| 摘要 |
A crane has a rotatable body with a vertically pivotal boom connected thereto. An energy absorbing stop unit is mounted in a fixed position on the body, and a guide sleeve is pivotally mounted on the body adjacent the stop unit. A stop rod is pivotally connected to the boom at a point between the ends of the boom for vertical swinging movement, and the rod is maintained in the guide sleeve in every position of the boom. The guide sleeve is pivoted by the stop rod into alignment with the stop unit at the extreme upper position of the boom, and, at that position of the boom, the stop rod extends through the guide sleeve into engagement with the stop unit.
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