Pivoting beam type hydraulic excavator - has jib derricking ram chambers connected to chambers of third ram between jib and arm

摘要

The hydraulically-operated excavator has a job derricked in a vertical plane by a first ram, and a bucket arm hinging on the jib under the action of a second ram. A third ram (18) is coupled between the jib (2) and the arm (8), and the chambers on the opposite sides of the piston in this ram cylinder are connected to those on opposite sides of the first ram piston (4).