Patent ID: 6769468
Filing Date: 2004-08-03
Classification: B29D

Abstract:
A tire building drum having an axis, a center section and two end sections; wherein:each end section is provided with an expandable bead lock assembly having a plurality of axially extending, circumferentially spaced-apart finger segments adapted for gripping a bead such that each of the finger segments is expandable from a first finger radius in a collapsed condition of the bead lock assembly, to a second finger radius in a semi-expanded condition of the bead lock assembly, and to a third finger radius in a fully expanded condition of the bead lock assembly; each bead lock assembly comprises: a carrier ring; a plurality of radially expandable segments; and a plurality of elongate links extending between, and pivotably connected at respective ends to the carrier ring and radially inner ends of the expandable segments; wherein the finger segments are disposed at radially outer ends of the expandable segments; and wherein axial movement of the carrier ring causes radial movement of the expandable segments and the finger segments; and the tire building drum further comprises: a cylinder having a cylindrical piston portion; a first piston disposed in the piston portion; a second piston disposed in the piston portion axially between the first piston and the carrier ring; and at least one rod connecting the second piston to the carrier ring; wherein axial movement of the second piston causes axial movement of the carrier ring; and wherein axial movement of the first piston indirectly causes axial movement of the carrier ring only by axially pushing the second piston.