Which of the following is NOT a mechanism for changing the direction of the stacker?

The speed gear lever is primarily utilized to adjust the speed of the stacker rather than to change its direction. While it is an essential component for controlling the movement speed of the vehicle—either to increase speed for faster movement or to decrease it for safer operation—it does not directly influence the steering or directional change of the stacker.

In contrast, the steering wheel is specifically designed for turning the stacker, allowing the operator to maneuver the vehicle around obstacles or reposition it as needed. The directional control lever serves the crucial function of indicating the forward or reverse movement of the stacker, meaning it directly governs the direction of travel. The turn signal is also relevant for indicating the direction of movement to other operators or pedestrians in the vicinity, thereby enhancing safety during operation.

Thus, understanding the function of each component highlights that the speed gear lever is not a mechanism used to change the direction of the stacker but rather to control its speed.