| 摘要 |
A curved band-shape pad holder (12) made of synthetic resin is attached to an inner peripheral surface of a lower portion of a first-step boom member (1) serving as an outer boom member. Pads (13) made of a different synthetic resin material from the pad holder (12) are fitted into a plurality of concave portions (16) provided on an upper surface of this pad holder (12). In the pad holder (12), bending grooves (14) are provided on the upper surface and auxiliary bending grooves (15) are provided on a lower surface in parts between the concave portions (16) as means for helping the bending into a curved shape. With this pad holder (12) placed along the inner peripheral surface of the first-step boom member (1), a position of the pad holder is fixed in the boom circumferential direction and in the length direction by holder fixing means (17,18,19), and attached; thereby the assembling workability and the fitting property of the pads relative to the outer boom member are improved.
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