Machine chuck

摘要

A machine chuck (10) having a base (13) to be rotated about a longitudinal axis. Jaw members (20) move relative to the base (13) and radially with respect to the axis. A scroll member (18) is mounted on the base for angular movement relative thereto, which scroll member (18) engages the jaws (20) to cause the radial movement thereof. The base (13) has an annular passage which receives pistons (17) attached to the scroll member 18. Fluid under pressure delivered to the passage (16) causes angular movement of the pistons (17) and therefore scroll member (18) relative to the base (13). This angular movement causes radial movement of the jaw members (20).