| 摘要 |
A new chain harrow of improved performance with regard to effective harrowing and non-clogging is made up of V-shaped elements (as seen in plan) interlinked with the apex of one connected to the end of a respective arm of a more forward element. The elements are formed of unusually large diameter steel rod (e.g. about 16 mm instead of the prior thickness of about 11 mm) with relatively unusually large loops and with a horizontal apex loop that is an incomplete turn of about 270 degrees so as to provide for a specially effective sweeping and guiding action. Each arm is provided at its end with a respective tooth at the end of a respective vertical loop for interlinking with the horizontal loop of the forward element. These loops are all of at least about 5 cm radius; the longer arm terminates in a trailing tooth with a trailing angle of about 15 degrees to the vertical to provide for normal harrowing, while the shorter arm also terminates in a trailing tooth with an angle of about 45 degrees to the vertical so as to be more self-cleaning when that is required. The two arms are of different lengths so that the teeth of successive elements follow transversely-spaced paths. The two teeth point in opposite directions so that the harrow is double-sided with different tooth actions for the two sides. Such a harrow not only is more robust but avoids the difficulties experienced with prior harrows of "rear-end curl" at the speeds at which harrows are now employed.
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