US 3754711 A
A hopper body is mounted on the bed of a truck for spreading particulate matter over a wide area as the truck moves forward. Normally some special means is mounted near the rear of the truck for broadcasting the particulate matter. For example, in the northern part of the United States a dump truck may spread a mixture of salt and sand on roadways following a snow storm to melt the snow and provide better traction for following vehicles. Dual conveying belts are located in the bottom of the hopper to move the salt, sand or other particulate material to the broadcasting means at the rear of the hopper. Each belt runs over both a driving drum located beyond the rear wall of the hopper and an idler drum located adjacent the front wall of the hopper. Guide means are located adjacent each drum to force the belt into parallel upper and lower paths with the spacing between said paths being less than the diameter of either drum. The sides of the hopper are inclined downwardly toward the conveyors to prevent material from collecting in corners and to assist gravity feed of material to said conveyors.
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Description (OCR text may contain errors)
United States Patent Gledhill LOW PROFILE FEEDING SPREADER  Inventor: William Gledhill, Galion, Ohio  Assignee: The Gledhill Road Machinery Company, Galion, Ohio [22 Filed: Feb. 22, 1972 21 Appl. No.: 227,944
Primary Examiner M. Henson Wood, Jr. Assistant Examiner-John .1. Love Attorney-Robert J. Fay
[ Aug. 28, 1973  ABSTRACT A hopper body is mounted on the bed of a truck for spreading particulate matter over a wide area as the truck moves forward. Normally some special means is mounted near the rear of the truck for broadcasting the particulate matter. For example, in the northern part of the United States a dump truck may spread a mixture of salt and sand on roadways following a snow storm to melt the snow and provide better traction for following vehicles. Dual conveying belts are located in the bottom of the hopper to move the salt, sand or other particulate material to the broadcasting means at the rear of the hopper. Each belt runs over both a driving drum located beyond the rear wall of the hopper and an idler drum located adjacent the front wall of the hopper. Guide means are located adjacent each drum to force the belt into parallel upper and lower paths with the spacing between said paths being less than the diameter of either drum. The sides of the hopper are inclined downwardly toward the conveyors to prevent material from collecting in corners and to assist gravity feed of material to said conveyors.
6 Claims, 7 Drawing Figures Patented Aug. 28, 1973 3,154,111
3 Sheets-Sheet 1 f! I El 8,
PR/OR ART Patented Aug. 28, 1973 5 Sheets-Sheet 2 LOW PROFILE FEEDING SPREADER BACKGROUND OF THE INVENTION This invention is primarily concerned with hopper bodies which are mounted on the beds of trucks during the winter for spreading salt and sand on highways particularly including dump trucks. However, it would be appreciated that the described structure is not limited to this specialized use and could logically be used for spreading fertilizer, aggregate or other particulate matter.
Because the hopper must be mounted on existing structures such as the bottom of a dump truck bed, its design is limited in width and length. Conventional hopper structure includes a body having a substantially rectangular shape in plan and with inclined sidewalls converging toward the bottom centerline thereof. In the bottom of the hopper, juxtaposed to the converging sidewalls, is a conveyor belt which is mounted below the lowest interior portion of said body. The conveyor belt is normally mounted on two or more drums, one being a drive drum which moves the belt in an endless path to conduct the particulate material from the front to the back of the truck and the others being idler support drums.
At the rear of the truck mounted near the centerline thereof is a means for broadcasting or spreading the particulate material over a wide path as the truck moves forward. This broadcasting means may take many forms and any conventional strucutre may be used. Because they are well known in the art, no detailed description of this structure appears necessary.
There are two prime problems with the existingprior art structures, (1) the relatively high center of gravity of the filled hopper body presenting a hazard and (2) the high loading height which is an inconvenience and requires more time and more expensive equipment to accomplish. Both of theseproblems are principally due to the great amount of lost space within the dump truck bed due to the inclined sidewalls of the hopper.
The high center of gravity becomes a safety hazard when trucks are moving along roads during the winter season where the roads are covered with ice and snow. This traditional driving hazard may result not only in a slippery surface but also an unusually high crown on the road due to the collection of ice or snow in that area. The combination of these inherent hazards with the high center of gravity of the hopper tends to make the vehicle much less stable than if the center of gravity were lower. These built-in hazards are multiplied in the winterbecause ice and snow may cause unexpected slipping and sliding into curbs or snow banks with resultant tipping of the vehicle.
