Floor sweeper

Abstract

A floor sweeper, comprising travelling wheels installed on a housing whose bottom edge is equipped with a flexible seal member coming in sliding contact with the floor surface, a driving shaft with said wheels thereon and drivingly longitudinal follow-shafts disposed in front and rear thereof so that said follow-shafts rotate in opposite directions with the rotation of said driving shaft, main pulleys as respectively fixed on each follow-shaft, sub-pulleys as practically aligned with the respective main pulley by spacing along the direction of rotation of said main pulley, belt brushes as respectively stretched between the main pulley and sub-pulley, said belt brush consisting of a flexible belt-body and short bristles having a relatively weak resilience as densely set up on said belt-body, a cylindrical brush adjoining each said belt brush and equipped on each follow-shaft, said cylindrical brush consisting of a cylindrical body and plural rows of bristles having a relatively strong resilience as set up on the circumference of said cylindrical body by spacing said rows along the radial direction, and dust receivers disposed in the housing on the opposite sides of each brush.

Description

BACKGROUND OF THE INVENTION

The present invention relates to a floor sweeper which is suitable for sweeping off dust lying on a relatively flat floor such as a concrete floor, boarded floor, tiled floor and the like.

The conventional floor sweeper of this kind comprises a housing, a cylindrical brush rotatably supported within said housing about an axis perpendicular to the direction of travel of the housing, and dust receivers formed in front and in rear of said cylindrical brush, whereby dust is swept off into the front dust receiver by the cylindrical brush at the time of the forward movement of the housing while it is swept off into the rear dust receiver at the time of the backward movement of the housing.

However, such a known floor sweeper has been defective in that minute particles of dust swept up by the cylindrical brush are apt to fly out of the housing to cause environmental pollution.

With a view to overcoming such defects of the prior art, there has been developed an improved floor sweeper on which an application for patent has already been filed on Jan. 23, 1974 U.S. Ser. No. 435,680, also owned by the same assignee as the present invention said floor sweeper being characterized in that a flexible seal member devised to come in sliding contact with the floor surface is equipped on the bottom edge of the surrounding walls of the housing; a pair of belt brushes are disposed perpendicularly to the direction of movement of the floor sweeper, each of said belt brushes being stretched between a main pulley fixed on a front follow-shaft and a rear follow-shaft connected with a wheel shaft of the housing through an interlocking mechanism and a sub-pulley disposed by spacing along the transverse direction relative to the direction of rotation of said main pulley; and the tips of bristles set on the belt brush are to slide on the floor surface while moving toward the longitudinal center line of the housing with the forward and backward movement of the housing, whereby dust is swept up into a dust receiver formed on the opposite side of said center line.

This previously proposed floor sweeper is admittedly capable of overcoming the aforesaid defects of the conventional floor sweeper, but because the plural rows of bristles set up on the belt brush thereof are disposed, by spacing, perpendicularly to the direction of movement of the belt brush, dust lying on the portion of floor surface corresponding to the space between the adjoining two rows of bristles fails to be swept off completely at the time of sweeping, and the unswept dust is left in a stripe-pattern on the floor surface. Besides, a sizable dust such as cigarette butts is hard to sweep up by this floor sweeper.

SUMMARY OF THE INVENTION

A principal object of the present invention is to provide a floor sweeper capable of overcoming the aforesaid defects of the conventional floor sweepers.

Another object of the present invention is to provide a floor sweeper which comprises belt brushes disposed perpendicularly to the direction of movement of the housing and symmetrically relative to the longitudinal center line of the housing in front and in the rear of the housing, each of said belt brushes comprising a flexible endless belt and a multiplicity of bristles having a relatively weak resilience as densely set up on said endless belt and being so devised as to move toward said center line with the movement of the housing while making the tips of said bristles slide on the floor surface, thereby rendering it possible to sweep off throughly the relatively small-sized dust lying on the floor surface without sending it flying excessively or whirling up the powder dust to the outside of the housing.

