| 摘要 |
<p>The present invention provides a planetary gear unit (20). The planetary gear unit (20) comprises a planet carrier (11) comprising a backplate (13) and being provided with planet shafts (14) distributed uniformly around the planet carrier's axis and extending through bores (28) in the backplate (13), each planet shaft (14) rotatably supporting a pair of planet gears (17, 18) by means of planet bearings (15,16), the planet gears (17, 18) being mounted between a ring gear (19) and a sun gear (21) for mutual interaction. The planetary gear unit (20) furthermore comprises a key (26) provided in a keyway (27) of the planet shaft (14) and extending to the backplate (13) for preventing the at least one planet shaft (14) from rotating around its own axis. According to the invention, the key (26) and keyway (27) are provided at a location such that, under conditions whereby the planet shaft (14) is prevented from rotating relatively to the backplate (13) through the working of friction, the key (26) is elastically displaced in such a way that there is no contact between the key (26) and the keyway (27) in the planet shaft, but not at a zone of highest stress of the bores (28) in the backplate (13). An advantage of a planetary gear unit (20) according to embodiments of the invention is that rotation of the planet shafts (14) relative to his bore in the planet carrier (11) is prevented. The invention results in a free of wear contact between planet shaft (14) and planet carrier (11), thereby allowing all degrees of freedom of the planet shaft (14) without disturbing the load distribution between the planet gears (17, 18) of a pair on one planet shaft (14) and without disturbing normal functioning of the planetary gear unit (20).</p> |