Obviously, the desire exists for lowering the center of gravity. Certainly, this could be accomplished by reducing the angle of inclination of the sides but this is not satisfactory because this would present an additional problem because of the angle of repose of salt and/or the combination of salt and sand. When winter comes, the times that salt and sand are being spread on the road are usually times when snow or sleet is falling. Often the trip made by the truck from the loading site to the beginning of the spreading operation will result in considerable precipitation falling on the salt which could result in a minimal cementing of the salt particles. It is conventional to have the sides of the hopper inclined at approximately a 45 angle to overcome this tendency of agglomeration. Thus, it is difficult to lower the center of gravity because of the inherent requirement of 45.
The cause of the center of gravity problem, of course, is the lost space which results from the 45 angle. Certainly, one logical way to accomplish the desired results is to increase the width of the conveyor belt. Any amount that the width of the moving conveyor belt is increased will bring about a corresponding and beneficial reduction in the cross-section area of the lost spaces. But it is evident that any increase in the width of the moving conveyor belt also brings about a corresponding increase in the torque required to move the belt and while some increase in width can be made and is recommended, there is a practical limit to the widening beyond which the torque problem becomes serious. Thus, attempting to solve the problem by conveyor belt widening, only, may not be an acceptable solution to the problems.
BRIEF DESCRIPTION OF THE INVENTION The solutions to these problems are provided by the instant inventionin novel fashion by providing two spaced-apart conveyor belts in the bottom of the hopper body which may, if desired, be powered by two separate, although synchronized, motors or a common drive shaft. The sidewalls are still partially inclined at a 45 angle butthey are much shorter. A triangular shaped piece is mounted in the bottom of the body between the belts, its sides being inclined at the aforementioned 45 angle to each side of its peak.
Calculations of void space revealed a discovery not readily obvious; namely, that the use of two conveyor belts spaced apart rather than one with the same total width brought about a reduction in lost space in the ratio of 2 to l thus, materially lowering both the center of gravity and the loading height. Another way of illustrating the value of two conveyors instead of one is to calculate the width needed for a single belt to have an equivalent lost space. Calculations indicate that the width of a single conveyor must be twice the combined widths of the two conveyors to have the same lost space. It is also obvious that if the single conveyor would be used of double the total width, it would increase the required torque in the same proportion and to an intolerable amount.
Analysis revealed that to provide the minimum lost cross-sectional area in the hopper, the peak of the triangular element should be exactly the same height as the heights of the two inclined portions of the sides of the hopper.
To further lower the profile or center of gravity of the hopper body it was conceived that the bottom of the hopper itself could be lowered by lowering the load carrying surface of the conveyor belts. There is a limitation, however, which is the upper surface of the dump truck bed. There is also the limitation of the upper sur-' face of the drive drum. The upper surface of the conveyor belt should be approximately level from front to back, insofar as the load carrying surface is concerned. Thus, the minimum height of the load carrying portion of the belt must be the uppermost elevation of the drive drum which normally is located at the rear of the hopper body. The instant invention has removed the drive drum from inside the hopper body and located it beyond the rear wall of the same. This allows the axis of the drive drum to be lowered because the bottom of the drive drum will not then encounter the bottom of the hopper or the bottom of the dump truck bed. Thus, with the drive drum lowered, the conveyor belt surface and the hopper bottom can also be lowered.
Deflecting means are provided adjacent the drive drum to deflect the lower portion of the belt upward so that it passes just above and approximately parallel with the bottom of the dump truck bed. The deflecting guiding means could be a slide bar, a rotating idler drum or some equivalent structure. Similar deflecting and guiding means are provided adjacent the upstream idler drum at the front of the hopper to deflect the upper surface of the conveyor belt downward. In this manner, the spacing between the upper and lower paths of the conveyor belt is less than the diameters of either the driving drum or the idler drum.
Another innovation which is an improvement is the location of the broadcasting means at the rear of the truck. It is set to one side or the other of the truck, preferably the left-hand side. This allows the broadcasting means to fling salt in a wide arc which can cover two or more lanes of highway. In this manner, the truck can drive down the right-hand side of the road and spread salt evenly across both lanes. This obviously minimizes the number of passes a salt truck must make to cover the road,'as well as shortening the time required to make the road safe to travel.
