Positioning device for a rotationally displaceable positioning element

A positioning device comprising:

• a positioning element that is rotationally displaceable about a first axis;
• a positioning member engaging with the positioning element, said positioning member being rotatable about a second axis that is substantially perpendicular to and spaced from the first axis;
• a slotted link disposed on the positioning element and arranged radially about the first axis;
• and
• a link block inserted into the slotted link such that the link block cannot be turned;
• wherein
• the positioning member is defined by a threaded spindle rotatable about a fixed point;
• a thread pitch of the threaded spindle corresponds to a predefined range of the positioning angle of the positioning element such that the positioning element is displaceable within the range of the positioning angle by two rotations of the threaded spindle or less;
• the positioning element includes a substantially circular shaped portion and the slotted link extends outward from the substantially circular shaped portion;
• the positioning element includes an elongated hole and a through hole provided in the substantially circular shaped portion, the elongated hole being concentric with the first axis;
• and
• the elongated hole and the through hole are arranged to periodically provide a fluid connection between a suction device and a vacuum generator.