US3318209A

US3318209A - Compactor

Info

Publication number: US3318209A
Application number: US414722A
Authority: US
Inventors: Eugene V Schultz
Original assignee: Individual
Current assignee: Individual
Priority date: 1964-11-30
Filing date: 1964-11-30
Publication date: 1967-05-09
Anticipated expiration: 1984-05-09

Description

May 1967 E. v. SCHULTZ 3,318,209

COMPACTOR Filed Nov. 30, 1964 2 Sheets-Sheet l v I ,I l

//v1/5/ /702 fI/Gf/VE 1/ 56/101 rz y 1967 E. v. SCHULTZ 3,318,209

COMPACTOR Filed NOV. 50, 1964 2 Sheets-Sheet B //Vl EN 70/? fl/Gf/VE KSCHUA r2 United States Patent C 3,318,209 CUMPACTOR Eugene V. Schultz, Fargo, N. Dak., assignor of one-half to Percy M. Schultz, Bismarck, N. Dak. Filed Nov. 30, 1964, Ser. No. 414,722 17 Claims. (Cl. 94-50) This invention relates in general to ground and road compacting, packing or tamping equipment, and more particularly to a novel self-cleaning, non-clogging compacting unit utilizing one or more gangs of individual compacting wheels, and a novel self-cleaning compaction wheel usable by itself or in a gang arrangement such as the one of this invention.

The compacting equipment of this invention is particularly directed towards heavy duty compacting equipment used in compacting earth or other material such as at road and building sites which is disturbed or loosely arranged to a considerable depth and which requires the application of large pressures and extremely heavy poundage per square inch of ground contact in order to compact the ground or material to the density required. The material being compacted is usually wet, because of the natural moisture content thereof or because of the addition of water thereto to attain plasticity thereof to aid in attaining the desired compacting results. This material has an adhesive, sticky, cloying quality which causes it to adhere to the compacting equipment. The heavy duty compactors presently available are so designed that the material not only adheres thereto initially, but progressively builds up thereon to a point where it materially interferes with the operation of the equipment and reduces the efficiency thereof, primarily by building up on the equipment to a point where the adhering material becomes load bearing, thereby substantially reducing the loading per square inch of ground contact and thereby materially reducing the force applied and the compaction efficiency of the equipment.

A typical illustration of the conventional equipment which becomes clogged readily with material are the well known compacting drums which have a plurality of radially extending tamping projections, teeth or feet mounted on the peripheral drum surface and disposed about the circumference thereof and which are commonly referred to as sheepsfoot rollers. In use if no cleaning device is provided, the material builds up on the drum periphery between the teeth and will eventually fill all of the space between the teeth out to the very ends of the teeth so that the adhering material and the teeth combine to provide a virtually continuous roller or drum surface and thereby materially reduces the amount of force applied per square inch to the ground to be compacted, thereby rendering the equipment virtually useless until cleaned.

In an effort to solve this problem, some of this equipment has been provided with a cleaning device such as a bar, pronged scrapers, shear blades, cables, etc., to clear adhering material from the compaction unit. These cleaning devices have not proved entirely satisfactory, are expensive, and furthermore wear out or fail quickly, requiring stoppage of the compaction operation for a relatively lengthy period of time in order to make the neces sary repairs or replacements.

Presently available equipment, if not provided with these cleaning devices, requires relatively frequent periodic shutdown of the equipment for cleaning thereof. These periodic shutdowns for cleaning or replacement of parts are obviously undesirable since it takes the equipment out of use until the cleaning and repairing is completed. This lost time constitutes a material expense to the owner of the equipment, particularly in view of the fact that this equipment is inherentlyv very expensive, is frequently ICC rented at a very high rental rate, and furthermore delays the completion of the work.

Furthermore, the cleaning, repairing and replacement procedures are expensive in and of themselves because of the additional labor and equipment required to effect same. Also, the compacted material which clings to the conventional equipment is normally so strongly adhered or welded thereto that it cannot be readily removed by tools or equipment available in the field or on the job, and therefore conventional compacting equipment in need of cleaning must frequently be conveyed over long distances to maintenance and repair shops which are capable of effecting the desired cleaning and repairing, thereby increasing the time which the tamping equipment is out of use.

