"D" Position

SHIFT CONTROL "D" POSITION
In the D position, the 1-2 shift valve, 2-3 shift valve and 3-4 shift valve are moved up or down by pressure discharged from the governor valve which monitors vehicle speeds.
When the vehicle attains the specified speed, the 1-2 shift valve moves upward. Oil passage (1) is then opened to oil passage (2) to permit the flow of the band servo 2nd "apply" pressure (as a line pressure). As vehicle speed increases beyond the specified speed, the 2-3 shift valve moves upward. Oil passage (3) is then opened to oil passage (4) to permit the flow of both high clutch pressure and band servo 3rd "release" pressure (as a line pressure). As vehicle speed increases further, the 3-4 shift valve moves upward. Oil passage (5) is then opened to oil passage (6) to permit the flow of the band servo 4th "apply" pressure (as a line pressure).
In this way, the respective valves operate to provide automatic shifts from 1st, 2nd, 3rd, and then 4th 5 gears, and vice versa.