| 摘要 |
An improved boom-mounted jib unit ( 10 ) is provided having an increased range of motion and work envelope, which allows a user to lift heavier loads an otherwise work with less jib interference, as compared with prior jib units. The jib unit ( 10 ) includes a base ( 12 ) and a mounting component ( 28 ) permitting the unit ( 10 ) to be detachable secured to the upper end of a primary boom ( 22 ). The unit ( 10 ) also has a boom arm ( 14 ) made tip of upper and lower arms ( 16, 18 ). The arm ( 14 ) is articulated by a dual piston and cylinder assembly ( 20 ) having first and second piston and cylinder assemblies ( 84, 86 ) coupled between the base ( 12 ) and arm ( 14 ).
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