In addition, the adhering material and the special cleaning devices for removing same cause an undesirable drag on the equipment and the expenditure of engine power to overcome the resistance of the material to the action of the cleaning devices, thereby frequently requiring the use of a more powerful engine than would otherwise be required.

Also, compacting machines presently available require facilities for carrying ballast in order to have sulficient weight to be effective.

Therefore, an object of this invention is to solve the foregoing problems by providing a novel compacting machine which is non-clogging and self-cleaning and which does not require the use of any rapidly depreciating cleaning devices, which does not require the use of ballast to obtain the proper effective weight, and which readily sheds the unwanted material, said unwanted material falling to the ground by the force of its oWn weight, and not requiring any engine power to accomplish the cleaning.

Another object is to provide a self-cleaning compacting machine utilizing one or more gangs of compacting wheels which are designed to provide a uniform ground contact pattern, which are capable of compacting a relatively wide expanse of ground during each pass thereover, and which are capable of oscillating during use so as to better conform to the ground contour being traversed and ride over obstructions without damage.

Still another object is to provide a novel self-cleaning compacting machine utilizing two or more gangs of compacting wheels disposed in juxtaposed parallel relationship and in which at least one of the gangs can be lifted from the ground while the other gang or gangs remain in contact therewith to increase the pressure applied by the gang or gangs remaining in contact with the ground and to facilitate turning of the machine.

Still another object is to provide a novel compacting wheel which is useful by itself or in a gang arrangement which is selfcleaning, and which achieves maximum compacting efiiciency and which, when used in a gang arrangement, prevents jamming of the machine by relatively large rocks or boulders which might be encountered.

These and other objects and advantages of this invention will more fully appear from the following description made in connection with the accompanying drawings wherein like reference characters refer to the same or similar parts throughout the several views, and in which:

FIG. 1 is a side perspective view of one preferred embodiment of this invention with both gangs of wheels in lowered operative position;

FIG. 2 is a top plan thereof;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a somewhat diagrammatic view of the machine of FIG. 1 with one of the gangs of compacting wheels in elevated tilted inoperative position;

FIG. 5 is a side elevational view of one of the compacting wheels of FIG. 1;

FIG. 6 is an end elevational view of the wheel of FIG.

FIG. 7 is an enlarged detail end elevational view of a portion of the wheel of FIGS. 5 and 6 showing the shape of the tampers and the manner of mounting same on the wheel disc; and

FIG. 8 is an enlarged perspective view of one of the tampers.

Reference is now made to the accompanying drawings for a more detailed description and better understanding of this invention.

FIGS. l and 3 inclusive show a two gang or two row compacting unit assembly A constituting one preferred embodiment of this invention, which assembly is mounted on drag structure D which in turn is connected to and mounted on a tractor T for pulling the compacting unit A over the ground to be compacted.

The compacting unit A includes a wheel supporting frame consisting of a horizontal elongate main frame member 10 which is transversely disposed with respect to the intended direction of travel of the apparatus, and which is disposed above the compacting wheels and which has a pair of depending connecting legs or draft members 11 attached to opposite ends thereof for attaching the compacting unit A to the drag structure D in a manner hereinafter described, whereby the pulling force of structure D is transmitted to the compacting unit through and by legs 11. A pair of rear axle supporting members or hearing standards 12 are secured to the main frame member 10 intermediate the ends thereof and extend rearwardly and downwardly therefrom for supporting the rear axle 13 on which axle are rotatably mounted three coaxial rear compacting wheels 14 which are identical in construction and design, and which are discussed in more detail hereinafter, said wheels 14 constituting the rear gang or row of compacting wheels.

The rear axle 13 is detachably mounted on the lower ends of its supporting members 12 by means of suitable U-clamps indicated in their entirety by the numeral 15.

The main frame member 10 also has a pair of front axle supporting members or bearing standards 16 secured thereto and extending forwardly and downwardly therefrom for individually supporting a pair of axially aligned front axles 17, each of said front axles having rotatably mounted thereon a pair of coaxial front compacting wheels 14' which are similar in all respects to the afore mentioned rear compacting wheels 14, the four coaxial front wheels 14 constituting the front gang or row of compacting wheels. Each of the three compacting wheels 14 in the rear gang are positioned half-way between, and in overlapping relationship with respect to, each adjacent pair of compacting wheels 14' in the front gang so as to work therebetween during use, the wheels of the two gangs traveling in contiguous parallel paths or tracks.