A further object of the present invention is to provide a floor sweeper, which comprises a cylindrical brush adjoining the belt brushes as installed on the rotary shaft for rotating the belt brushes, said cylindrical brush consisting of a cylindrical body and plural rows of bristles having a relatively strong resilience as set up on the circumference of said cylindrical body by spacing said rows along the radial direction, whereby relatively sizable dust, such as cigarette butts, which strikes against the side edge of the belt brush but can not get in thereunder and is dragged thereby toward the dust receiver, is flipped up into the dust receiver by dint of a strong resilience of the row of bristles after being held in the space between the adjoining rows of bristles of said cylindrical brush and can be smoothly swept away from the floor surface.

A still further object of the present invention is to provide a floor sweeper, wherein the means for connecting the driving shaft with the follow-shaft comprises a gear train installed on the driving shaft and the follow-shaft to engage therewith and a one-way clutch for connecting the driving shaft with the gear installed thereon, whereby the bristles of each brush facing downward move toward the dust receiver while sliding on the floor surface at the time of movement of the housing in one direction but each brush never moves in the opposite direction even when the direction of movement of the housing changes, so that dust will be never swept away in the direction opposite to the dust receiver regardless of the direction of movement of the housing.

An additional object of the present invention is to provide a floor sweeper, wherein the wheel, driving shaft, follow-shaft and interconnecting means are installed on a supporting box, said supporting box being resiliently suspended from the top of the housing and disposed in about the center of the housing, whereby the wheels and each brush can be displaced vertically according to the undulation of the floor surface so that the wheel steadily rolls along the floor surface regardless of the undulation of the floor surface and the brush keeps on sliding on the floor surface, rendering it possible to perform a uniform sweeping of dust.

Yet another object of the present invention is to provide a floor sweeper, wherein the sub-pulley is pulled in the direction of straining the belt brush by means of a tension device equipped on the housing, whereby the belt brush is always strained to prevent the occurrence of a gap between the belt brush and the floor surface due to slacking of the belt brush so as to ensure the sweeping of dust.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a front view of the longitudinal section of the first apparatus embodying the present invention, which shows a cross-section along the line I--I in FIG. 2.

FIG. 2 is a cross-sectional view, as taken along the direction of arrow, of the apparatus shown in FIG. 1 upon cutting it along the line II--II.

FIG. 3 is a cross-sectional view, as taken along the direction of arrow, of the apparatus shown in FIG. 2 upon cutting it along the line III--III.

FIG. 4 is a plane figure illustrative of the inside, as uncovered, of the second apparatus embodying the present invention.

FIG. 5 is a cross-sectional view, as taken along the direction of arrow, of the apparatus shown in FIG. 4 upon cutting it along the line V--V.

FIG. 6 is a cross-sectional view, as taken along the direction of arrow, of the apparatus shown in FIG. 5 upon cutting it along the line VI--VI.

FIG. 7 is a cross-sectional view, as taken along the direction of arrow, of the apparatus shown in FIG. 6 upon cutting it along the line VII--VII.

FIG. 8 is a partial front view of the third apparatus embodying the present invention, which is illustrative of the arrangement of the supporting device as well as the guide plate member for the belt brush.

FIG. 9 is a partial front view of the apparaus shown in FIG. 8, which is illustrative of the roller member thereof.

DETAILED DESCRIPTION OF THE INVENTION

In FIGS. 1 - 3, the reference numeral 1 denotes the square housing whose contour consists of the top plate 24, the two side plates 25 and 25' and the front and rear plate 26 and 26'. At a prescribed distance from the front and rear plates 26 and 26' and in parallel therewith respectively, the transverse baffle plates 27 and 27' are perpendicularly suspended from the top plate 24. Two recesses enclosed by the front and rear plates 26 and 26' and the baffle plates 27 and 27' and having their bottom left open respectively accommodate the rollers 11 and 11' rotatably installed therein, and above each roller there is suspended the scraping plate 19 from the top plate 24. These rollers 11 and 11' are made of sponge rubber, and their bottom face projects below the level of the lower end of the housing 1.

