An assembly includes first and second shafts and first and second sprockets. The first shaft has a first and second ends and a first longitudinal axis of rotation. The first sprocket is attached to the first shaft proximate the first end of the first shaft. The first sprocket rotates with the first shaft. The second shaft is spaced from the first shaft by a distance, the second shaft having a first end spaced from the first end of the first shaft by the distance, a second end spaced from the second end of the first shaft by the distance, and a second longitudinal axis of rotation substantially parallel to the first longitudinal axis of rotation. The second sprocket is attached to the second shaft proximate the second end of the second shaft. The second sprocket rotates with the second shaft. The distance is adjustable.

BACKGROUND OF INVENTION

Field of Invention

In agricultural use, a conventional pneumatic spreader for particulate material such as granular fertilizer includes a tank configured to be pulled across a ground surface in a travel direction.

Description of Related Art

Such a spreader typically has a pair of booms that extend transversely outwardly from the tank, in a lateral direction relative to the travel direction. U.S. Pat. No. 5,052,627, which is hereby incorporated by reference, describes such a conventional spreader. As shown in FIGS. 1 and 3 of the '627 patent, particulate material in tank 10 is conveyed by a pair of belts 28 into guides 60, which feed material through the pipes 13 of booms 12. As shown in FIG. 1, spreader nozzles 18 and 19 allow application of the particulate material to a ground surface over which the spreader travels. A conveyer belt 29 on a right side (as viewed in FIG. 1) of tank 10 feeds into guide 60 to boom 12 on the right side of frame 11. Similarly, a conveyor belt 29 on the left side of tank 10 feeds through guide 60 to a boom on the left side of the frame 11 (not shown).

U.S. Pat. No. 5,950,933, which is hereby incorporated by reference, describes a pneumatic material spreader for distributing two types of particulate materials simultaneously. As shown in FIG. 1 of the '933 patent, tank 10 is divided into two sections by divider wall 19. (column 4, line 47). Belt 46 delivers material from compartment 24 while belt 60 delivers material from compartment 25. As shown in FIGS. 2 and 3 of the '933 patent, a first set of the belts 46 and 60 delivers the first and second materials from compartments 24 and 25, respectively, to right boom 71. Similarly, a second set of the belts 46, 60 delivers materials from compartments 24 and 25 respectively, to a left boom 70.

OVERVIEW OF THE INVENTION

An assembly comprises a first shaft, a first sprocket, and second shaft, and a second sprocket. The first shaft has a first end, a second end, and a first longitudinal axis of rotation. The first sprocket is attached to the first shaft proximate the first end of the first shaft, wherein the first sprocket rotates with the first shaft about the first longitudinal axis of rotation. The second shaft is spaced from the first shaft by a distance, the second shaft having a first end spaced from the first end of the first shaft by the distance, a second end spaced from the second end of the first shaft by the distance, and a second longitudinal axis of rotation that is substantially parallel to the first longitudinal axis of rotation. The second sprocket is attached to the second shaft proximate the second end of the second shaft, wherein the second sprocket rotates with the second shaft about the second longitudinal axis of rotation. The distance is adjustable.

This summary is provided to introduce concepts in simplified form that are further described below in the Detailed Description. This summary is not intended to identify key features or essential features of the disclosed or claimed subject matter and is not intended to describe each disclosed embodiment or every implementation of the disclosed or claimed subject matter. Specifically, features disclosed herein with respect to one embodiment may be equally applicable to another. Further, this summary is not intended to be used as an aid in determining the scope of the claimed subject matter. Many other novel advantages, features, and relationships will become apparent as this description proceeds. The figures and the description that follow more particularly exemplify illustrative embodiments.

While the above-identified figures set forth one or more embodiments of the disclosed subject matter, other embodiments are also contemplated, as noted in the disclosure. In all cases, this disclosure presents the disclosed subject matter by way of representation and not limitation. It should be understood that numerous other modifications and embodiments can be devised by those skilled in the art which fall within the scope and spirit of the principles of this disclosure.