The drag structure D includes a forwardly disposed goose neck portion 18 which is connected to the tractor T. The goose neck 18 is hingedly interconnected with the tractor so that it and the entire drag structure are free to swing up and down relative to the tractor about a horizontal transverse axis. A horizontal transverse draft member 19 is rigidly secured to the goose neck, said transverse member having a pair of substantially parallel rearwardly extending drag arms 20 connected to the ends thereof, said compacting unit being mounted between and attached to said drag arms in the manner hereinafter described. The lower ends of draft members 11 of the compacting unit frame are pivotally connected to rear ends of their respective drag arms 20 by means of trunnions or pivots 21 to provide a first horizontal axis for forward and rearward swinging movement of the compacting frame about the horizontal axis transverse to the direction of travel provided by said'trunnions. This enables the compacting unit to freely rotate about the trunnion axis and to freely oscillate, swing or tilt back and forth relative to the drag strucure during use to enable the compactor to adjust to the ground contour being traversed and also to enable the wheelsto .ride over partially or completely submerged large boulders, rocks or other objects which might be encountered without undue strain on or damage to the compacting unit or the drag structure.

The pivotal connection between the legs 11 and the drag arms 20 also enables the rear gang of Wheels 14 to be lifted and swung upwardly out of contact with the ground from the lowered operative ground engaging and compacting position of FIGS. 1-3 to the raised inoperative non-compacting position of FIG. 4 by tilting the compacting frame forwardly. To accomplish this forward tilting of the compacting frame and elevation of the rear gang of compacting wheels, a power operated cable control unit or winch mechanism W is provided which is mounted on the rear of tractor T. A pulley 22 is supported above the goose neck by means of upstanding pulley support structure 23 secured to the top of the goose neck. A cable 24 is provided which has its forward end operatively connected to the winch, which cable is trained over the pulley 22 and extends rearwardly, the rear end of the cable being operatively connected to the main frame member 10 by a clevis-type connector 25. To limit the forward tilting movement of the compacting unit, a forwardly extending V-shaped stop member 26 is provided on each of the legs 11, which stop members are adapted to engage and rest upon their respective drag arms 20 when the compacting unit has been tilted forwardly a sufficient distance to elevate the rear gang of wheels from ground contact, which tilting movement is accomplished by actuation of the winch mechanism causing a forward pull on the cable 24 which pulls the frame member 1d and the rear gang of wheels upwardly and forwardly. In the illustrated arrangement, the wheel axes of the front and rear gangs are disposed on opposite sides of the pivot axis provided by trunnions 21.

When all of the seven compacting wheels of the illustrated compacting unit are in contact with the ground, the weight of the entire unit is substantially equally divided or distributed amongst each of the wheels. However, in some circumstances, it is desirable to increase the loading per wheel or per square inch of ground contact and in those circumstances, such is accomplished in the illustrated unit by operating the winch mechanism and pulling the cable forwardly so as to tilt the compacting frame forwardly and raise the rear gang of wheels from contact with the ground, thereby distributing the entire weight of the compacting unit amongst the four front wheels, thereby substantially increasing the loading thereon. Tilting the unit forwardly as previously mentioned also facilitates turning thereof, enabling shorter turns to be made.

The compacting wheels in each gang (those operating about a common axis) are preferably axially spaced far enough apart from each other so that there will be no build-up and bridging of material therebetween. Best results are attained when the wheels in any given gang are spaced at least twenty-four inches apart. By placing the wheels in adjacent gangs in staggered overlapping relationship, the wheel base of the compactor can be materially shortened, and more ground in any given width or span being traversed can be actually engaged and compacted during each pass thereover. Thus, more ground will be compacted by the illustrated staggered gang arrangement than would be the case if the rear gang were not used, since the rear Wheels track between the front wheels and compact the ground therebetween left uncompacted by the front wheels. Thus, the ground width spanned by the front wheels will be substantially completely compacted by the illustrated unit. Therefore, more efiicient use is made of the seven illustrated compacting wheels by arranging them in two adjacent gangs in staggered overlapping relationship than would be the case if they were all mounted in the same row or gang.