At a prescribed distance from the baffle plates 27 and 27' and in parallel therewith respectively, there are suspended the transverse baffle plates 28 and 28', which are shorter than the baffle plates 27 and 27', from the top plate 24. In this case, one end each of the baffle plates 28 and 28' is fixed on the side plates 25 and 25', respectively, while the other end each of the baffle plates 28 and 28' is separated from the side plates 25 and 25', respectively. The longitudinal baffle plates 29 and 29' connected with the thus separated ends of the baffle plates 28 and 28' and parallel with the side plates 25 and 25' are suspended from the top plate 24.

By means of these tranverse baffle plates 27, 27', 28, 28' and longitudinal baffle plates 29, 29', a square recess 10 is formed in the center of the housing, and a dissymmetric pair of transversely L-shaped recesses adjoining this recess 10 are also formed.

The transverse recesses 13 and 13' parallel with the front and rear plates 26 and 26' for the L-shaped recesses have their bottom left open, and the longitudinal recesses 8 and 8' form the dust receiver equipped with the cover plates 14 and 14' which can be lifted at will.

About the center of both side plates 25 and 25' there is rotatably supported the driving shaft 3, and the wheels 2 and 2' are fixed on the two ends of the driving shaft 3, the bottom face of said wheels being practically on a level with the rollers 11 and 11' and projecting below the level of the lower end of the housing 1. The driving shaft 3 penetrates the baffle plates 29 and 29', and its portion located in the recess 10 is provided with the level gear 15 with the one-way clutch 12. The bottom of the recess 10 is closed with a cover plate.

The bevel gears 16 and 16' engaged with the level gear 15 are disposed on both sides of the driving shaft 3, and said gears 16 and 16' are fixed on the tip of the follow-shafts 18 and 18', respectively, said follow-shafts 18 and 18' being pivotally supported by the baffle plates 27, 28 and the baffle plates 27', 28', respectively.

The cylindrical brushes 5 and 5' are fixedly screwed on the portion of the shafts 18 and 18' located in the recesses 13 and 13', respectively and the main pulleys 20 and 20' are integrally fixed on one side of said cylindrical brushes 5 and 50', respectively. The sub-pulleys 23 and 23' are disposed parallel with the main pulleys 20 and 20' so as to be practically aligned with said main pulleys 20 and 20', respectively, by spacing along the direction of rotation of the main pulleys 20 and 20'. These sub-pulleys 23 and 23' are rotatably supported by one end of the bent shafts 22 and 22', respectively, whose opposite end is rotatably supported by the supporting members 21 and 21' fixed on the side plates 25 and 25'. The endless belt brushes 4 and 4' are respectively stretched between the pulleys 20 and 23 and between the pulleys 20' and 23'.

The cylindrical brushes 5 and 5' consist of a cylindrical body and plural rows of bristles 6 having a relatively strong resilience as set up on the circumference of said cylindrical body by spacing said rows along the radial direction. The belt brushes 4 and 4' consist of a flexible endless sheet 7 made of cloth, rubber and the like and a multiplicity of short, narrow leaf-shaped bristles 9 made of a soft synthetic resin such as nylon and having a relatively weak resilience as densely set up on the surface of said sheet 7. The bristle 9 is of such a length as will make its tip project below the level of the bottom face of the wheel 2, so that, at the time of operation, it is pressed against the floor surface to incline as shown in FIG. 3.

