Safety control for cranes

Claim 1

SAFETY CONTROL MEANS FOR CRANES IN COMBINATION WITH A CRANE HAVING AN EXTENSIBLE AND VERTICALLY SWINGABLE BOOM, POWER MEANS TO EXTEND THE BOOM, SECOND POWER MEANS TO SWING THE BOOM VERTICALLY, AND MEANS AT HE OUTER END OF THE BOOM TO ENGAGE AND LIFT A LOAD, THE SAFETY CONTROL MEANS COMPRISING A FIRST MOVABLE MEMBER MOUNTED ON THE BOOM, MEANS RESPONSIVE TO EXTENSION OF THE BOOM TO ADJUST THE POSITION OF THE FIRST MOVABLE MEMBER, A CAM MOVABLY MOUNTED ON THE FIRST MOVABLE MEMBER, GRAVITY RESPONSIVE MEANS TO MAINTAIN THE CAM IN A PREDETERMINED POSITION RELATIVE TO VERTICAL, A SECOND MOVABLE CONTROL MEMBER, MEANS TO MAINTAIN THE SECOND CONTROL MEMBER IN ENGAGEMENT WITH THE CAM, A THIRD MOVABLE CONTROL MEMBER, MEANS RESPONSIVE TO THE LOAD ON THE BOOM TO MOVE THE THIRD CONTROL MEMBER TOWARD AND AWAY FROM THE SECOND CONTROL MEMBER, AND MEANS OPERATED BY ENGAGEMENT OF THE THIRD CONTROL MEMBER WITH THE SECOND CONTROL MEMBER TO PREVENT OPERATION OF THE POWER MEANS TO EXTEND OR ELEVATE THE BOOM.