If they were all placed in the same row with the desired minimum self-cleaning spacing therebetween, then the overall width of the unit would be greater and would result in relatively large areas (represented by the space between the wheels) left uncompacted during each pass of the unit than in the two row staggered arrangement. Assuming that the front wheels of the illustrated staggered arrangement are the minimum self-cleaning distance apart, then if all seven wheels were placed in the same row while retaining the same overall Width illustrated and represented by the span of the front gang, thenthe unit would not be self-cleaning. The multiple gang arrangement also permits ready variation in the loading through the aforementioned tilting of the frame and lifting of the rear gang to an inoperative position.

The overlapping relationship of the wheels on adjacent gangs, and the location of the axle supports 12 and 16 between adjacent pairs of wheels in the same row also contributes to and also aids the self-cleaning, particularly when unusually adverse conditions are encountered. They also enable the wheels to be placed closer together with less likelihood of material building up therebetween.

With regards to the illustrated individual compacting Wheels, they are each identical in design and construction and therefore, a description of one is applicable to all. Each of the illustrated compacting wheels 14-14 includes a relatively large heavy solid flat-sided circular disk 27 which is imperforate except for a small central axial opening 27a formed therein for receiving the axle. A plurality of tamping feet or lugs 28 are rigidly mounted as by welding on the sides of the disk adjacent the outer periphery or rim 27b thereof, and arranged uniformly about the circumference thereof, with a circular circumferential equally spaced row of tampers being provided on each side of the disk, with the tampers on one side being in uniformly staggered relationship with respect to the tampers on the opposite side of the disk. The tampers are radially oriented with respect to the Wheel axis and extend beyond the rim of the disk a substantial distance and preferably far enough beyond said rim so that in normal usage the rim of the disk is not load bearing so that the entire load or weight of the compacting unit is carried by, and applied to the ground by, the tamping feet only. The illustrated tampers (best seen in FIGS. 7 and 8) are formed of metal bar stock which is rectangular in cross section and cut or otherwise shaped to the form illustrated, the sides of which are substantially fiat and smooth to enable them to readily shed any material which might tend to stick thereto and collect thereon. The tampers include an outer flat substantially horizontal ground engaging, load bearing, compacting face Zita and an inner face 28b and a mounting face 28c which is angularly offset from inner face 28b. The tampers are rigidly secured as by welding to the sides of the wheel disk with the mounting face 280 opposed to and in engagement with the side of the disk. The tampers are so mounted on the disk that the inner marginal edge 28d of the face 28b is co-extensive with and in alignment with the rim 27b of the wheel disk so that face 28b angles radially and laterally outwardly from the rim of the disk and in fact the entire tamping foot is oriented angularly laterally outwardly from the side and rim of the disk so that the entire tamper is disposed laterally or to one side of the disk and the load bearing compacting outer end or face 28a is laterally offset and spaced from the side and rim of the wheel disk by the space or distance x.

The compacting wheels are so designed that they will readily shed any material which sticks thereto, thus making the wheels self-cleaning and non-clogging and preventing the build-up of any material thereon which would become load bearing and thereby reduce the efficiency of the wheels. The design of the disk and the tampers, and the manner of mounting and arranging the tampers on the disk all contribute to the self-cleaning aspects of the wheel. The sides of the wheel disks which are preferably imperforate or substantially so (except for the axle opening) present a comparatively smooth flat surface which will readily shed any tenacious, clinging, or cohering material which might come in contact therewith. Thus, the wheel disk presents no pockets or supporting surfaces where material could collect and build up during use, and any material which moves past the tampers to the sides of the wheel disk must inevitably be shed thereby and fall onto the ground by the force of its own weight. The solid flat sides of the wheel disk also prevent the wheels from picking up rocks or boulders in such a manner as might jam the machine or cause damage thereto since there are no openings which could receive these rocks or boulders and enable the wheel to hold and physically lift same. The use of a solid fiat wheel disk also enables each wheel to be much heavier in weight than a spoke type Wheel and enables the wheels to be made heavy enough so that the proper effective compacting weight or loading is attained without requiring the use of additional ballast.

