SERVO OIL PRESSURE CONTROL DEVICE FOR AUTOMATIC TRANSMISSION

摘要

PURPOSE:To prevent the occurrence of a shift shock owing to re-grasping of a brake during shift down of an automatic transmission. CONSTITUTION:A pressure regulating means 3 by which a servo oil pressure for engaging the friction engaging means of brakes B-2 and B-3, having a relation wherein the one thereof is released and the other thereof is engaged during a shift, with each other is controlled in a stepped manner through detection of input rotation and input torque is provided. The pressure regulating means 3 is controlled by an electronic control device 7 and performs low pressure waiting in which a servo pressure on the engagement side is maintained at a constant low pressure and regulation of a pressure through which slow and gradual boosting is effected at a given increase factor, and a rapid rotation change and tie up of a brake are prevented from occurring.