Abstract: A fluid actuated chuck has two pairs of surfaces adaptable to engage a work piece with each of said pairs of surfaces being independently operable by the fluid. Such a chuck body includes means forming two pairs of surfaces carried and rotatably driven by the chuck body. Each of said surfaces of each of said pairs is free to move independently of the others. The chuck body also includes a pair of cylinders and passageways to deliver fluid thereto and carries a pair of pistons with one piston in each cylinder. Each of the pistons is free to move in the direction of the axis of rotation in response to fluid pressure within its cylinder. A first drive train forms a mechanical link between one of said pair of pistons and one of said pairs of surfaces, and a second drive train forms a mechanical link between the other of said pair of pistons and the other of said pairs of surfaces.