Because of the angular offset relationship of the tampers to the wheel disk and the rim thereof, the tamper ground contact area is positioned away from the rim, both radially and laterally. Therefore, any sticky material picked up by the tampers is disposed laterally outwardly of the disk and has nothing to stop it from going further as it moves radially inwardly and therefore never becomes load bearing and, therefore, after leaving the tamper, must necessarily fall to the ground since there is nothing to hold or support same. Because the entire tamper is disposed laterally outwardly of and away from the disk, the material picked up thereby does not overlie the rim of the disk, but is disposed to one side thereof, so that it will not, when moving radially inwardly, come in contact with or collect on the rim. Thus, the tampers are designed and mounted on the disk that the ground contact area thereof is away from the side of the disk so as to keep the material picked up thereby a safe selfcleaning distance from the rim of the disk while still attaining the loading desired. Also, the angular disposition of the tampers provides less tamper surface (only a portion of the length thereof) engageable by the material as it moves inwardly before it is released by the tamper than would be the case if the tampers extended straight out from the disk, in which case the full length of the tamper would be engaged by the inwardly moving material.

The angle Y at which the tampers are fastened to the disks is dependent in part on the length of the tampers beyond the rim of the disks. The major portion of the sticky material is picked up by the outer end portion of the tamper. Therefore, the outer end portion of a long tamper is laterally spaced from the side of the disk a greater distance than the outer end portion of a shorter tamper mounted at the same angle as the longer tamper, and the material picked up by the shorter tamper is therefore closer to the rim than the material picked up by the longer tamper. Therefore, the longer the tamper, the smaller the angle can be between the tamper and the side of the wheel disk. This angle is preferably relative ly small, but it should not be zero, that is, the inner face 281; of the tampers should be disposed angularly outwardly of the wheel disk and should not be in alignment therewith or be inclined inwardly so as to overlie the rim of the disk. The tampers should be offset at an angle at which the material that is picked up by the outer end of the tampers will be away from the side of the disk when it is pushed through between the tampers so that it can be readily shed by the wheels. If the tampers on opposite sides of the disk are too near parallel, they, in combination with the rim of the disk, will tend to retain material to the point where it will become load bearing. Also, it is desirable to have the angle of the tamper no greater than is necessary to successfully shed material. The reason for this is that the inner face 28b of the tamper provides a surface which to a certain degree is load bearing, particularly towards the outer end of the tamper, and the greater the angle of the tamper, the greater is the load bearing surface provided by inner face 28b. As the load bearing surface increases, the loading pressure per square inch decreases. Experience and testing indicate that best results are obtained when the tamper angle Y is within the range of 7 to 20 degrees, with an angle of about 13 degrees considered optimum. Also, the inner edge of the tamping face 28a is preferably laterally spaced from the side and rim of the wheel disk (distance X) by at least one-half inch and more preferably in the range of 2 to 3 inches in order to attain the self-cleaning attributes desired.

In order to prevent the rim of the wheel disk from becoming load bearing and thereby reducing the loading per square inch and compacting efficiency, experience and testing indicate that for best results the radius of the outer end or periphery of the tampers should be at least 110% of the radius of the disk. For purposes of economy and strength, the outer radius of the tampers is preferably not greater than 130% of the disk radius.

Also, it is desirable to keep the length or portion of the tampers which is disposed inwardly of the rim of the disk as short as possible consistent with adequate strength. The tampers are, as noted, radially arranged with respect to the center of the wheel disk. Thus, the inner ends of adjacent tampers are in radially inwardly converging relationship, and the longer the inner ends of these tampers are and the closer they are to the disk center, the closer together the inner ends of adjacent tampers get, and the closer they are together, the more likely they are to accumulate material therebetween which will wedge in the angles between the tampers and ultimately become load bearing. To achieve best results, the peripheral spacing of adjacent tampers on the same side (in the same row) is preferably limited within a certain range in order to achieve the loading per square inch desired, the ground contact pattern desired, and also to assure that the wheels will be self-cleaning. The peripheral spacing of the tampers depends in part upon the loading per square inch desired, the shape of the ground contact area, and the angle of the tampers relative to the disk. The smaller the angle Y between the disk and the tamper, the greater the peripheral spacing of the tampers should be to maximize the ability of the wheels to shed material and be self-cleaning. Testing and experience has indicated that best results are attained when the outer ends or peripheries of the tampers on the same side are about 15 to 20 inches apart (measured from their centerlines), or about 12 to 18 inches apart measured between the opposing marginal edges of the faces 28a on adjacent tampers, with the angle between adjacent tampers on the same side, preferably being about 2027 degrees. A preferred number of tampers is fourteen to eighteen per side, or a total of twenty-eight to thirty-six per wheel.

