Abstract: An expandable device for locking an annular member to a shaft for rotation therewith in which an annular body mounts on the shaft and carries a plurality of radially moveable bars overlying a single wall annular bladder lying against the surface of the body. The surface of the body is formed with annular raised ridges beneath each end of the bladder. A metal band formed with interlocking ends is secured around each end of the bladder to seal the ends of the bladder to the body.

Abstract: An expandable device for locking an annular core to a shaft for rotation therewith in which an annular body mounts on the shaft and carries a plurality of radially movable bars overlying a single-wall annular bladder lying against the surface of the body. The bars are positioned side by side around the circumference of the body and are interconnected by linking members to limit radial movement. An annular notched band is secured to the body of each end of the bars and engages recesses therein to transmit torque between the bars and the body. Pressurized air is introduced between the bladder and the surface of the body to force the bars radially outward to grip the core.