| 摘要 |
An automatic transmission for a motor vehicle of the type having a mechanical planetary gear train with hydraulically actuatable gear shift elements has a gear select lever having a plurality of selectable forward drive positions, including automatic forward drive (D). A manual control valve, responsive to the position of the select lever, supplies a first pressurized hydraulic fluid to a selected gear shift element, e.g. a forward gear clutch, when the lever is in one of said forward drive positions. A control system which selectively interrupts the supply of fluid to the selected element comprises a main control valve, and a second fluid pressure acting on the main control valve to connect the supply of the first fluid to the gear shift element for engaging the element. A purging control valve vents the second fluid pressure supplied to the main control valve when the accelerator pedal is released, to discontinue the first fluid supply and exhaust the fluid from the gear shift element to disengage the element. A brake pedal position dependent control acts on the main control valve for permitting the gear shift element to disengage only when the brake pedal is depressed. |
