| 摘要 |
PROBLEM TO BE SOLVED: To minimize the number of component and improve robustness in a six-speed transmission. SOLUTION: An electronic hydraulic control part 52 has three shift control valves. The shift valves are arranged in either one of a spring set position or a pressure set position for establishing flow passages in 5 friction devices for establishing 5 advance speed ratios and a reverse speed ratio. A pair of high rate control valves 62 and 64 control approaching friction devices, by increased pressure and a pair of low rate control valves 66 and 68 control separating friction devices by reduced pressure. The low rate valves 66 and 68 interrupts operations, in response to high rate control valve pressure, when the approaching friction devices have sufficient capacity for torque transmission. During a shift-down, a down shift valve prevents application of the high rate control valve pressure to a bias port. A discharge switch valve surely executes a shift-up or the shift-down in collaboration with a switching valve.
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