A typical wheel of this invention corresponding to those illustrated is formed as follows:

The wheel disk is formed of mild steel plate and is 72 inches in diameter and 2 inches thick, with a center opening which is 3 inches in diameter for receiving the axle. Each tamper is 3 inches by 2 /2 inches in cross section, providing a bearing surface of approximately 7 /2 inches, and extends radially outwardly 8 inches beyond the rim of the disk at an angle of about 13 degrees from the disk with the mounting face 280 being 4 /2 inches long, with the inner edge of the tamping face 28a being 2% inches (distance X) from the side of the disk. The

' wheel has twenty-eight tampers mounted thereon, fourteen on each side, with the peripheral spacing between the tampers on the same side being approximately 20 inches, the entire wheel assembly weighing approximately 3,000 pounds. When seven of these wheels are combined in a gang assembly similar to that illustrated in FIG. 1, the wheels in each gang are, in one preferred embodiment, spaced 36 inches apart, providing a unit having an overall width of approximately 13 feet and an overall length of approximately 12 feet, and a height of about 8 feet. The total weight of this unit is approximately 30,000 pounds, providing a loading pressure on the order of 600 pounds per square inch as applied by the tampers.

For best results, the Wheels are spaced, and the tampers arranged thereon in such fashion as to produce a substantially uniform ground contact pattern. Thus, the tampers are preferably equidistant from one another across the entire width or span of the machine. Thus, the distance between the outer edges of the tamper compacting faces 28a on immediately adjacent overlapping wheels is preferably the same distance as the space between the inner edges of the faces 28a of the two rows of tampers on each wheel, so that the actual compaction tracks of the tampers of the entire machine are parallel and equidistant from each other across the entire width of the machine.

From the foregoing, the advantages of this invention are readily apparent. The design and construction of the individual compacting wheels makes them self-cleaning, which self-cleaning is attributable primarily to the location of the ground contact area of the tampers laterally outwardly of and away from the wheel disks on which they are mounted, which self-cleaning is further enhanced by the staggered relationship of the tampers on opposite sides of each wheel and the substantially flat, smoothsurfaced, imperforate sides of the wheel disks themselves, and the manner of mounting the tampers on the wheel disks so that no pockets are provided Where material can collect and build up. The novel illustrated gang arrangement prevents bridging of material between adjacent wheels, provides for maximum efficiency of operation, and uniformity in ground contact pattern, the tiltable frame provides for variability of loading and easier and shorter turning, and the oscillatable nature of the compacting unit enables it to better conform to the ground contour being traversed and to ride over undesirable obstructions in its path of travel.

In additon to the aforementioned advantages of this invention, such as self-cleaning, variability of loading, etc., the compacting unit of this invention also has the advantage that it can be readily detachably mounted on any scraper (prime mover) presently available by simply substituting the compacting unit for the scraper, permitting the scraper power unit to be put back to the service for which is was originally intended whenever such is desired. Also, it will be understood that the compacting unit A can be mounted on or attached to any suitable prime mover or power plant desired, and that any suitable type of drag structure, including the one illustrated, can be used to connect the compacting unit with the power plant.

It will be further understood that the invention is not limited to the illustrated winch mechanism for tilting the compacting unit, and that any other suitable tilting means, including a hydraulic system, can be used Within the scope of this invention.

It will, of course, be understood that various changes may be made in the form, details, arrangement and proportions of the various parts without departing from the scope of this invention.

