Items marked by the "RayTech" tag:

The valve body is a hydraulic “controller” (also called as a “transmission brain”) consisting of valves, solenoids, sensors batteries and attached to them are passages and channels, which guide the flow of ATF to various valves with the purpose to activate required clutch and shift the gear properly according to the driving situation.

While manual gearboxes utilize the clutch to shift speeds, automatic transmissions make use of a sophisticated hydraulic system for shifting, and the transmission solenoid is especially important for this process.