Patent ID: 9127442
Filing Date: 2015-09-08
Classification: E02F

Abstract:
1. A boom stick assembly for use on an excavating machine, comprising: a boom stick having a lower end, a top side, and an underside; a bucket secured to a lower end of the boom stick for pivotal movement relative thereto; a gripper pivotally connected to the lower end and underside of the boom stick for pivotal movement relative thereto; a breaker located inside the gripper and extending outward therefrom; the bucket being movable between an extended position and a retracted position to perform a digging operation; the gripper being movable between an extended position and a retracted position to perform a gripping operation in cooperation with the bucket; the gripper extendable and retractable to position the breaker in relationship to refusal material; the breaker being hydraulically operable to perform a breaking operation; a first hydraulic cylinder attached to a topside of the boom stick, and operable to control movement of the bucket independent of the breaker assembly; a second hydraulic cylinder attached to the underside of the boom stick, and operable to control movement of the gripper independent of the bucket; and, a relief valve and accumulator connected to the second hydraulic cylinder to permit compression of the second cylinder when the second cylinder is subjected to compressive force transferred from the first hydraulic cylinder that exceeds a limit of the relief valve.