[0009] Vacuum integrity of the plenum is automatically maintained during sweeping operations by the plurality of automatic flexible airflow operated flap valves which are influenced by vacuum (airflow) and urged to the closed position。 Subsequent to the sweeping operation and when cleaning of the filter mechanism is required, power to the fan is stopped, thereby influencing the vacuum integrity of the plenum causing the cessation of vacuum in the plenum and the areas or regions with which the vacuum communicates。 The filter shaker mechanism is then actuated at this time to expel dust and small debris from the filter mechanism which descends gravitationally to the region in the plenum just below the filter to pass through the flap valves which have been gravitationally opened due to the cessation of vacuum or airflow within the plenum。 The dust and debris passes through the open flap valves into the lower regions of the hopper。 The filter shaker mechanism includes an elongated cam which repeatedly causes gradual vertical upward move- ment of a rod encased in each of the lower folds of each filter to momentarily deform each filter fold followed by sudden cam disengagement to cause rapid downward movement of the rods, whereby the force of which causes vigorous snapping retensioning of the folds to expel dust particles therefrom。

[0010] According to one or more embodiments of the present invention, there is provided a street sweeper having dust control from two or more cleaning heads with one air source including a hopper, a plenum mounted in the upper region of the hopper, a fan mounted to the top of the plenum, a filter mechanism located at the upper region of the plenum in close proximity to and below the fan including fixed rods extending across the top of the plenum being captured by and extending through the upper region filter folds and positionable rods extending across the lower region of the plenum being captured by and extending through the lower region filter folds, cutouts in the lower region of the filter folds which expose a portion of each of the positionable rods, a filter shaker mechanism having a motorized cam extending perpendicularly to the positionable rods for con- tacting the exposed portion of each of the positionable rods, a plenum bottom having a plurality of orifices in an array, a plurality a flexible valves which align to the bottom of the

plurality of arrayed orifices, a duct extending downwardly from a lower inlet port at the plenum bottom and connecting to a gutter cleaning head surrounding opposing gutter broom assemblies, and inlet ports in the upper and rear portion of the plenum。 Other shown items which relate to the use of the present invention include a conveyor mechanism contained in a conveyor housing or conduit extending between the upper region of the hopper and a vacuumized chamber at the rear of a road sweeper truck, and a truck-mounted scissors jack which supports the hopper and contained plenum。

[0011] One significant aspect and feature of the present invention is a street sweeper having dust control from two or more cleaning heads with one air source。

[0012] Another significant aspect and feature of the present invention is a filter shaker mechanism which cleans a filter in a filter mechanism without removal of the filter from the sweeper truck。

[0013] Still another significant aspect and feature of the present invention is a plurality of fixed rods located in the upper region of the filter folds and a plurality of partially exposed positionable rods located and captured in the lower region of the filter folds。

[0014] Yet another significant aspect and feature of the present invention is a filter shaker mechanism having a cam which urges a plurality of partially exposed positionable rods captured in the lower region of the filter folds upwardly to cause upward distortion, displacement and distension of the filter folds followed by a sudden disengagement from intimate cam contact thereby allowing the filter folds to snappingly and jarringly return to the unactuated position to release and shed dust particles from the surfaces of the filter folds。 Such action is repeated until cleaning is complete。