVING PART BEING PIVOTALLY CONNECTED TO SAID SECOND ARM FOR MOVING SAID SECOND ARM AND IN TURN SAID SECOND RACK IN THE ANGULAR DIRECTION OF SAID SECOND GUIDE BAR, FOR THE ALTERNATE ADVANCING OF THE RACKS BOTH ANGULARLY AND LONGITUDINALLY WITH RESPECT TO EACH OTHER.