Hydraulic control apparatus for continuously variable power transmitting system including reversing gear device and auxiliary transmission

摘要

A hydraulic control apparatus for a power transmitting system including a continuously variable transmission, a reversing device, and an auxiliary transmission, which apparatus includes: a solenoid valve for generating a pilot pressure for selectively placing the auxiliary transmission in high- and low-gear positions; high-gear and low-gear control valves normally operable based on the pilot pressure, to control high- and low-gear coupling devices of the auxiliary transmission to establish the high- and low-gear positions. The low-gear control valve is operated to engage the low-gear coupling device, when the low-gear control valve receives a pressure to be applied to the reversing device for forward run of the vehicle. The high-gear control valve may be operated to release the high-gear coupling device, when a thrust based on a pressure applied to the low-gear coupling device exceeds a predetermined value. The hydraulic control apparatus may further include a device for increasing a torque capacity of the high-gear coupling device during an engaging action thereof when a shift lever is operated to a reverse-drive position for reverse run of the vehicle.