| 摘要 |
A rotary switch, used to select the operating range of an automatic transmission, controls solenoid-operated valves corresponding to the selected range. The valves open and close a connection between a range valve and control pressure source. The range valve includes two spools having three positions. The spools are biased apart by a compression spring located between the spools. One valve position opens the fluid pressure source to a line that is pressurized to produce forward drive, a second position opens a connection between the fluid pressure source and a line that is pressurized to produce reverse drive, and a third position vents those lines to sump. The spring locates the spools at the third position. Control pressure force on opposite ends of each spool forces both spools to the first and second positions in response to the range selected by the vehicle operator.
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