What should you do to keep the stacker in the straight direction?

To maintain a stacker in a straight direction, using the knob on the steering wheel with your left hand provides better control and maneuverability. This technique allows the operator to steer the vehicle effectively, ensuring that the stacker travels in a straight line without veering off course. Steering with one hand can be particularly beneficial in situations requiring precise movements, as it allows for finer adjustments.

Using both hands on the steering wheel might seem intuitive for stability, but it can limit the operator's ability to make quick or precise corrections, particularly when the load is heavy or visibility is compromised. Adjusting the speed with the foot pedal is vital for safe operation, but it does not directly influence the direction of travel. Lastly, while rearview mirrors provide important visual feedback for overall awareness and safety, they do not assist in steering the stacker in the desired direction. Thus, using the knob with your left hand becomes the most effective method for keeping the stacker straight.