What device informs the automatic transmission about the vehicle's speed?

The governor is the device that informs the automatic transmission about the vehicle's speed. It plays a crucial role in adjusting the transmission's operation based on the vehicle's current speed, allowing for shifting patterns that optimize performance and efficiency. The governor helps regulate the flow of hydraulic fluid within the transmission, thereby controlling gear shifts. This is essential for ensuring that the engine operates within its optimal RPM range, allowing for smoother acceleration and deceleration.

While other devices mentioned, like the speedometer and throttle position sensor, provide important data regarding vehicle operation, they do not directly inform the transmission of speed in the same way the governor does. Understanding the role of the governor within the context of an automatic transmission helps clarify its importance in vehicle dynamics and performance.