To allow the placing of the broadcasting means to the left side of the truck, an auger is provided to conduct the salt or particulate material from the discharge end of the conveyor belts to the broadcasting means. An auger is preferred in this instance because it is more controllable. An auger is not an acceptable alternative to the conveyor belts mounted within the hopper because augers become clogged and choke quite easily under heavy vertical load. Experiments indicated that a similar result might occur with the auger mounted outside the hopPer body and to minimize this possibility, the auger is synchronized with the motor or motors driving the conveyor belts whereby the conveyor belts move the salt more slowly than does the auger.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevational view illustrating the general environment of the invention.
FIG. 2 is a sectional view taken through the hopper illustrated in FIG. 1 and showing the inventive concepts.
FIG. 3 is a sectional view through a truck similar to that illustrated in FIG. 1 and showing the shape of the prior art structures.
FIG. 4 is a sectional view taken along line 4-4 of FIG. 3.
FIG. 5 is a sectional view taken along line 5-5 of FIG. 2.
FIG. 6 is an elevational view taken along line 6--6 of FIG. 1 showing a centerline mounted broadcasting means.
FIG. 7 is a modification of FIG. 6 showing the broadcasting means located to the left-hand side of the truck.
PREFERRED EMBODIMENTS Considering particularly FIG. I, a dump truck 10 is illustrated having a container or hopper body 14 mounted within its dump bed 12. A broadcasting means 16 is mounted on the rear of the container 14. Basically, this combination is conventional.
FIGS. 3 and 4 illustrate the prior art. The container 18 is substantially rectangular in plan view and includes vertically extending sidewalls 20 which merge with inwardly converging portions 22 in the lower section of the hopper. Bracing elements 24 are welded to the sloping sidewalls 22 to give added strength against buckling from the heavy load inside the container 18.
It will be observed that sloping sidewalls 22 are inclined at approximately 45 from the horizontal for the purpose of minimizing the possibility of salt and/or sand sticking to the walls. The angle is greater than the angle of repose of such materials, particularly under the vibrations which will be inherent in the movement of the truck. However, a certain safety factor is necessarily built-in.
At the bottom of the container 18 is a conveyor belt 26 which runs over a drive drum 28 near the rear and an idler drum 30 near the front. It will be observed in FIG. 4 that the spacing between the upper and lower paths of the conveyor belt 26 is approximately the same as the diameters of the two drums 28 and 30.
Particulate matter will be in the hopper body 18 and will flow by gravity, guided by the sloping sidewalls, to the upper surface of the belt 26. Rotation in a clockwise direction as viewed in FIG. 4 will move particulate matter to the rear of the truck where it will be passed to a spreading device and dumped on raod beds. The problems which exist in the art include the obviously high center of gravity inherent in a loaded hopper body 18 and the inconveniently high loading height due to the lost space inherent in the sidewalls 22 inclined at a 45 angle.
FIGS. 1, 2 and 5 through 7 illustrate modified structure which eliminates part ofthese two problems. The first modification of the conventional structure was to provide two identical parallel conveyor belts 32 and 34 to replace the single conveyor belt 26 of the prior art. Because the two conveyor belts 32 and 34 are identical, only one will be discussed in detail.
As can be seen in FIG. 2, the provision of two conveyor belts, each of which is the same width as the conveyor belt 26 considerably reduces the transverse span which must be bridged by the inclined sides. After the concept of dual conveyor belts was formulated, it became obvious that the shorter the height of the inclined sidewalls 36, 38, the less would be lost space which is otherwise usable for the particulate material.
Another fact became important in the design of the structure and that was that there was a calculable reduction in lost space by the use of two belts spaced apart rather than being in juxtaposed position or a single belt of the same total width. The creation of this space between the belts serves to reduce the dimensions and the area of the inclined sides which create the lost space.
After the concept of spacing the conveyor belts apart became a part of the design, it was concluded that the gap between the belts should be bridged by a triangular shaped element 40 having its corner or peak 42 approximately bisecting the gap between the two belts. For reasons before enumerated, with respect to sidewalls 36 and 38, the sides of the triangle 40 are inclined at approximately 45 from the horizontal.