Both ends of the rollers 11 and 11' are conical. The bottom face of the housing 1 near the side plates 25 and 25' is equipped with the longitudinal belt-shaped resilient plates 31 and 31' made of rubber and the like which are slant to come in sliding contact with the surface of the conical portion of said rollers 11 and 11'. By virtue of the thus devised rollers 11 and 11', coupled with the resilient plates 31 and 31', there is no fear of the occurrence of a gap between the bottom edge of the surroundings of the housing 1 and the floor surface, and accordingly, dust swept up by each brush will never be sent flying to the outside of the housing 1. Besides, the front roller 11 works to flatten bulky articles such as paper scraps lying on the floor surface.

17 denotes the longitudinal guide plate installed on the base plate of the dust receivers 8 and 8', said guide plate being slant and slightly curved so as to bring the tip of each brush 4, 5, 4' and 5' in sliding contact therewith.

30 denotes the handle whose lower end loosely fits on the driving shaft 3 by its portion projecting from the housing 1.

When an apparatus having the above-described construction is pushed to advance by means of the handle 30 along a floor surface to be swept, with the rotation of the wheels 2 and 2', the gear 15 installed on the shaft 3 by means of the clutch 12 rotates, and the gears 16 and 16' engaged with said gear 15 rotate in opposite directions, to wit, in FIG. 2 the gear 16 rotates anticlockwise while the gear 16' rotates clockwise.

With the rotation of these gears 16 and 16', the cylindrical brushes 5 and 50' and the pulleys 20 and 20' also rotates by means of the shafts 18 and 18' in the same direction as the gears 16 and 16', respectively. Referring to FIG. 2, with the rotation of the pulleys 20 and 20', the bottom face of the belt brush 4 moves rightward while the bottom face of the belt brush 4' moves leftward; that is, both brushes 4 and 4' move toward the dust receivers 8 and 8', respectively, while the tip of the bristle 9 thereof slides on the floor surface.

Through the foregoing operation, dust passing under the bottom face of the roller 11 and entering the bottom of the housing 1 is swept up into the dust receivers 8 and 8'; that is, dust lying under the left portion of the apparatus in FIG. 2 is swept up by the brushes 4 and 5 while dust lying under the right portion thereof is swept up by the brushes 4' and 5'. To be precise, the relatively fine particles such as dust gets under the bottom face of the belt brushes 4 and 4' to be conveyed by the densely set bristles 9 along the direction of movement thereof and swept up into the dust receivers 8 and 8', while the relatively sizable trash such as a cigarette butt strikes against the side edge of the belt brushes 4 and 4' and is conveyed in the direction of movement of the belt brushes in the state of being dragged by said side edge without getting under the bottom face thereof to be swept up into the dust receivers 8 and 8' by means of the cylindrical brushes 5 and 5'.

In this case, as the bristles 9 of the belt brushes 4 and 4' are relatively weak in resilience and densely set up, they can convey dust gently toward the dust receivers 8 and 8' without sending it flying unnecessarily, while the bristles 6 of the belt brushes 5 and 5.dbd. are relatively strong in resilience and disposed by spacing regularly so that they can smoothly send a relatively sizable trash flying toward the dust receivers 8 and 8'.

When the apparatus is next made to retrocede by pulling the handle 30, inasmuch as the gear 15 is installed on the shaft 3 by means of the one-way clutch 12, even when the rotation of the shaft 13 is reversed, the gear 15 does not rotate and accordingly the brushes 4 and 5, 4' and 5' do not rotate, either.

Dust accumulated in the dust receivers 8 and 8' through the foregoing operation is discharged by lifting the cover plates 14 and 14'.

Next, shown in from FIG. 4 onward is the second embodiment of the present invention, and in the following will be given an explanation of this embodiment. In this connection, it goes without saying that there are many common features between the foregoing first embodiment and the present embodiment, so that detailed explanation hereunder will be centered on the features different from the first embodiment and the rest will be explained just briefly.

