| 摘要 |
A coke-oven door, fitting within its frame with a predetermined vertical play, is extractable therefrom by an apparatus comprising vertically movable lifting elements on a horizontally displaceable support, the lifting elements being operable by a hydraulic cylinder with the aid of a controller responsive to the output of a pulse generator coupled with these elements. The controller includes a pulse counter which is stepped forward by the pulse generator after an initial upward motion (a) of the lifting elements from a lower limiting position, designed to fully engage these elements with coacting projections on the door, the lift being halted when a predetermined count has been reached to indicate a break-free level at which the door is substantially centered in its frame. The door is then horizontally withdrawn on the support and, when clear of the frame, is further elevated to a cleaning level at which the lifting elements have reached an upper limiting position. After cleaning, the door is lowered to the break-free level with backward stepping of the counter until it reaches again the predetermined count. Following reinsertion of the door into the frame, the lifting elements are lowered further to return the door to its initial position and to detach it from the apparatus.
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