What is claimed is:

1. Ground compacting apparatus comprising draft means including a pair of elongate laterally spaced apart drag arms extending in the direction of travel of said apparatus and adapted for attachment to a vehicle for pulling same, and a compacting unit comprising an elongate frame member transversely disposed with respect to the intended direction of travel of said apparatus, each end portion of said member having an elongate draft member depending therefrom, the lower end portions of said draft members rotatably supported by said drag arms about a first horizontal axis transverse to said intended direction of travel, said frame member having axle supporting structure extending laterally downwardly therefrom from each side thereof intermediate said draft members, axle means supported by the lower end portions of said axle supporting structure, said axle means providing at least two parallel horizontal wheel axes transversely oriented and horizontally spaced with respect to said intended direction of travel, and compacting wheels mounted on said axle means for rotation about each of said wheel axes, the wheels operating on adjacent axes being in staggered overlapping relationship and uniformly axially spaced from each other, said wheels being physically spaced from each other whereby material picked up by the outer peripheries thereof and moving radially inwardly thereof is free to drop back onto the ground, said frame member and said draft members being tiltable about said first axis between a first position in which all of the compacting wheels are in lowered operative ground engaging compacting position and a second position in which the wheels operating about one of said axes are in a raised inoperative position and in which the weight of said last mentioned wheels is carried by the rest of the wheels still engaged with the ground, and power operated means for raising said last mentioned wheels and holding them in said inoperative position.

2. The apparatus of claim 1, wherein said compacting wheels comprise a wheel disk having a circular row of tamping elements mounted on each side thereof and uniformly spaced about the entire circumference thereof, the tamping elements on one side of the disk being in staggered relationship to those on the other side thereof, said tamping elements extending radially outwardly beyond the rim of said disk with the outer ground engaging compacting end portions thereof being laterally spaced from the side of said disk.

3. Ground compacting apparatus comprising draft means including a pair of elongate laterally spaced apart drag arms extending in the intended direction of travel of said apparatus and adapted for attachment to a vehicle for pulling same, and a compacting unit detachably mountable on said draft means between said drag arms, said unit including a wheel supporting frame which includes a transversely oriented elongate frame member extending between said drag arms and pivotally connected thereto by means of a pair of draft members which depend from opposite end portions of said transverse member and have the lower ends thereof pivotally connected to their respective drag arms for tilting movement of said transverse member and said draft members about a first horizontal transverse axis, said unit also including two opposed parallel rows of compacting wheels which are rotatably mounted on suitable axle means which are in turn mounted on and supported by axle supporting means extending between said axle means and said transverse member of said frame and disposed between adjacent pairs of compacting wheels in the same row, the wheels in each row being coaxial, the wheel axes of said rows being in parallel relationship and horizontally and transversely oriented and horizontally spaced with respect to said intended direction of travel and disposed on opposite sides of said first axis, the Wheels in one row being in uniformly staggered overlapping relationship with respect to those in the other row, all of said wheels being substantially equally physically spaced from one another whereby material picked up by any of said wheels is free to fall to the ground between said wheels, each of said wheels including a circular disk having mounted on each side thereof a circular row of uniformly spaced apart circumferentially arranged tamping elements which extend radially outwardly beyond the rim of said disk and whose outer ground engaging compacting end portions are laterally spaced from the side and rim of said disk, the tamping elements on one side of the disk being in uniformly staggered relationship with respect to those on the opposite side thereof, said transverse member and said draft members being tiltable relative to said drag arms between a first position in which both rows of wheels are in lowered operative ground engaging compacting position and a second position in which the rearwardmost row of wheels is in a raised inoperative position in which said rearwardrnost row of wheels is out of engagement with the ground and the entire weight thereof is carried by the forwardmost row of wheels, stop means engageable with said depending draft members and said drag arms for limiting the tilting movement of the frame between said first and second positions, and power operated means for effecting said tilting movement.

4. A ground compacting wheel comprising a circular disk, said disk having mounted thereon on each side thereof a circular series of tamping elements uniformly spaced about the entire circumference of said disk, the tamping elements on one side of said disk being in staggered relationship to those on the other side of said disk,

said tamping elements being disposed entirely laterally of the rim of said disk, said tamping elements extending radially outwardly beyond said rim and extending angularly outwardly from the side of said disk, the outer ground engaging compacting face of said tamping elements being laterally spaced from the rim of said disk.

