| 摘要 |
A restricting device is positioned in the flow duct leading from the main inlet to the cleaning head of a vacuum cleaner and is movable between a restrictive position, in which it serves to restrict the cross-section of the discharge outlet, and an open position, in which it restricts the cross-section of the discharge outlet to a lesser extent. The restricting device is movable by the passage of debris along the flow duct.
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