Six-speed powertrain and hydraulic control system for automatic transmission

A hydraulic control system, in which hydraulic pressure generated in an oil pump is controlled to a predetermined level, and part of this pressure is supplied as operational pressure to a damper clutch and to a reducing valve, and another part of this pressure is selectively supplied to a plurality of friction elements through a manual valve and a hydraulic control distribution assembly,

• wherein the manual valve is indexed with a driver-manipulated select lever and includes three conversion paths for a reverse R range, neutral N and park P ranges, and a drive D range,
• wherein in the hydraulic control distribution assembly, hydraulic pressure of a second pressure control valve generated by a first solenoid valve, which controls line pressure supplied from a pressure regulating valve, is supplied through a switch valve to a first brake in a first speed of the drive D range and the reverse R range via a first fail-safe valve, and to a fourth clutch through a third fail-safe valve in a fifth and sixth speed of the drive D range,
• wherein hydraulic pressure of the second pressure control valve generated by a second solenoid valve, which controls D range pressure supplied from the manual valve, is supplied as control pressure to the first fail-safe valve and a second brake operating in second, fourth, and sixth speeds of the drive D range through the second fail-safe valve,
• wherein hydraulic pressure of a third pressure control valve generated by a third solenoid valve, which controls the D range pressure supplied from the manual valve, is supplied as control pressure to the second fail-safe valve and a first clutch operating in first, second, third, and fifth speeds of the drive D range,
• wherein hydraulic pressure of a fourth pressure control valve generated by a fourth solenoid valve, which controls the D range pressure supplied from the manual valve, is supplied as control pressure to a second clutch operating in the third, fourth, fifth, and sixth speeds of the drive D range, and to the first fail-safe valve and the switch valve,
• wherein hydraulic pressure of a fifth pressure control valve generated by a fifth solenoid valve, which controls line pressure supplied from the pressure regulating valve, is supplied to a third fail-safe valve and a third brake operating in the neutral N range, the reverse R range, and in the first, second, third, and fourth speeds of the drive D range, and
• wherein reverse pressure from the manual valve when shifting into the reverse R range is supplied directly to the third clutch and simultaneously as control pressure to the second fail-safe valve.