Abstract: In a tire changing machine, an apparatus is provided for controlling the stroke of the lower bead breaker shoe in breaking a tire bead from the bead seat of a wheel which includes a fluid motor and a pivot arm which cooperate to move the lower shoe from an initial position below and radially outwardly spaced from the wheel and tire, along a radially inward path to a position wherein the lower shoe engages the bead of a tire. A regulator assembly connected to the lower shoe prevents further radial inward, pivotal movement of the lower shoe once contact is made with the tire bead, and thereafter permits only upward movement of the lower shoe along a slight angle to the vertical so that it follows the profile of the wheel, without contacting the wheel, for completing the bead breaking operation.

Abstract: A drive assembly for sequentially driving two or more fluid motors which are adapted to rotate the centerpost shaft of a tire changing machine includes a spool valve controller supplied with operating fluid from a four-way valve. The spool valve controller comprises a valve spool rotatable within a valve body having axially spaced sets of ports which are interconnected by flow passages formed in the exterior wall of the valve spool. The spool valve controller is operable to direct operating fluid from the four-way valve to selected ports in the valve body, which, in turn, are connected with lines to the fluid motors. The operation of the spool valve controller is timed to operate the fluid motors in sequence so as to produce a continuous high torque output of the centerpost shaft with no dead spots. Rotation of the centerpost in both the clockwise and counterclockwise directions is controlled by the four-way valve.