Condition for True Rolling
Condition for True Rolling True rolling occurs only when<the direction of motion of the vehicle is perpendicular to the wheel axis (Fig. 27.22A), i.e. the wheel is subjected to forward force. When wheel is subjected to side force that acts parallel to the wheel axis, a true scrub action is produced (Fig. 27.24B). When the wheel is subjected to both forward and side forces, the movement is compounded of true rolling and lateral distortion (Fig. 27.22C). This condition occurs when the wheels are being steered, i.e. the direction of motion is neither parallel nor perpendicular to the axis of rotation. On a circular path, true rolling condition occurs when the projected axes of several wheels all moving in different curved paths intersect at a single point called the instantaneous centre (Fig. 27.22D). When these projected axes do not intersect at a single point, a degree of tyre scrub results (Fig. 27.22E). Fig. 27.22. Road-wheel and tyre rolling conditions. A. True-rolling. B. True