What should be ensured about the center wheel during calibration?

During the calibration of the center wheel, it is important that the wheel is able to move freely up and down. This mobility ensures that the wheel can properly reflect the changes in elevation and adjustment required for accurate calibration. Free movement allows for precise measurement and adjustments necessary for achieving correct paving thickness and flatness, which are critical for the performance of the paved surface.

Ensuring that the wheel moves freely up and down facilitates the evaluation of the proper interaction between the machine and the pavement, thereby supporting effective compaction and paving operations. If the wheel were to remain stationary or always elevated, it would prevent the necessary testing procedures from taking place, potentially compromising the accuracy of the calibration process. Weighting the wheel down would similarly restrict its intended function and could lead to inaccurate calibration results.