Patent ID: 7985153

Claim:
A hydraulic control system of an 8-speed automatic transmission for vehicles, wherein a first clutch is operated at first, second, third, and fourth forward speeds, a second clutch is operated at a sixth forward speed, a third clutch is operated at fourth, fifth, sixth, seventh, and eighth forward speeds, a fourth clutch is operated at the third and fifth forward speeds and a reverse speed, a first brake is operated at the eighth forward speed and the reverse speed, and a second brake is operated at the second and seventh forward speeds, comprising: a first clutch/second clutch control portion controlled by a first proportional control solenoid valve and selectively supplying hydraulic pressure of a first pressure control valve to the first clutch or the second clutch; a third clutch control portion controlled by a second proportional control solenoid valve and supplying hydraulic pressure of a second pressure control valve to the third clutch as operating hydraulic pressure of the third clutch; a fourth clutch/first brake control portion controlled by a third proportional control solenoid valve and selectively supplying hydraulic pressure of a third pressure control valve to the fourth clutch or the first brake, the fourth clutch/first brake control portion supplying reverse range pressure to the first brake at the reverse speed; and a second brake control portion controlled by a fourth proportional control solenoid valve and directly supplying hydraulic pressure of a fourth pressure control valve to the second brake.