When "D" range is selected, the manual valve allows fluid at line pressure to be directed to the front clutch, which will remain applied in all forward gears.
Fluid in this circuit is also directed to the governor and to the 1-2 shift valve where it is blocked at a differential area.
A separate circuit from the manual valve directs line pressure to a differential area of the 2-3 shift valve and this is held in the downshifted or 2 position by a combination of the differential force and the spring force.
The 1-2 shift valve is in two sections. The shift valve itself is the lower section and this is held in its downmost position by a combination of the differential force and by the upper section plunger and spring.
In addition, as soon as the accelerator is depressed, throttle pressure will be directed to assist in holding the valves in the downshifted position and thus ensuring that their movement will be influenced by accelerator position.
The line pressure supplied to the governor will be re-regulated by the governor to governor pressure when the vehicle is in motion and this governor pressure will be directed to the large land areas at the bottom end of the 1-2 and 2-3 shift valves.
