| 摘要 |
According to a select shock attenuating method, line pressure, under which hydraulic fluid is supplied to hydraulically actuable and frictionally engageable coupling or couplings which are assigned to establish a gear ratio in an automatic transmission, is controlled. The automatic transmission has a plurality of selectable modes. In one mode, an appropriate one gear ratio state for a motor vehicle to start under normal road condition is established after placing a manual valve to a drive range position from a non-drive range position, while in another mode the automatic transmission is conditioned to another gear ratio. In the one mode, control signal on which the line pressure depends is subject to a pulse-like change with a first height corresponding to a first precharge level and a first duration corresponding to a first precharge period of time, then to a gradual increase at a first rate until a first coupling period of time is expired, and then to a drop to such a level as to keep the line pressure high enough to maintain torque transmission. In the another mode, the control signal is subject to a pulse-like change with a second height corresponding to a second precharge level and a second duration corresponding to a second precharge period of time, then to a gradual increase at a second rate until a second coupling period of time is expired, and then to a drop to such a level as to keep the line pressure high enough to maintain torque transmission.
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