Hydraulisches Steuersystem für ein Automatikgetriebe

For achieving a high accuracy line pressure control and a high line pressure, a valve control system outputs a first signal pressure to a primary regulator valve as a second signal pressure when the first signal pressure is low. The valve control system outputs a gain pressure higher than the first signal pressure to the primary regulator valve as the second signal pressure when the first signal pressure is high. A change amount of the line pressure from the primary regulator valve concerning with a change amount of the first signal pressure is a gain. The gain is a low gain which increases the accuracy of the line pressure control when the first signal pressure is low, and the gain is a high gain with which the high line pressure is output when the first signal pressure is high.