The figures may not be drawn to scale. In particular, some features may be enlarged relative to other features for clarity. Moreover, where terms such as above, below, over, under, top, bottom, side, right, left, etc., are used, it is to be understood that they are used only for ease of understanding the description. It is contemplated that structures may be oriented otherwise.

DETAILED DESCRIPTION

An exemplary embodiment of agricultural spreader20allows for differential particulate application rates of material from tank30through different portions of boom22. As shown inFIG. 1, boom22extends outwardly from tank30and is configured to distribute the particulate material. As shown inFIGS. 1 and 3, tank30includes two compartments32and34for holding supplies of different particulate materials in a typical application. In another use, the compartments32and34could hold the same type of particulate material. Lower conveyor assembly36delivers material from compartment32to boom22, while upper conveyor assembly38delivers particulate material from compartment34to boom22. While the drawing figures show the conveyor assemblies36,38only on a left side of apparatus20, it is to be understood that similar, mirror-image conveyor assemblies are also provided on a right side of spreader20. As shown inFIG. 2, in an exemplary embodiment, lower conveyor assembly36is divided into respective outward and inward portions36a,36band36d,36c. Such outward and inward portions are separated by wall40; one wall40is positioned between outward portion36aand inward portion36b; another wall40is positioned between outward portion36dand inward portion36c. Similarly, upper conveyor assembly38is divided into respective outward and inward portions38a,38band38d,38c. Such outward and inward portions are separated by wall40; one wall40is positioned between outward portion38aand inward portion38b; another wall40is positioned between outward portion38dand inward portion38c.

Boom22includes boom portions24a-24dalong a longitudinal extent thereof. Left boom arm22aincludes boom portions24aand24b; right boom arm22bincludes boom portions24cand24d. Referring toFIGS. 1-3(as partially illustrated), for distribution of particulate material from compartment32of tank30, lower conveyor belt56aon lower conveyor side36ais associated with boom portion24a; lower conveyor belt56bon lower conveyor side36bis associated with boom portion24b; lower conveyor belt56con lower conveyor side36cis associated with boom portion24c; and lower conveyor belt56don lower conveyor side36dis associated with boom portion24d. For distribution of particulate material from compartment34of tank30, upper conveyor belt58aon upper conveyor side38ais associated with boom portion24a; upper conveyor belt58bon upper conveyor side38bis associated with boom portion24b; upper conveyor belt58con upper conveyor side38cis associated with boom portion24c; and upper conveyor belt58don upper conveyor side38dis associated with boom portion24d.

In an exemplary embodiment, the particulate application rates can be different for each of the materials from compartments32and34between different sections24athrough24d, for example, along the longitudinal extent of boom22. A separate motor66a-66dand68a-68dis associated with each of the lower and upper conveyor belts56a-56dand58a-58d, each motor66a-66dand68a-68dbeing configured to independently control a distribution rate of the particulate material on its respective conveyor belts56a-56dand58a-58dand through its respective boom portion24a-24d.

For example, as shown inFIG. 1, if spreader20travels across a ground surface so that it turns in leftward turn direction28, the leftmost boom portion24awill travel at the slowest speed relative to the other boom portions, and the rightmost boom portion24dwill travel at the highest rate of speed while traversing the turn28. Accordingly, in order to uniformly spread particulate material on a ground surface below the entire boom structure22, particulate material should be deposited to the ground surface at a faster application rate in boom portion24das compared to that in boom portion24a. Moreover, particulate application rates through boom portions24band24cshould be prorated between the speed extremes at boom portions24aand24dto ensure a uniform application of particulate material to the ground surface across the entire width of spreader20.

Material moved on a conveyor side36afalls by gravity into lower guide42a. Similarly, material moved by lower conveyor side36bfalls by gravity into lower guide42b. Each of lower guides42a,42bincludes a plurality of compartments44, each of the compartments44fluidly connected to one of outlets46. Each of the outlets46is in turn connected to a boom pipe48, which has a spreader nozzle50at its terminus.

