Abstract: A variable-vane assembly has a nozzle ring supporting an array of pivotable vanes, and a unison ring for pivoting the vanes in unison. A crank mechanism rotatably drives the unison ring, and includes an external crank assembly positioned radially outward of the unison ring, a non-round drive block disposed in a non-round recess in an outer periphery of the unison ring, and a crank arm having a forked end connected to the drive block and an opposite end connected to the external crank assembly. The forked end defines two legs and the drive block is disposed between the legs and is pivotally connected to the legs such that the drive block is pivotable relative to the crank arm about a pivot axis. The crank mechanism is arranged such that the crank arm is caused to swing through an arc of movement, thereby rotating the unison ring.

Abstract: A variable-vane assembly has a nozzle ring supporting an array of pivotable vanes, and a unison ring for pivoting the vanes in unison. A crank mechanism rotatably drives the unison ring, and includes an external crank assembly positioned radially outward of the unison ring, a non-round drive block disposed in a non-round recess in an outer periphery of the unison ring, and a crank arm having a forked end connected to the drive block and an opposite end connected to the external crank assembly. The forked end defines two legs and the drive block is disposed between the legs and is pivotally connected to the legs such that the drive block is pivotable relative to the crank arm about a pivot axis. The crank mechanism is arranged such that the crank arm is caused to swing through an arc of movement, thereby rotating the unison ring.