| 摘要 |
972,920. Agricultural implements. NATIONAL RESEARCH DEVELOPMENT CORPORATION. Aug. 9, 1963 [Aug. 10, 1962; Sept. 24, 1962; April 5, 1963], Nos. 30809/62, 36267/62 and 13734/63. Heading A1B. A tool bar 30 is supported in fornt of the front wheel axis of a tractor by a pair of interconnected side arms 31 pivoted at 34 to the side members 2 of a tractor, upward rotational movement of the tool bar about the pivotal axis being substantially unrestricted and downward movement being limited by a stop in the form of the front cross member 4 of the tractor. The tool bar is raised manually by means of lever 35 connected to a cross-member interconnecting arms 31 by a chain 37 passing over a pivotally mounted lever 38. An arm 42 rigidly secured to the tool bar carries a depth control wheel 46. In a modification the depth control wheel is omitted and a further tool bar provided behind the rear wheel axis of the tractor, both tool bars being lifted by the same lifting mechanism. In a further modification, the lifting mechanism is arranged to be actuated by the forward movement of the tractor. |
