Demount tool assembly and methods for automated tire changer machine

A method of changing a tire on a wheel rim utilizing a tire changer machine including a base, a drive assembly coupled to the base and configured to rotate a wheel rim and associated tire about a rotational axis, a support tower extending in spaced relation to the drive assembly, and a tool assembly coupled to the support tower,

• wherein the tool assembly includes a support, a demount tool coupled to the support and having a proximal end and a distal end, a pivot arm connecting the tool support and the demount tool, and a linkage connecting a resilient member between the tool support and a pivot point on the demount tool located between the proximal end and distal end, the method comprising:
• locating the support in a demount position relative to the wheel rim;
• and
• while maintaining the support in a stationary position, moving the demount tool along a predetermined path of motion in a tire demount procedure;
• whereby, as the demount tool is moved, the pivot arm constrains a proximal end of the demount tool to the predetermined path of motion while the linkage provides a limited freedom of movement of the distal end of the demount tool from the predetermined path of motion.

A method of changing a tire on a wheel rim utilizing a tire changer machine, the machine including a base, a drive assembly coupled to the base and configured to rotate a wheel rim and associated tire about a rotational axis, a support tower extending in spaced relation to the drive assembly, and a tool assembly coupled to the support tower,

• wherein the tool assembly includes a pivot arm, a support, a demount tool coupled to the support, and a guide element connecting the support and the demount tool,
• wherein the guide element includes a first link and a second link coupled to one another at a common pivot point,
• wherein the pivot arm is connected to the common pivot point, and a bias element spans a distance between the pivot arm and the common pivot point;
• the method comprising:
• locating the support in a demount position relative to the wheel rim;
• while maintaining the support in a stationary position, moving the demount tool along a predetermined path of motion in a tire demount procedure;
• whereby, as the demount tool is moved, the guide element provides a limited freedom of movement of the distal end of the demount tool from the predetermined path of motion;
• and
• resiliently loading the bias element to adjust the distance between the pivot arm and the common pivot point as the demount tool is moved along the predetermined path, whereby the loading of the bias element directs the demount tool to a position engaging a bead of the tire that otherwise could not be accommodated by the predetermined path.

A demount tool assembly for a tire changer machine comprising:

• a support;
• a demount tool coupled to the support and selectively positionable relative to the support, the demount tool having a proximal end and a distal end, the distal end configured to extract a bead of the tire from a wheel rim;
• and
• a guide element connected to the demount tool, the guide element comprising a linkage connecting a resilient member between the tool support and a pivot point located between the proximal end and distal end, wherein the guide element is configured to constrain movement of the proximal end to a predetermined path of motion and to provide a limited degree of freedom of the distal end from the predetermined path of motion in a tire demount procedure, thereby allowing the distal end to reliably grip the bead of the tire while the support is maintained in a stationary position relative to the wheel rim.