Vacuum lift device

摘要

A vacuum lift device comprising a lift tube which is able to contract and expand in an upward and downward direction, and a lift tube expansion control valve controlling the opening areas of the atmospheric openings of the lift tube. A hovering control valve controlling the flow area between the second atmospheric opening and the interior of the lift tube is provided. The lift tube expansion control valve is normally positioned at a position such that is completely covers the first atmospheric opening, and the second atmospheric opening is open to the outside space. At this time, the level of vacuum in the lift tube is adjusted by the hovering control valve so that an object to be lifted is maintained at a desired height.