Referring toFIGS. 2 and 3, material moved by upper conveyor side38ais fed by gravity to upper guide52a(not shown, as it is positioned to the left of the cross-sectional plane C); material fed by upper conveyor side38bfalls by gravity into upper guide52b. Material conveyed by upper conveyor side38cfalls by gravity into upper guide52c, and material conveyed by upper conveyor side38dfalls by gravity into upper guide52d. As with lower guide42, each of the compartments54of upper guide52are in fluid communication with an outlet46, which in turn allows particulate material to travel through boom pipes48to spreader novels50. While such boom pipes48and spreader nozzles50are not shown on the right boom arm22bofFIG. 1, it is to be understood that they are provided similarly as shown on the left boom arm22a.

In an exemplary embodiment, material flow on each of the lower and upper conveyor sides36a,36b,36c,36d,38a,38b,38cand38dis independently controlled by a separate motor. In an exemplary embodiment, material moved by conveyor sides36aand38athrough lower guide42aand upper guide52aare applied to the ground surface beneath spreader20by nozzles50on boom portion24a. Similarly, material moved on lower conveyor side36band upper conveyor side38bthrough lower guide42band upper guide52b, respectively, are applied to the ground surface through nozzles50on boom portion24b. In a like manner, material moved on lower conveyor side36cand upper conveyor side38cthrough lower guide42cand upper guide52c, respectively, are applied to a ground surface through nozzles50on boom portion24c. Moreover, material moved on lower conveyor side36dand upper conveyor side38dthrough lower guide42dand upper guide52d, respectively, are applied to the ground surface through nozzles50positioned on boom portion24d. Because a rate of particulate material flow through each of the upper and lower conveyor sides36a-dand38a-dis independently controlled by a corresponding number of individual conveyor belt motors, a rate of delivery of material through each of the boom portions24a,24b,24cand24dcan be independently controlled for each of the particulate materials in compartments32and34of tank30.

Thus, in an exemplary use where spreader20navigates a left-hand turn28, the flow of material through boom portion24acan be controlled to be applied at a slowest relative rate, the flow of material through boom portion24bcontrolled to be applied at a higher speed than through boom portion24a, a rate of particulate application through boom portion24ccan be controlled to be administered at a still higher rate of speed than through boom portion24b; and a relative application rate of materials through boom portion24dcan be controlled to be at the highest speed relative to the other boom portions24a-24c.

While a particular situation is described herein, it is to be understood that the differential particulate application rates of the two materials from compartments32and34through boom portions24a-24dcan be varied to take into account other movements of apparatus20over a ground surface. Such differential speed control of the motors66a-66dand68a-68d(further described below) of lower conveyor assembly36and upper conveyor assembly38, respectively, can be automated through the use of computer controllers and global positioning system (GPS) devices. The differential application speed control through different portions24a-24dof booms22can also receive inputs from steering apparatuses and/or other input devices that sense or react to the direction and rate of travel of spreader20over a ground surface. Moreover, computer and GPS devices can be programmed to take into account the location of previous application passes so that certain motors can be turned off or their speed of application decreased, to stop or slow application through a particular one or selected boom portions24a-d, thus preventing over-application when spreader20travels over a particular parcel of the ground surface more than once. Additionally, spreader20may also be programmed or otherwise configured for map based particulate application; for example, each boom section can apply particulate material to the ground surface at a different rate based on a prescription map of the field.

While a particular configuration of spreader20is illustrated and described, having four boom sections24a-dand four corresponding sections of each of lower conveyor assembly36and upper conveyor assembly38, it is to be understood that the disclosed concepts can be readily expanded to provide for differential application rates through more or fewer boom sections or portions. Moreover, while a particular correlation of conveyor sections to boom portions is described, it is understood that the guides42,52, pipes48, nozzles50and boom portions can be set up differently to provide for other correlations between the conveyor sections and the locations of material application to a ground surface under spreader20.

