Control system for an automatic transmission

A control system for an automatic transmission comprising:

• a shift gear mechanism having a plurality of frictional elements including a low reverse brake, selectively actuated for switching a power transmitting path to establish a desired shift stage, and a hydraulic control circuit for controlling a hydraulic fluid for the frictional elements,
• an accumulator provided in a hydraulic passage communicated with the low reverse brake for obviating a shock as the low reverse brake is engaged, and
• back pressure control means for controlling a back pressure of the accumulator when a first stage is established in the shift gear mechanism through the engagement of the low reverse brake, the back pressure being controlled by a duty solenoid valve.

A control system for an automatic transmission comprising:

• a shift gear mechanism having a pluralityof frictional elements including a low reverse brake, selectively actuated for switching a power transmitting path to establish a desired shift stage, and a hydraulic control circuit for controlling a hydraulic fluid for the frictional elements,
• an accumulator provided in a hydraulic passage communicated with the low reverse brake for obviating a shock as the low reverse brake is engaged, and
• back pressure control means for controlling a back pressure of the accumulator when a first stage is established in the shift gear mechanism through the engagement of the low reverse brake, the back pressure being increased as vehicle speed is increased.