Hydraulische Steuervorrichtung für ein Automatikgetriebe

摘要

Apparatus including a pressure regulating valve for regulating line pressure for hydraulically operated frictional coupling devices of a vehicle automatic transmission, and a cut-back valve for causing the pressure regulating valve to raise the line pressure to a higher level when the transmission is placed in first-speed position, than the normal level established when the transmission is placed in any higher-gear position whose speed reduction ratio is lower than that of the first-speed position. A pressure applying device is provided to apply to the cut-back valve first and second pressures to be applied to respective two coupling devices to establish a higher-gear position of the transmission, to operate the cut-back valve for causing the pressure regulating valve to raise the line pressure to the higher level when the vehicle is started in a high-gear start mode with the transmission placed in the higher-gear position.