Attachment coupler for heavy machinery

An attachment coupler for heavy machinery, which is capable of detachably coupling an attachment to an arm of the heavy machinery, comprising:

• a coupler body configured to be coupled to the arm of the heavy machinery;
• a fixed hook configured to be formed on the coupler body and coupled to the attachment via a first coupling pin of the attachment which is inserted thereinto;
• a movable hook configured to be rotatably coupled to the coupler body via a hinge axis and coupled to the attachment via a second coupling pin which is inserted thereinto;
• a hydraulic cylinder configured to rotate the movable hook to be coupled to or disengaged from the second coupling pin;
• and
• a locking device configured to comprise a locking hook and an engagement device,
• wherein the locking hook is configured to be rotatably coupled to the coupler body via a hinge axis and close an open end of the fixed hook while being coupled to the first coupling pin;
• the engagement device is configured to rotate in association with the rotation of the movable hook to allow the locking hook to be coupled to or disengaged from the first coupling pin;
• and
• the engagement device is configured to prevent the locking hook from disengaging the first coupling pin while the movable hook is coupled to the second coupling pin;
• and
• wherein the engagement device comprises a link member, the link member comprises one end being coupled to the movable hook via a hinge axis and the other end being coupled to the locking hook via a hinge axis, and as the movable hook rotates in a direction of being coupled to the second coupling pin, the link member allows the locking hook to be coupled to the first coupling pin.