Tire building apparatus with segmented drum

Abstract

A tire building apparatus having a novel pneumatic actuator for radially moving a plurality of arcuate drum segments between an expanded, building position and a collapsed, removal position is disclosed. The pneumatic actuator comprises a piston fixedly mounted on a shaft and a reciprocally movable cylinder mounted on the piston. An annular primary chamber is defined around the shaft on one side of the piston by one end wall of the cylinder. The actuator also includes an annular pressure accumulating tank provided on the shaft on the other side of the piston. An annular secondary chamber is defined around the tank by the other end wall of the cylinder. The secondary chamber is in communication with the pressure accumulating tank through an opening built in the tank. A check valve is provided in the piston to permit air flow from the primary to secondary chamber. The cylinder is drivingly connected with the plurality of drum segments through mechanical links. Due to the difference in area of the inner wall defined by one and the other end walls of the cylinder, coupling the pressurized air to the actuator will cause the cylinder to move in a direction tending to expand the primary chamber while contracting the secondary chamber. A spacer of a predetermined axial length is provided to restrain cylinder movement further beyond a limit position corresponding to the building position of the segmented drum.