While not illustrated, it is to be understood that apparatus20is typically provided with ground engaging elements such as wheels or a track that allow spreader20to travel across a ground surface in a direction generally perpendicular to the longitudinal orientation of boom22. In one typical use, spreader20is pulled behind another agricultural implement, such as a tractor. In other configurations, spreader20is self-propelled on its own chassis.

As shown inFIG. 3, in an exemplary embodiment, each of lower and upper conveyor assemblies36,38includes endless conveyor belt56,58that is configured to move (in a clockwise direction as viewed inFIG. 3) around sprocket57, roller60, drive sprocket62and tension rod64. As shown inFIGS. 2 and 4, in an exemplary embodiment, of spreader20, lower motor66acontrols the speed of particulate material moved on lower conveyor side36a; lower motor66bcontrols the speed of material conveyed on lower conveyor36b; upper motor68acontrols the speed of material moving an upper conveyor side36a; and upper motor68bcontrols the speed of material moving on upper conveyor side38b. As shown inFIG. 2, a portion of an outward conveyor56a,58ais aligned side-by-side with a portion of a corresponding inward conveyor56b,58bin a plane substantially parallel to the longitudinal axis88. While not specifically illustrated inFIGS. 1-4, it is to be understood that mirror image motor shaft assemblies70are also provided for the right side conveyor portions36c,36d,38cand38d.

FIG. 5is a cross-sectional view of two longitudinally aligned motor shaft assemblies70, as would be used for either the lower conveyor assembly36or the upper conveyor assembly38. While the components inFIG. 5are numbered for the lower conveyor assembly36, it is be understood that the motor shaft assemblies70can also be used in upper conveyor assembly38.FIGS. 2 and 4show two motor shaft assemblies70, one each on the left side of lower conveyor assembly36and on the left side of upper conveyor assembly38. It is to be understood that motor shaft assemblies70for the right side of lower conveyor assembly36and of upper conveyor assembly38are installed as mirror image structures, compared those illustrated inFIGS. 2 and 4.

As shown inFIG. 5, in an exemplary embodiment, first motor shaft74ahas a first end128aand a second end130a. First motor66ais attached to first end128aof first motor shaft74a. First motor66ais configured to rotate first motor shaft74aabout longitudinal axis88. First motor shaft74aand first motor66ahave longitudinal bore76therethrough. Second motor shaft74bhas a first end128band a second end130b. A portion of second motor shaft74bis positioned in longitudinal bore76. Second motor66bis attached to first end128bof second motor shaft74b. Second motor66bis configured to rotate second motor shaft74babout longitudinal axis88. On a right side ofFIG. 5, third motor shaft74dhas a first end128dand a second end130d. Third motor66dis attached to first end128dof third motor shaft74d. Third motor66dis configured to rotate third motor shaft74dabout longitudinal axis88. Third motor shaft74dand third motor66dhave longitudinal bore76therethrough. Fourth motor shaft74chas a first end128cand a second end130c. A portion of fourth motor shaft74cis positioned in longitudinal bore76. Fourth motor66cis attached to first end128cof fourth motor shaft74c. Fourth motor66cis configured to rotate fourth motor shaft74cabout longitudinal axis88.

Motor66ais attached to housing side wall72of spreader20(shown inFIGS. 2 and 4). Motor shaft74aof motor66acarries drive sprockets62a, which couple with endless drive conveyor belt56ain a known manner. Motor shaft74bof motor66bextends through bore76in motor66aand motor shaft74a. Second end130bof motor shaft74bis attached to bearing78, positioned on bracket80connected to housing wall132, shown inFIGS. 2 and 4. Motor66dis attached to housing side wall72of spreader20. Motor shaft74dof motor66dcarries drive sprockets62d, which couple with endless drive conveyor belt56din a known manner. Motor shaft74cof motor66cextends through bore76in motor66dand motor shaft74d. Second end130cof motor shaft74cis attached to bearing78, positioned on bracket80connected to housing wall132, shown inFIGS. 2 and 4. The use of only a single bearing78for each motor shaft assembly70reduces lubrication requirements and wear points.

