OFFSET-BOOM CONSTRUCTION MACHINE.

摘要

An offset-boom construction machine, in which a stopper plate (13) as a safety device for a front working unit (30) is rotatably fixed to the front end bottom of a cylinder stay (5) with a pin (15) and is supported by an upper boom (4) at the rear end thereof so as to sway in association with the upper boom (4). The stopper plate (13) is in such a peripheral shape as comprising a first curved part (13a) to act as first stopping means and a second straight part (13b) to act as second stopping means. When a sway angle of the upper boom (4) is within a zone involving a risk of causing interference between the bucket (7) and the operator's cab (2) with an arm (6) fully dragged in, a side (6c) of the arm strikes said first curved part (13a) before occurrence of interference as above and mechanically prevents the arm from being dragged in further whereas, when the arm in a state where a sway angle of the upper boom is in a zone free of interference as above is dragged in and a dragged-in angle of the upper boom at this time is within a zone involving a risk of causing interference as above with the upper boom laterally swayed toward the operator's cab, the second part (13b) strikes a side (6d) of the arm before occurrence of said interference and mechanically prevents further sway of the upper room.