41 denotes the square housing. The cover 64 of said housing is shaped like an inverted square platter with skirts perpendicularly suspended from its surroundings. The lower end of the front skirt is fixed on the front frame 66 by means of the hinge 67 to be capable of opening and shutting. The bottom edge of each skirt is provided with the packing 68, said packing 68 mounting on the top faces of the front and rear frames 66 and 66' and the side frames 65 and 65' so as to seal the interstice between the cover 64 and each frame. The bottom of the housing 41 is left open, and inside said bottom there are installed the rollers 51 and 51' identical with the rollers 11 and 11' in the foregoing first embodiment, by disposing them to be adjoining the front and rear frames 66 and 66' and in parallel therewith. Above these rollers 51 and 51' there are suspended the scraping plates 78 and 78', respectively.

The supporting beam 69 is disposed along the longitudinal center line of the housing 41, and the perpendicular legs of said supporting beam 69 are fixed on the top face of the front and rear frames 66 and 66'. A pair of parallel links 46 and 46' are pivoted by one end each on the supporting beam 69, and the top of the supporting box 50 is pivotally connected to the other end of the links 46 and 46'. The supporting beam 69 and the top plate of the supporting box 50 are further interconnected by means of the adjusting bolt 49. Springs 47 are interposed between the beam 69 and the top plate of the supporting box 50 and constantly presses the supporting box 50 downward.

The driving shaft 43 is rotatably supported on the practical centers of both side plates of the supporting box 50. The outside extremities of the driving shaft 43 are provided with the wheels 42 and 42' fixed thereon, and the bevel gears 55 and 55' with the one-way clutches 52 and 52' are installed near the center of said shaft 43. The clutches 52 and 52' are so devised that either of the two can effectively works exclusively according to the forward and backward movement of the floor sweeper. For instance, at the time when the floor sweeper moves forward and the clutch 52 works to transmit the rotation of the driving shaft 43 to the gear 55, the clutch 52' does not work; on the contrary, at the time when the floor sweeper moves backward, the clutch 52' works exclusively.

The bevel gears 56 and 56' to engage with the gears 55 and 55', respectively, are disposed within the supporting box 50, and the follow-shafts 58 and 58' to support these bevel gears are rotatably supported by the cylindrical bearing equipped on the front and rear plate of the supporting box 50.

The fore ends of the shafts 58 and 58' are respectively provided with the cylindrical brushes 45 and 45' fixed thereon, and the main pulleys 60 and 60' are fixed on the body of said cylindrical brushes. The sub-pulleys 63 and 63' are disposed in parallel with the main pulleys 60 and 60' by spacing along the direction of rotation of the main pulleys 60 and 60', and these pulleys are rotatably supported on the supporting plates 62 and 62' projecting from the front and rear frames 66 and 66'. Between the pulleys 60 and 63 and between the pulleys 60' and 63' there are disposed the guide rollers 54 and 54', respectively, as rotatably supported on the supporting plates 53 and 53' projecting from the front and rear frames 66 and 66'. The endless belt brushes 44 and 44' are respectively applied to the set of pulleys 60, 63 and roller 54 and the set of pulleys 60', 63' and roller 54', and the rollers 54 and 54' function to prevent the floating-off of the brushes 44 and 44'.

