according to a preferred embodiment as shown in fig1 the apparatus has a plastic or metal casing 1 which is constructed in such a way that a mouthpiece 2 is formed which is bounded on each side by a case 3 . to the mouthpiece 2 is connected a suction channel 4 which is also formed by the casing 1 and said suction channel leads to a schematically represented vacuum source s , normally a suction fan . the suction fan s can be quite independent of the apparatus because it serves , for example , to replace the conventional suction part in large industrial dust exhausters . however , the apparatus can also be autonomous , in which case the suction fan and further accessories , particularly the dust bag , can be provided specifically for the apparatus to which they are connected . each cage 3 is open at the bottom and preferably has an approximately rectangular cross - section with downwardly projecting side plates 5 and 6 . at least one roller 7 is loosely mounted in each cage and the external diameter of the roller is somewhat less than the distance between the inner surfaces of the two side plates 5 and 6 . in this connection &# 34 ; loosely mounted &# 34 ; means that the roller can move radially within a defined area . when the apparatus is moved in the direction of arrow 8 , each roller is only guided by side plates 5 and 6 and normally rolls along the floor or ground . it should be noted that the rollers 7 have no bearing or supporting function . the distance of casing 1 from the floor is either determined by the chassis of the dust exhauster on which the apparatus is mounted or by special runners ( wheels ) 9 ( fig4 and 5 ) or slides . as shown in fig5 each runner is mounted on a shaft 90 fixed to casing 1 and is prevented from falling out by a snap ring 91 . to permit travel with maximum quietness it is covered with a tread ring 92 which is preferably made from rubber . if the suction fan s is now switched on a powerful vacuum is formed in suction channel 4 and at the opening 2a of suction mouthpiece 2 . this draws the loosely running rollers 7 against the inner side plates 6 of the cage and this also applies to the rear rollers in the travelling direction which would normally move away from side plate 6 when rolling . due to the two - sided engagement of the rollers on the side plates bounding suction channel 4 and mouthpiece 2 , the mouthpiece is effectively extended down to the floor or ground . the suction cross - section between the floor and opening 2a is in this way effectively reduced and consequently the air speed is considerably increased . as the apparatus is more particularly intended for uneven floors as well as for carpets , when such unevenness occurs or even between the carpet fibres the air flows at high speed into the space between the front and rear rollers in order to replace the air sucked up by the suction fan s . this after - flow of air leads to an intense suction action which can be so large that even larger pollutants beyond the reach of the apparatus can be held or even drawn against the front rollers before the said rollers pass over the same . it is to be noted that no air can flow over the tops of rollers 7 because the rollers engaging with side plate 6 prevent any such secondary flow which would only impair the suction action . as a result of the suction or wake the rollers are not only pressed against side plate 6 but also against the floor to be cleaned so that for this reason alone the suction cross - section between the rollers and floors is always regulated to a minimum . the air gap between the opening or lips 2a of suction mouthpiece 2 and the floor to be cleaned is therefore at least partly limited on two sides ( left and right in fig1 ) by the rollers 7 . exceptions to this are only formed by the longitudinal spacings between the individual rollers of a cage 3 , the gaps between a single or several rollers on the one hand and the floor on the other formed when the particular roller or rollers pass over a relatively large pollutant ( inclined roller in fig2 ) and naturally the two terminal cross - sections at right angles to the direction of travel . each terminal cross - section is limited by the rollers on both sides of the mouthpiece 2 by the said mouthpiece itself and by the floor ( lateral inflow of air ). due to the loose guidance of rollers 7 the limiting of the air gap remains unchanged even when the casing is inclined as shown in fig7 and 8 . the changes in the position of casing 1 relative to the floor can best be carried out with runners 9 so that a thus equipped apparatus is best suited to be guided manually by a suitable handle ( not shown ). in order to prevent the rollers 7 from falling out of the cage when the apparatus is lifted in each case one bar 10 is passed through the hollow inside of the corresponding roller fixed in removable manner to the cage wall perpendicular to the image plane . thus , on lifting the apparatus the rollers are suspended on these bars , whereby the latter can be removed in order to remove the rollers 7 from cages 3 . in the description up to now reference has only been made to a single roller per cage . however , preferably each cage contains several rollers 7 which in the case of a flat floor roll over the latter coaxially to one another , whereby the bar 10 passes through all the rollers . if , as shown in fig2 one of the rollers strikes an unevenness , it can be raised independently of the others so that briefly a somewhat larger air passage cross - section is formed which closes again immediately upon passing over the obstacle . the length of the rollers is random within certain limits . however , it is recommended neither to use too long nor too short rollers which are rings rather than rollers because in the latter case too many air gaps would form which disturb an orderly flow to the mouthpiece . for the same reason it is advantageous to place more rollers in one cage 3 then in the other , whereby naturally the length of the rollers also varies . this prevents the gap between the rollers from exactly facing one another which could also have a disadvantageous influence on the flow . fig3 shows a slightly modified embodiment of the apparatus . the modification comprises placing an abrasion - proof insert 11 on each of the outsides of suction mouthpiece 