An attachment module configured to attach a tool to a distal end of an excavator arm , the attachment module comprising: - an arm section comprising a first attachment arrangement (5', 5") for attaching the arm section to the distal end of the excavator arm , and - a tool section comprising a second attachment arrangement (6', 6") for attaching the tool to the tool section , wherein the tool section is rotatably arranged relative to the arm section around a rotation axis (Ra), and wherein the attachment module comprises a locking assembly controllable between - a locked state in which the locking assembly locks the tool section from rotating relative to the arm section around the rotation axis (Ra), and - an unlocked state in which the locking assembly unlocks the tool section from the arm section such that the tool section is free to rotate relative to the arm section around the rotation axis (Ra), wherein the locking assembly comprises a locking member and an actuator assembly operably connected to the locking member to move the locking member between a locking position, in which the locking assembly assumes the locked state, and an unlocking position, in which the locking assembly assumes the unlocked state, characterised by the locking assembly further comprising: - a first toothed section arranged on the arm section , - a second toothed section arranged on the tool section , and - a third toothed section arranged on the locking member , and wherein the third toothed section engages with both of the first and second toothed sections when the locking member is in the locking position and engages with only one of the first and second toothed sections when the locking member is in the unlocking position. - an arm section comprising a first attachment arrangement (5', 5") for attaching the arm section to the distal end of the excavator arm , and - a tool section comprising a second attachment arrangement (6', 6") for attaching the tool to the tool section , wherein the tool section is rotatably arranged relative to the arm section around a rotation axis (Ra), and wherein the attachment module comprises a locking assembly controllable between wherein the tool section is rotatably arranged relative to the arm section around a rotation axis (Ra), and wherein the attachment module comprises a locking assembly controllable between - a locked state in which the locking assembly locks the tool section from rotating relative to the arm section around the rotation axis (Ra), and - an unlocked state in which the locking assembly unlocks the tool section from the arm section such that the tool section is free to rotate relative to the arm section around the rotation axis (Ra), wherein the locking assembly comprises a locking member and an actuator assembly operably connected to the locking member to move the locking member between a locking position, in which the locking assembly assumes the locked state, and an unlocking position, in which the locking assembly assumes the unlocked state, characterised by the locking assembly further comprising: - a first toothed section arranged on the arm section , - a second toothed section arranged on the tool section , and - a third toothed section arranged on the locking member , and - a first toothed section arranged on the arm section , - a second toothed section arranged on the tool section , and - a third toothed section arranged on the locking member , and wherein the third toothed section engages with both of the first and second toothed sections when the locking member is in the locking position and engages with only one of the first and second toothed sections when the locking member is in the unlocking position. <EOS>