The material and construction of the brushes 44, 44' and 45, 45' are identical with those of the brushes 4, 4' and 5, 5' in the foregoing first embodiment, saving that the present embodiment is different from the first embodiment in that the bristles of the brushes 45 and 45' are disposed along both sides of the brushes 44 and 44'. Further, in the present embodiment, the force end of the shafts 58 and 58' does not reach the front and rear frames 66 and 66', respectively, and forms a space among them, so that the brushes 44 and 44' can be simply replaced when damaged. Within the spaces among both side frames 65, 65' and the supporting beam 69 there are detachably installed the dust boxes 48 and 48'. The dust boxes 48 and 48' are provided with the dust inlet as equipped exclusively on the wall-plate facing the brushes 44, 45 and 44', 45'; the rest faces are surrounded by the respective wall-plate forming a cubic box. The upper part of the wall-plate of the dust boxes 48 and 48' on the side of the supporting beam 69 is provided with the pins 59 and 59', said pins 59 and 59' fit in the notch formed between each pair of clips 61 and 61' provided on both sides of the supporting beam 69. A pair of pins 72 and 72' project respectively from the portion of the front and rear wall of the dust boxes 48 and 48' near the side frames 65 and 65' of the housing 41, said pins 72 and 72' being respectively engaged with the supporting members 73 and 73' provided on both side frames 65 and 65'. The thus constructed dust boxes 48 and 48' are detachably installed within the housing 41 to see that the position of the base plate of said box be elevated from the floor surface by a prescribed distance. And, in the front dust box 48 there is installed the guide plate 79 for the purpose of augmenting the dust receiving capacity, said guide plate being curved from the front to the rear to protrude outward gradually and perpendicularly suspended from the top plate of the dust box 48, while on the base plate of the dust box 48' in the rear there is installed plural slanted plates 74 for the purpose of preventing dust from flowing backward to slip out through the inlet after sweeping.

57 denotes the guide plate installed aslant on the lower part of the supporting box 50 by means of the supporting plate 75, and the top edge of said guide plate 57 corresponds with the bottom edge of the dust inlet of the dust boxes 48 and 48', while the bottom edge thereof is provided with the belt-shaped resilient plate 76 consisting of urethane rubber and the like. The bottom edge of said resilient plate 76 is so devised as to come in sliding contact with the floor surface as well as the tip of brushes 44, 45 and 44', 45', whereby dust is not only smoothly led into the dust boxes 48 and 48' but also prevented from entering beneath the bottom of the dust boxes 48 and 48'.

The resilient plates 71 and 71' made of the same material and serving for the same purpose as that of the resilient plates 31 and 31' in the first embodiment are installed on the lower end of both side frames 65 and 65' of the housing 41 in the same way as in the first embodiment.

70 denotes the handle, which is pivotally connected, through the spring washer 77, to about the center of both side frames 65 and 65' of the housing 41 so as not to fall unnecessarily.

This apparatus as the second embodiment of the present invention is to perform sweeping as it is moved forward and backward on the floor surface by plying the handle 70 like in the foregoing first embodiment. In the present embodiment, however, inasmuch as the clutches 52 and 52' are to work as described above, each brush can be moved toward the dust box at all times during the forward and backward movement of the apparatus. Therefore, compared with the first embodiment capable of sweeping only at the time of either forward movement or backward movement, the present embodiment is superior.

Further, in the present embodiment, inasmuch as the supporting box 50 is suspended from the supporting beam 69 by means of the parallel links 46 and 46' and the spring 47 is interposed between the supporting box 50 and supporting beam 69, even when the floor surface has undulations, the supporting box 50 makes vertical motions according to said undulations without changing its horizontal position, so that the wheels 42 and 42' and each brush are automatically kept in contact with the floor surface, whereby not only the wheels can steadily roll over the floor surface but also the movement of each brush never changes with the condition of the floor surface. In this context, the degree of projection of the wheels 42 and 42' below the level of bottom face of the apparatus is adjusted by operating the adjusting bolt 49.

When dust has been accumulated within the dust boxes 48 and 48' as a result of the above operation, it is discharged by lifting the cover 64 and demounting the dust boxes 48 and 48' from the inside of the housing 41.

FIG. 8 and FIG. 9 are illustrative of only such features of the third embodiment as being different from the foregoing first and second embodiments. The sub-pulley 81 is rotatably supported by the arm 84 whose upper end is pivotally connected to the bracket 83 fixed on the side frame 82, and the tension spring 85 is stretched between the lower end of the arm 84 and the bracket 83. By virtue of such arrangement, the belt brush is constantly held at a fixed degree of tensity regardless of somewhat difference in length of the belt brushes.