5. The wheel of claim 4, wherein said tamping elements extend angularly outwardly at an angle of about 7 to 20 degrees from the vertical.

6. The compacting wheel of claim 4, wherein said tamping elements are elongate members which are radially oriented with respect to the Wheel axis and the distance between the opposing marginal edges of the outer ends of adjacent tamping elements on the same side is about 12 to 18 inches.

7. The compacting wheel of claim 4, wherein said disk has substantially flat parallel sides and is a substantially completely imperforate body except for a central axle receiving opening formed therein.

8. The compacting wheel of claim 4, wherein said tamping elements extend beyond the rim of said disk a distance equal to at least of the disk radius.

9. The compacting wheel of claim 4, wherein the inner ends of said tamping elements terminate immediately adjacent the rim of said disk.

10. The compacting wheel of claim 4, wherein the outer compacting face of said tamping elements is laterally spaced from the rim of its disk at least /2 inch.

11. Ground compacting apparatus comprising an elongate frame member transversely disposed with respect to the intended direction of travel of said apparatus, said member having a pair of longitudinally spaced apart elongate draft members depending therefrom, the lower end portions of said draft members having pivots therein and drag arms pivotally secured thereto thereby providing a first horizontal axis transverse to said intended direction of travel during use, said frame member having axle supporting structure depending therefrom from each side thereof intermediate said draft members, axle means supported by the lower end portion of said axle supporting structure, said axle means providing at least two parallel horizontal wheel axes transversely oriented and horizontally spaced with respect to said intended direction of travel on opposite sides of said frame member, compacting wheels mounted on said axle means for rotation about each of said wheel axis wherein the wheels operating about one of said axes are movable between a lower operative ground engaging position and a raised inoperative position by the rotation of said draft members about said first axis, the wheels operating about the other of said axes being adapted to be in compacting engagernent with the ground when the first mentioned wheels are in each of said positions.

12. The apparatus of claim 11 including power operated means for raising said rear wheels to and holding them in said raised inoperative position, rotating said wheels about said first axis.

13. The apparatus of claim 11 wherein said wheels are physically spaced apart from each other whereby any material picked up by the wheel peripheries and movable axially inwardly therefrom is free to fall back onto the ground being transversed by said apparatus.

14. The apparatus of claim 11 wherein said compacting wheels include circular wheel disks, said disks having a circular row of tamping elements mounted on each side thereof which are uniformly spaced about the circumference thereof, the tamping elements in one row being in staggered relationship with respect to those in the other row, said tamping elements extending radially outwardly beyond the rim of said disks, the outer ground engaging compacting surfaces of said tamping elements being laterally spaced from the sides and rims of said disks.

15. The apparatus of claim 11 wherein said compacting wheels comprises a row of co-axially mounted compacting wheels supported by said frame, each of said compacting wheels including a circular substantially flat-side wheel disk having a circular row of tamping elements mounted on each side thereof and disposed laterally thereof which are uniformly spaced from each other about the entire circumference of said disk, the tamping elements on one side of the disk being in staggered relationship with repect to those on the other side of the disk, said tamping elements extending radially outwardly beyond the rim of 12 said disk, said wheels being axially spaced from each other a distance of at least twenty-four inches.

16. The apparatus of claim 15, including axle means on which said wheels are rotatably mounted and axle supporting means constituting a part of said frame and disposed between adjacent pairs of compacting wheels.

17. The apparatus of claim 15 wherein said tampers are equally spaced from each other axially of said row throughout the entire length thereof.

References Cited by the Examiner UNITED STATES PATENTS 466,771 1/1892 Clark 172-548 544,837 8/1895 Archer et a1. 172548 1,064,265 6/1913 Waterman 94-50 1,847,280 3/1932 Tomlinson 172-556 2,024,184 12/ 193 5 Ritchie 94-50 2,703,515 3/1955 Richards 94-50 2,755,713 7/1956 Harrison 94-50 2,959,231 11/1960 Heilrnan 17242 2,978,967 4/1961 MacDonald 94-50 2,991,836 7/1961 Swanson 9450 3,080,799 3/ 1963 Calfee 9450 3,128,831 4/1964 Arndt 17248 JACOB L. NACKENOFF, Primary Examiner.