A chuck having a locking device, comprising:
- a base body having a central axis and being connectable for rotating with a drive shaft;
- an outer casing axially fixed but rotatable about the central axis outside the base body, the outer casing having inner guides leading to an axial opening;
- a plurality of jaws movable along the inner guides;
- a fitting mechanism linking rotations of the outer casing with respect to the base body to movements of the jaws;
- and
- a locking device comprising a ratchet mechanism and an outer control sleeve operating the ratchet mechanism through an inner annular protrusion of a first diameter and through an inner annular recess of a second diameter bigger than the first diameter, the inner annular protrusion and the inner annular recess being provided in an inner surface of the control sleeve surrounding the ratchet mechanism and being adjacent to each other in the axial direction;
- wherein the ratchet mechanism comprises a toothed ring fixed to the base body, a pawl fixed to a lever pivotally mounted to the outer casing about a pivot pin parallel to the central axis, and an elastic element urging the pawl to engage the toothed ring;
- the control sleeve is connected to the base body through a cam configured to determine a simultaneous rotatably and axially slidably movement of the control sleeve relative to the base body between a releasing position, in which the inner annular protrusion of the control sleeve surrounds and interferes with the lever maintaining the pawn disengaged from the toothed ring against a force exerted by the elastic element, and a locking position, in which the inner annular recess of the control sleeve surrounds and does not interfere with the lever providing room enough to the lever for the engagement of the pawn with the toothed ring under the force exerted by the elastic element;
- and
- the ratchet mechanism is configured to block rotation of the outer casing with respect to the base body in the loosening direction but allowing relative rotation in the tightening direction when the control sleeve in the locking position and to allow relative rotation between the outer casing and the base body in both loosening and tightening directions when the control sleeve is in the releasing position;
- the axial position of the control sleeve providing an apparent visual indication of the configuration of the ratchet mechanism.