With these given parameters, calculations were made to design a hopper body with a minimum of lost space due to the angled sides 36, 38 and the triangular element 40. Mathematical calculations produced the result that the minimum lost space occurs when the elevation of peak 42 is identical with the height of the angled walls 36, 38. In other words, the elevation above the ground of the peak 42 should be the same elevation as the merger points between the sloped sidewalls 36, 38 and the upwardly extending vertical walls 44.
As an illustration, the maximum allowable width in the design of a hopper body is limited by the sidewalls of the dump bed 12. Conventionally, the designer has approximately 78 inches to work with. Calculations indicate that the proper horizontal dimensions from one side of the hopper to the other are 7% inches, 24 inches, 15 inches, 24 inches, and 7% inches respectively for the horizontal distance of the left sloped sidewall 36, the conveyor belt 32, the spacing across the bottom of triangle 40, the conveyor belt 34 and the horizontal distance of the right sloped sidewall 38. It will be recognized that the standard 24 inch widths of the conveyor belts 32 and 34 have an effect on the other dimensions. However, narrowing or widening the conveyor belts simply changes the other dimensions, it will not change the proportional ratio between the height of peak 42 and the height of the sides 36 and 38. On this 78 inch wide hopper body, the lost space is approximately 112.5 square inches.
Calculations indicate that if the height of the inclined sides were not equal to the height of the central triangular shaped elementless efficiency in lost space reduction results. It can be shown that in the example of the total of 78 inches with which to work dimensions were chosen such as inches, 24 inches, 10 inches, 24 inches and, 10 inches respectively, for the previously enumerated elements which would cause the height of the sloping sides to be each 10 inches and of the triangular shaped central element to be 5 inches, that the lost space would calculate to be 125 square inches. Compared to the previous example giving 1 12.5 square inches, this is obviously lessefficient for the reduction of the problems.
Calculations still retaining the 78 inch working width example which would have horizontal dimensions of inches, 48 inches, and 15 inches, would indicate that the two conveyor belts are juxtaposed or that one belt is used of double the width. The inclined sides would be the only remaining lost space but their area would calculate to 225 square inches which can be seen to be exactly double the 1 12.5 square inches in the first and ideal example. This clearly illustrates the value of spacing the two conveyor belts apart by an ideal dimension.
As will be obvious to those having ordinary skill in the art, the sloped sidewalls 36 and 38 cannot exactly merge with the edge of the conveyor belts and regardless of other factors, the inclined sidewalls and the walls of the triangle 40 must overlap the conveyor belt; otherwise, particulate materials will fall off the edge of the belt and tend to collect in the underlying structure. Overlaps of the inclined walls with the belt are conventional.
It will also be obvious to those in the field that wear occurs on the sidewall at the lower terminus of said wall where it overlaps the conveyor belt. The reasons for this are not material, the fact is it exists and the reasons are well known to all mechanical engineers.
Eventually wear on the edges will require repair and for this reason shields or wear plates 46, 48, and 52 are shown bolted to the inclined walls and overlying the horizontal surface of the conveyor belts. The upper bolt heads holding the shields to the inclined walls may be recessed into the shielding members themselves if desired, to minimize wear on the bolt heads but this is unnecessary in fact. In practice it has been found convenient to change the shields 46 through 52 when they are worn to an unusable extent and at that time it has been found best to replace the bolts because of the inherent abrasion and corrosion of the salt.
Noting particularly the belt 32 in FIG. 5 it will be observed that the drive drum 54 is mounted beyond the rear of the container 14 and that its axis is lower than the axis of the idler drum 56. This location is permitted by the inclusion of a deflecting guide means 58 adjacent the drum 54. As will be observed the guide means 58 in the illustrated embodiment is a slide plate which deflects the lower portion of the belt 32 upwardly from the lowest point on the drive drum 54 to a spot approximately the same elevation as the lowest point on the idler drum 56. A similar guide plate 60 is locatedadjacent the idler drum 56 and serves to deflect the belt 32 downward to approximately the elevation of the upper surface of the driving drum 54.
While curved guide plates 60 and 62 are illustrated and are preferred, cylindrical rollers could also function adequately to deflect the belt and such is within the inventive concept. It will be understood that the drive drum may or may not have a sprocket and chain type of drive as is conventional. The mechanism for turning the belt 32 is relatively immaterial as long as structureis included which will cause the belt to move in the path generally illustrated in FIG. 5.