In an exemplary embodiment, enough clearance is provided around second motor shaft74bthrough bore76that no physical contact is made between second motor shaft74band first motor66aor first motor shaft74a. Such an arrangement eliminates a need for bearings between motor shaft74band motor66aor its motor shaft74a. In effect, motor shaft74ais cantilevered from motor66aand is not supported on motor shaft74b. Motor shaft74bis turned by motor66band carries drive sprockets62b, on which endless belt56bmoves. Moreover, enough clearance is provided around third motor shaft74cthrough bore76that no physical contact is made between third motor shaft74cand fourth motor66dor fourth motor shaft74d. Such an arrangement eliminates a need for bearings between motor shaft74cand motor66dor its motor shaft74d. In effect, motor shaft74dis cantilevered from motor66dand is not supported on motor shaft74c. Motor shaft74cis turned by motor66cand carries drive sprockets62c, on which endless belt56cmoves. An exemplary suitable motor is available commercially from Poclain Hydraulics under compact motor model MK04. However, it is contemplated that other motors for rotationally driving a shaft are also suitable, including motors driven electrically, pneumatically, and by other methods.

As shown inFIG. 2, outward and inward conveyor belts56aand56bare separate, and outward and inward conveyor belts58aand58bare separate, and are thereby able to carry particulate material at different rates of speed. While not shown but described in this written description, inward and outward conveyor belts56cand56dare also separate, and inward and outward conveyor belts58cand58dare separate, and are thereby able to carry particulate material at different rates of speed. In an exemplary embodiment, portions of conveyor belts56a,56b,56c,56dare aligned side-by-side in a lower plane parallel to longitudinal axis88of lower conveyor assembly36; and portions of conveyor belts58a,58b,58c,58dare aligned side-by-side in an upper plane parallel to longitudinal axis88of upper conveyor assembly38.

FIG. 11shows a schematic diagram of an exemplary hydraulic circuit82for the operation of motors66a-66dfor control of the speed of material application through lower conveyor sides36a-36d, respectively. Hydraulic circuit82also shows the use of motors68a-68dfor control of material application motion rates through upper conveyor sides38a-38d, respectively. In an exemplary embodiment, the hydraulic system used in spreader20and depicted in diagram82is a hybrid of series and parallel connections for hydraulic fluid from pump84. Referring toFIG. 3, in an example, if particulate material is to be conveyed only from compartment32of tank30and not compartment34, then upper motors38a-38dwill be turned off and only lower motors66a-66dwill receive hydraulic fluid from pump84. Moreover, in an example where, with reference toFIG. 1, boom portion24ais to pass over an area of the ground that has already received an application of particulate matter, motor66acan be turned off so that fluid from pump84bypasses motor66a, thereby operating motors66b-66dto allow for application of particulate material from conveyor sides36b,36cand36dthrough nozzles50of boom portions24b,24cand24d. In an exemplary circuit82depicted inFIG. 11, a relief valve86is provided for excess hydraulic fluid that is not used by the connected motors66,68. In an exemplary embodiment, flow can be modulated through each of the motors66,68to provide for an infinitely variable speed of rotation of connected motor shafts74between off and maximum speed extremes. Thus, precise control of the rate of application of particulate material from each compartment32,34can be controlled independently at each of boom portions24a-24d.

As shown inFIG. 5, motor shaft74aand motor shaft74bare co-axial, in that they rotate about a common longitudinal axis88. Moreover, motor shaft74cand motor shaft74dare co-axial. However, the shafts are independently controlled by their respective motors66a-66dand thereby independently drive their respectively connected conveyor belt sides56a-56d. This configuration allows for independent driving of the adjacent conveyor belt sides56a,56band56c,56din a small amount of space, and with few required bearings. Independent speed control of the motor shafts74a-74dand their corresponding conveyor sides56a-56dpermit variable rate application of the particulate material conveyed thereon, as well as sectional control of the variable rate application, with application rates for the separate materials of compartments32and34at each boom portion24a-24dbeing independently controllable.

