| 摘要 |
An arm (11) of a hydraulic excavator (1) is formed as a box-shaped structural body surrounded by left and right side plates (12, 13), an upper plate (14), a lower plate (15), and a thick rear plate (16). An upper end (16A) of the thick rear plate (16) is protruded upward from an outer surface (14A3) of the upper plate (14). Upper ends (22B) of a pair of arm cylinder brackets (22) joined to an outer surface (16C) of the thick rear plate (16) are arranged higher than the outer surface (14A3) of the rear thick upper plate (14A) and lower than the upper end (16A) of the thick rear plate (16). As a result, in each of the arm cylinder brackets (22), a joint area with the thick rear plate (16) can be ensured large, and joint strength can be improved. |