To be precise, the hinge 90 with the spring 89 is fixed on the horizontal plate 88 of the supporting plate 87 installed on the lower part of the supporting box 86, the guide plate 91 is fixed on the upper slanted member of said hinge, and the bottom edge of the resilient plate 92 is devised to go up and down automatically according to the undulations of the floor surface so as to be always in sliding contact with the floor surface and prevent the occurrence of a gap between said bottom edge and the floor surface. The longitudinal reinforcing wire 93 is fixed on the resilient plate 92, and the front and rear ends of said wire 93 projecting beyond the resilient plate 92 is slanted upward. The provision of this reinforcing wire 93 has an effect that, even when the floor surface has a projecting part, as the wire 93 mounts said projecting part, the resilient plate 92 ascends along with the guide plate 91 in defiance of the pushing force of the spring 89 of the hinge 90 and climbs over the projecting part, thereby preventing occurrence of damages on the resilient plate 92 and the guide plate 91.

FIG. 9 is illustrative of an example of modification having rollers as transversely supported on the front and rear of the housing and relevant arrangement of supporting members therefor. To be precise, the roller 94 consists of the shaft 95 and the resilient tube 96 made of sponge rubber as fixed on said shaft 95, the two extremities of the roller 94 are provided with the hard rubber wheels 97 fixed thereon, the hollow conical cap 98 is fixed on the end of the wheel 97, the hollow shaft portion 99 projecting from the top of the cap 98 rotatably fits in the stud 101 projecting from the side frame 82, the conical surface of the cap 98 is held in sliding contact with the resilient plate 102 fixed on the lower part of the side frame 82 like other embodiments, and this portion is sealed. Further, between the bottom edge of the scraping plate 103 stretched between the slide frames 82 and the outer surface of the roller 94, there is formed a space, and this space is filled with the felt 104 fixed on the scraping plate 103. Accordingly, dust adhering to the surface of the roller 94 with the rotation thereof is entirely scraped off by the felt 104 and falls in the rear of the roller 94 to be swept away by the aforesaid brush.

Claims

What is claimed is:

1. A floor sweeper, comprising a housing defining a recess therein and whose bottom edge is equipped with a flexible seal member devised to be in sliding contact with the floor surface, wheels supporting said housing, said wheels being mounted on shaft means supported within the housing and defining an axis perpendicular to the direction of travel of the housing, a follow-shaft supported on each side of said axis and perpendicular to said axis, means for interconnecting said shaft means and the follow-shafts for rotating the follow-shafts in opposite directions upon rotation of said shaft means, a main pulley mounted on each follow-shaft, a sub-pulley spaced from each said main pulley and mounted for rotation in the same plane as said main pulley, a belt brush on each main pulley and stretched between each said main pulley and said aligned sub-pulley, dust receivers formed in the recess within the housing and positioned adjacent said belt brushes to receive floor sweepings from said belt brushes, each said belt brush including a flexible endless belt and a multiplicity of bristles having a relatively weak resilience as densely set up on said endless belt, and a cylindrical brush fixed on each follow-shaft so as to be adjoining a portion of the belt brush located on the main pulley, said cylindrical brush including a cylindrical body and plural rows of bristles having a relatively strong resilience as set up on the circumference of said cylindrical body by spacing said rows along the radial direction.

2. A floor sweeper according to claim 1, wherein said interconnecting means comprises a gear installed on the shaft means, gears installed on the follow-shafts, and a one-way clutch for connecting said shaft means with the gear installed thereon, whereby the tip of each brush is prevented from moving in a direction opposite to the dust receiver along the floor surface regardless of the direction of movement of the housing.

3. A floor sweeper according to claim 1, wherein said wheels, shaft means, follow-shafts and interconnecting means are installed on a supporting box, said supporting box being resiliently suspended from the top of said housing and disposed in about the center of the housing, whereby the wheels and each brush can be displaced vertically according to the undulations of the floor surface.

4. A floor sweeper according to claim 1, wherein said sub-pulleys are always pulled in the direction of straining the belt brush by means of a tension device equipped on the housing.