Chuck with locking device

A chuck with locking device, comprising:

• a base body having a central longitudinal axis and being connectable for rotating with a drive shaft;
• an outer casing coupled outside said base body such that it can rotate coaxially but not move axially with respect to the base body, said outer casing having an axial opening;
• a plurality of jaws arranged movably with respect to the base body and the outer casing communicated with said axial opening;
• a fitting mechanism linking movements of the outer casing to movements of the jaws, such that rotation of the outer casing with respect to the base body in a tightening direction moves the jaws towards said central longitudinal axis and rotation of the outer casing with respect to the base body in an opposite loosening direction moves the jaws away from the central longitudinal axis;
• and
• a locking device comprising a ratchet mechanism operated by a locking control sleeve coupled outside the base body such that it can rotate between angular locking and release positions in cooperation with a cam and an elastic element, where said ratchet mechanism, when said locking control sleeve is in said angular locking position, blocks relative rotation between the base body and the outer casing in a loosening direction for loosening a grip of the jaws but allows relative rotation in a tightening direction for tightening the grip of the jaws, and when the locking control sleeve is in said angular release position, it allows relative rotation between the base body and the outer casing in both directions,
• characterized in that the ratchet mechanism comprises:
• a toothed ring that is fixed with respect to one of the outer casing and the base body, said toothed ring having a plurality of engagement teeth;
• one of a ratchet pawl and a plurality of ratchet teeth arranged such that the one of the ratchet pawl and the plurality of ratchet teeth are coupled with the toothed ring when the locking control sleeve is in the locking position and the one of the ratchet pawl and the plurality of ratchet teeth are separated from the toothed ring when the locking control sleeve is in the release position;
• a locking ring arranged outside the base body and fixed inside to the locking control sleeve in a position concentric with the toothed ring;
• said elastic element being a releasing elastic element arranged under compression between the locking ring and the outer casing;
• and
• said cam comprising a cam groove formed in a wall of the locking ring and a pin inserted in said cam groove and in a hole perpendicular to the central longitudinal axis formed in the base body, the cam determining axial movement of the locking ring between axial locking and release positions corresponding to the angular locking and release positions, respectively, when the locking ring is rotated by the locking control sleeve coaxially with respect to the base body;
• wherein the locking ring, when it is in said axial locking position, allows said ratchet pawl or teeth to engage the toothed ring with the locking position being in opposition to a force exerted by said releasing elastic element, and when it is in said axial release position, the locking ring allows said force exerted by the releasing elastic element to separate the ratchet pawl or teeth from the toothed ring.