| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To prevent damage to an automatic transmission by a simple structure if a drive force is reversely transmitted from the wheel side to the automatic transmission when an automobile is towed. <P>SOLUTION: A brake B1 capable of constraining one element of a planetary gear unit is provided with a main piston 16 and a sub-piston 24 which are operated under oil pressure from an oil pump 29. The main piston 16 is advanced under oil pressure from the oil pump 29 during normal running so as to engage the brake B1, thereby establishing a prescribed gear-shift stage in an automatic transmission. On that occasion, the sub-piston 24 is retreated under oil pressure from the oil pump 29, preventing interference with operation of the main piston 16. In a towed state that an engine is stopped and oil pressure from the oil pump 29 is eliminated, the sub-piston 24 is advanced by resilient force of an engaging spring 27 so as to engage the brake B1. Then, it is possible to prevent a specific member in the automatic transmission from being in an overspeed state. <P>COPYRIGHT: (C)2011,JPO&INPIT</p> |
