Folding boom rotatable cranes

Claim 1

IN A BOOM COMPRISING A FIRST BOOM ARM PIVOTED TO A SUPPORT, A SECOND BOOM ARM PIVOTED TO SAID FIRST BOOM ARM, SAID SECOND BOOM ARM HAVING A FREE END ADAPTED TO ENGAGE AND LIFT A LOAD FIRST HYDRAULIC MOTOR MEANS ADAPTED TO MOVE SAID FIRST BOOM ARM VERTICALLY ABOUT ITS PIVOTAL CONNECTION WITH SAID SUPPORT, SECOND HYDRAULIC MOTOR MEANS ADAPTED TO MOVE SAID SECOND BOOM ARM IN A VERTICAL PLANE ABOUT ITS PIVOTAL CONNECTION WITH SAID FIRST BOOM ARM, AND A PUMP, SAID MOTORS BEING DIVIDED INTO FIRST AND SECOND FLUID CONTAINING CHAMBERS, SAID MOTORS BEING SO CONNECTED TO SAID BOOM THAT THE WEIGHT OF A LOAD TENDS TO REDUCE THE SIZE OF SAID FIRST CHAMBERS AND INCREASE THE SIZE OF SAID SECOND CHAMBERS; THE IMPROVEMENT COMPRISING HYDRAULIC CONTROL MEANS INCLUDING VALVES AND CONDUITS ADAPTED TO INTERCONNECT SAID HYDRAULIC MOTOR MEANS IN A SERIES HYDRAULIC CIRCUIT WITH SAID VALVES AND SAID PUMP IN AT LEAST ONE CONTROL POSITION WHEREIN EITHER SAID FIRST CHAMBERS OR SAID SECOND CHAMBERS ARE PLACED IN COMMUNICATION WITH EACH OTHER, WHEREBY THE PRESSURES CREATED IN ONE MOTOR BY A LOAD ARE USED TO BALANCE PRESSURES CREATED IN SAID OTHER MOTOR BY A LOAD.