Center mechanism for tire building drum

A center mechanism for a tire building drum, the tire building drum being rotatably mounted on a central drive shaft and including a center portion, the center mechanism being disposed in the center portion of the drum, the center mechanism comprising:

• a hub seating on and being secured to the central drive shaft;
• a single axially-extending piston seating on and extending circumferentially about the hub;
• a cylinder being disposed about the piston and cooperating with the hub and the piston to form a pneumatic chamber;
• a plurality of links being operatively connected to the piston;
• and
• a plurality of segment bars being disposed about the circumference of the center mechanism, each one of the segment bars being operatively connected to selected links and seating between a lip of the cylinder and a distal end plate, whereby upon the introduction of compressed air into the pneumatic chamber, the piston moves in an axial direction, thereby actuating movement of the links which in turn actuate radial movement of the segment bars.