2 , that is within cages 3 near the lower ends of plates 6 . this pair of inserts 11 is sufficient . no such insert is necessary on the opposite side plates 5 of the cage because due to the powerful suction action the rollers are always engaged against side plates 6 . this includes the rear rollers as can be gathered particularly clearly from fig9 to 11 which illustrate the operation of the apparatus . as can be seen , when the apparatus during its movement strikes against larger particles ( fig9 ) they are normally no longer pushed away as is the case with the known suction nozzles which have rubber lips . instead the roller 7 ( or one of the rollers with reference fig2 ) rolls over the obstacle ( fig1 ) whereby the roller is pressed somewhat more deeply into cage 3 . furthermore , according to fig2 it will also generally tilt with respect to horizontal . due to this raising action a larger air passage cross - section is temporarily formed which , however , if the suction fan and suction channel 4 are correctly dimensioned , is still too small to cause a serious drop in the flow rate in the area of mouthpiece 2 . the strong air flow carries with it not only small particles but when the larger particles have been released by the roller rolling over them , also the said larger particles ( fig1 ). then all the rollers are located on the floor again . as already stated , no air can be sucked over the top of the rollers . thus , the air must flow through the already mentioned gaps and spaces in the apparatus . as shown in fig6 these can also be spaces formed between individual rollers and the uneven ground , whereby grooves r in the floor also form such spaces . as can be seen in fig2 here again each roller can within certain limits move relative to the others . in the case of rough or uneven ground strong air flows occur on the bottom of the rollers which result in a corresponding cleansing action , whereby these air flows are parallel to the direction of movement . when the ground is smooth and flat without any depressions , there are no such air flows so that the air can only flow in from the side which in certain circumstances can lead to too small a passage cross - section and therefore to considerable suction noise . in the case of a smooth ground surface of this type such as occurs at airports , the apparatus can however be raised to such an extent that at least the front rollers in the direction of travel are raised somewhat from the ground and are only suspended on bar 10 . however , even in this case the rollers are not superfluous because when they encounter material to be sucked up which is higher than the distance between these rollers and the ground , they individually are raised and roll over the material so that the latter is not pushed away but instead comes into the area of suction mouthpiece 2 . the raising and therefore the setting of a given distance between rollers and ground can , in the case of travelling cleansing machines , be set , for example , from the driver &# 39 ; s seat . due to the sliding friction of the rollers 7 on side plates 6 there is also a self - cleaning action which ensures that the rollers always remain clean . it is only in the case of particularly strongly adhering , for example sticky , pollutants that these may have to be removed manually after using the apparatus . fig1 shows a somewhat simpler embodiment which is especially suitable when the apparatus only has to be moved in one direction , for example when fitted on a travelling cleansing machine . the direction of movement is again indicated by arrow 8 . in this embodiment only a single cage 3 with one or more rollers 7 is provided . on the other side of the suction mouthpiece 2 is provided a rubber lip 12 which is , for example , pressed strongly against the wall of mouthpiece 2 by a wing nut 13 or the like and a plate 14 . with the nut loosened the rubber lip can be set to the correct spacing from the ground . the front rollers function in the manner shown in fig9 to 11 . even material with large dimensions is sucked up by the suction fan before the rubber lip 12 reaches it . the engagement of rollers 7 on side plates 6 on mouthpiece 2 makes it possible to partly or even completely , as in fig1 , eliminate the cage if there is a sufficiently large suction pressure . in the latter case the rollers of each row are only loosely connected with the suction mouthpiece or the suction channel 4 by the particular bar 10 . when the suction fan is switched on they engage with the mouthpiece 2 whereby on the latter they slidingly roll on the ground . the insert 11 shown in fig3 can also be used for the loose guidance of rollers 7 when it is ensured that the distance from its edge 11a engaging with the roller to the opposite side plate 5 is smaller than the diameter of the roller or rollers ( fig1 ). on raising the apparatus the latter cannot fall from the cage . they are assembled by a lateral insertion into the cage ( perpendicular to the image plane ) whereby the cage must have a corresponding assembly opening which can be closed again after insertion has taken place . as bar 10 is unnecessary , rollers with a solid cross - section can be used here . however , in this case the height of the suction mouthpiece 2 above the ground or floor , the roller diameter , as well as the above - mentioned distance must be more accurately matched to one another than in the other embodiments . for this purpose side plate 5 can be provided with a projecting edge 5a which together with the edge 11a of insert 11 ( or a corresponding construction of side plate 6 ) fixes the said spacing in such a way that it is smaller than the roller diameter by the desired amount . the invention is not limited to the embodiments described and represented hereinbefore and various modifications may occur to those skilled in the art which are within the scope of the invention .
vacuum apparatus for sucking up pollutants with a suction mouthpiece maintained at a given distance above the ground . the mouthpiece is partially defined at least on one side by rollers guided loosely on the apparatus and held in place during operation by the vacuum created in the apparatus . the rollers enable the apparatus to operate effectively over rough ground and to pick up relatively large pollutants .