| 摘要 |
PROBLEM TO BE SOLVED: To arrange a spring seat by avoiding interference with another member, while improving durability of a frictional engaging piston provided with arranging holes for a return spring. SOLUTION: The piston 22 is provided with a partial cutoff area D having a lacking part 36a for avoiding interference with a counter driven gear. The durability of the piston 22 can be improved by enhancing the crack preventive effect of the piston 22 even if a base part 34 of the partial cutoff area D becomes thin by the arranging hole 50, by removing the arranging hole 50 from adjacent areas X1 and X2 and a central area Y in this partial cutoff area D. A bending part is formed in an area except for an area opposed to the partial cutoff area D of the piston 22 even by the spring seat. Thus, rigidity of the whole spring seat can be maintained, and interference with the counter driven gear is surely prevented by the presence of the lacking part of itself, to contribute to size reduction-weight reduction in an automatic transmission by reducing the size in the axial direction even when combined with the piston 22. COPYRIGHT: (C)2009,JPO&INPIT
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