| 摘要 |
An articulated joint for a foldable ladder includes an outer casing pair, an inner casing pair pivotally moving with respect to the outer casing pair, a lock device composed of a lock block and a locating pin. The locating pin has a ball end to be slightly squeezed in the locating hole such that the ball end is capable of retained in the locating hole and pivotally joined to the locating hole. The lock block provides triangular prism shaped projections at two opposite long edges of the bottom side of the lock block. Hence, the lock block can move along the guide slot of the outer casing shells steadily and be pivotally joined to fixing pin without loosening apart from each other.
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