The invention relates to an operating system for an externally operated part of a closing unit, in particular for a mold carrier of a closing unit. During operation, the entire closing unit (12) moves in a predefined first direction (D) and the externally operated part (18) can be moved between at least two positions. The externally operated part (18) includes a guide element in the form of a cam roller (22) which is moveable for reaching at least one of the positions in a predefined second position (A) by at least one operating unit (29) arranged separately to the closing unit (12). The operating unit (29) includes at least one gripper member (48) which grabs the cam roller (22) for moving the part (18) to the predefined second position (A) and moves it in this direction. To minimize wear, the gripper member (48) includes two freely moveable guide rollers (50) arranged in parallel relationship at a particular spacing from one another and having axes in substantial parallel or tangential alignment to the first direction (D). The spacing between both guide rollers (50) corresponds essentially to the diameter of the cam roller (22) or is slightly greater than the diameter of the cam roller (22), and the cam roller (22) is able to move into this spacing for moving the externally to-be-operated part (18) in the predefined second position (A) and subsequently is able to move out of the spacing.