Hydraulic control system for automatic transmission

A fluid control system for an automatic transmission for a vehicle comprising:

• first and second frictional elements operable to establish a reverse mode in the automatic transmission for allowing the vehicle to move backward when both the first and second frictional elements are actuated;
• a manual valve including first and second manual valve positions, the first manual valve position being to establish fluid communication between a pressure power source and a drive position pressure line when a selector lever is shifted to a drive position for establishing a drive mode allowing the vehicle to move forward, the second manual valve position being to establish fluid communication between the pressure power source and a reverse position pressure line when the selector lever is shifted to a reverse position for establishing the reverse mode;
• a first pressure control valve, connected between said first frictional element and the drive position pressure line, for providing a first preselected pressure level required for actuating said first frictional element in the drive mode;
• a second pressure control valve, connected between the second frictional element and the reverse position pressure line, for providing a second preselected pressure level required for actuating said second frictional element in the reverse mode;
• a fluid pressure line connected between the first frictional element and the reverse position pressure line and by-passing the second pressure control valve;
• a control unit, responsive to the selector lever shifting operation to the reverse position, to provide a control signal to said second pressure control valve for providing the second preselected pressure level to said second frictional element within a given period of time following the selector lever shifting operation;
• and
• pressure delay means communicating between the reverse position pressure line and the second frictional element for providing the second preselected pressure level to said second frictional element after said given period of time following the selector level shifting operation to the reverse position.