Two additional features will be observed in FIG. 5 and one is the result of the other. Blocks or crosspieces 62 extend transversely across the belt 32 to push the particulate material toward the rear of the container as the belt rotates. The twoguides 58 and 60 have an inclined or open mouth 64 at their inlet end to allow the crosspieces 62 to slip into the mouth and be deflected accordingly.
Turning particularly to FIG. 6, it will be observed that the spreader, or broadcasting device 16 is located in approximately the center of the back of the container l4. Appropriate funneling mechanisms or augers are designed to deflect or push the material from the conveyor belts to the spreading device. This is the conventional placement of the broadcasting device 16 and it will work in this position. However, the preferred manner of mounting the broadcasting device 16 is illustrated in FIG. 7 wherein it is placed on the left-hand side of the container where it will allow the broadcast material to deflect both to the left of and behind the container. With this relocation it is obvious that the truck can-move down the highway while broadcasting the material over both the right and the left lane sides of the highway. In this manner, two lanes of traffic can be covered in one traverse of the area. This greatly minimizes the number of miles required to spread the salt and the time required to make the road safe for traffic.
Additional structure is provided when the left-hand mounting of the broadcasting device 16 is included in the specifications. It includes an auger 66 which meters the particulate material to the broadcasting device. As previously indicated, screws or augers are not desirable in the container 14 itself, however, they will work satisfactorily when they are not subject to high vertical load and possible clogging and choking. In this instance, the
drive motors for the driving drums 54 are synchronized with the auger 66 and will prevent clogging. To insure this, the auger 66 is designed to move material to the spreader 16 faster than the conveyor belts move it out of the container.
With this modified structure as previously discussed, it will be obvious that the center of gravity of the loaded container 14 of FIG. 2 will be substantially lower than previous designs. For example, the illustrated embodiment in FIG. 2 is approximately 14 inches lower from the center of gravity of the container of FIG. 3 and both are of approximately the same width and cross-sectional area.
It is obvious that other mechanisms than those illustrated may be used to distribute particulate material after it has been conveyed to the rear of the container 14. Many such conventional structures are known to those of ordinary skill in the art and no detailed discussion appears necessary.
1. In the combination of a container for mounting on the bed of a truck and means for broadcasting particulate material over a wide path,
the top of said container being substantially rectangular,
said broadcasting means being mounted near the rear of the container,
conveying means for conducting particulate material from the container toward the broadcasting means, said conveying means being mounted with its load carrying surface below the lowest portion of the container,
the lower portion of the sides of the container being inclined inwardly toward the conveyor and the upper portion extending substantially vertically, the improvement comprising,
the conveying means including at least two conveyor belts mounted in parallel, each belt having an upper and lower surface and being mounted on one driving drum and one idler drum, then rotational axis of each idler drum being at an elevation above the rotational axis of the drive drums, each said driving drum being mounted beyond the rear wall of the container and the lowermost portion of the driving drum extending below the truck bed, each idler drum being mounted near the front wall of the container and each pair of drums working together to move the belt in parallel, substantially horizontal upper and lower paths between the front and rear,
guide means adjacent each driving drum for deflecting the lower surface of the belts upward tne sec ond guide means adjacent each idler drum for deflecting the upper surface of the belts downward whereby the spacing between the upper and lower paths of each belt is less than the diameter of its associated driving drum and idler drum.
2. The combination of claim 1 including a horizontal space between the two belts, the space being filled by a triangular shaped element, the uppermost corner of the element being a right angle and said corner bisecting the space between the belts,
the highest elevation of said corner being substantially equal to the highest elevation of each of the inclined portions of the sides of the container.
3. The combination of claim 2 wherein the broadcasting means is mounted near one rear corner of said container.
4. The container of claim 3 including auger conveying means to move particulate material from the rear of the conveyor belts to the broadcasting means.
5. The container of claim 1 including auger conveying means to move particulate material from the rear of the conveyor belts to the broadcasting means.
6. The combination of claim 1 including wear plates attached to the inclined sidewalls and triangular shaped element adjacent the belts to minimize wear on the sidewalls and element.