Automatic transmission control system and method

In vehicle having a pump for providing a pressurized hydraulic fluid to an automatic transmission having a mechanical planetary gear train with gear shift elements actuable in response to the pressure of said hydraulic fluid, a method for controlling the pressure of said hydraulic fluid provided to said gear shift elements comprising the steps of:

• (a) providing said transmission with a control assembly comprising:
• a governor for deriving a pressure signal proportional to the speed of said vehicle;
• a cylindrical control valve movable along a longitudinal axis in response to said governor pressure signal to select control positions controlling the flow of said pressurized hydraulic fluid to said gear shift elements,
• a biasing member for normally biasing said variable control valve at a first select control position;
• and
• an adjustable position delimiter for maintaining said control valve at a second select control position effective for providing said hydraulic fluid to said gear shift elements at a pressure effective for actuating said gear shift elements at a preselect vehicle speed;
• (b) adjusting said position delimiter to maintain said control at said second select control position;
• and
• (c) deriving said governor pressure signal, whereby said control valve is moved from said first select control position to said second select control position in response to said governor pressure signal.