| 摘要 |
The disclosure is directed to a grab bucket suspended from the cable of a hoisting means. The hosting means includes a first reversible motor drive means to raise and lower the grab bucket and a second motor drive means is associated with the grab bucket for opening and closing the bucket. Pursuant to the invention, a slack line limit switch is arranged and configured to detect a slackening condition in the cable as when the bucket reaches a pile of material. Upon said slackening condition, the limit switch operates to stop the first reversible motor drive means and to start the second reversible motor drive means to commence the closing of the bucket. Moreover, a timer relay means is also associated with the slack line limit switch and is operative after the detection of the slackening condition in the cable to time out after several predetermined periods to operate the first and second motor drive means in a preselected sequence, to raise the closing bucket somewhat above the pile, suspend the bucket above the pile until it is fully closed, and thereafter raise the bucket to a final destination position.
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