| 摘要 |
PURPOSE: A 2-3/4-3 shift valve for a hydraulic control system is provided to improve the durability of an automatic transmission, and to reduce shift shock by restricting the stick of a valve with preventing leakage of line pressure. CONSTITUTION: Line pressure from a manual valve(1) corresponding to each range is supplied to a shift control unit(3), a pressure control unit(5) and a hydraulic distributing unit(7) to control friction factors including a front clutch, a rear clutch, an end clutch, a low reverse brake and a kickdown band brake. A valve spool(37) is installed in a bore, and hydraulic pressure is discharged corresponding to fluctuation of line pressure. Control pressure from the pressure control unit is prevented from leaking into the control passage with a line pressure discharge unit. Valve stick or leakage of line pressure is prevented by discharging the fluctuation of line pressure.
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