The series and bypass valve arrangements of circuit82(FIG. 11) reduce flow requirements for pump84while still allowing for independent control of each motor66a-dand68a-d. At each valve corresponding to each of the individual motors, whatever hydraulic fluid flow is not directed through that motor will flow to the next motor. In this way, all of the hydraulic fluid flow is available to each motor in each series portion of the circuit, thereby allowing for independent control of each of the individual motors. The illustrated circuit82has two parallel branches; one for lower motors66a-dand another for upper motor68a-d. With this arrangement, each of the first motors66a,68ain the parallel branches encounters a reduced pressure load, as compared to a circuit in which all of the motors are arranged in series with each other.

As shown inFIGS. 2, 3 and 6, conveyor belts56,58travel around rollers60, allowing particulate material on a top surface of conveyor belt56,58to fall into compartments44,54of guides42,52.FIG. 6shows front perspective views of the upper and lower rollers60, removed from spreader20.FIG. 7is a vertical cross-sectional view of one of the rollers60through section line7-7ofFIG. 6. As shown inFIG. 7, roller60includes shaft104having first end134, second end136, and longitudinal axis of rotation102. Inward barrel96surrounds a first portion of shaft104and is fixed to shaft104to rotate therewith. Outward barrel94surrounds a second portion of shaft104and is configured to rotate about axis102independent of a rotation of shaft104. Outward barrel94is spaced from inward barrel96along axis102. Spacer98, in block or annular form, is positioned to at least partially surround shaft102and is positioned between inward barrel96and outward barrel94.

External bearings90are provided at each of mounting brackets92. In an exemplary embodiment, each external bearing90is positioned within the respective mounting bracket92and accepts an end134,136of shaft104. Roller60includes outward barrel94, around which outward conveyor belt56a,56d,58aor58dpartially wraps and inward barrel96, around which inward conveyor belt56b,56c,58bor58cpartially wraps. Spacer98separates the outward barrel94and the inward barrel96and is formed in an exemplary embodiment of a durable polymer material. Annular bearings100, such as formed from composite materials, are provided to allow outward barrel94and inward barrel96to rotate independently about a common longitudinal access102of shaft104. An annular bearing100is positioned at least partially between the shaft104and the spacer98. In an exemplary embodiment, spacer98also serves as a seal to keep fertilizer, debris, and other material away from bearing100b. Additional seals (e.g., o-rings or lip seals) can also be integrated into spacer98to improve its performance. Moreover, annular bearing100is positioned at least partially between the shaft104and the outward barrel94.

Outward barrel94and inward96are configured to rotate independently from each other. Each of outward barrel94and inward96rotate at a speed determined by the rate of movement of its corresponding conveyor belt56a-d,58a-d, respectively. In an exemplary embodiment, common shaft104rotates on external bearings90. In an exemplary embodiment, inward barrel96is welded or otherwise fixedly attached directly to shaft104, to rotate therewith on the main external bearings90. In an exemplary embodiment, inward barrel96is substantially hollow to reduce a total weight of roller60.

Outward barrel94is free to rotate on shaft104at a different speed than inward barrel96by means of annular bearings100. In an exemplary embodiment, annular bearings100are press fit into machined recesses106on an internal surface of outward barrel94. In an exemplary embodiment, spacer98is formed of a wear resistant polymer, possibly an ultrahigh molecular weight polymer, and is located between outward barrel94and inward barrel96. Spacer98provides a seal and a wear resistant element between the barrels94,96. In the illustrated embodiment, outward annular bearing100ais positioned proximate end134and extends to mounting bracket92. This prevents particulate material from entering that end of bearing100aand also constrains motion of bearing100ain a leftward direction as viewed inFIG. 7. Moreover, spacer98prevents rightward or inward motion of outward barrel94along shaft104. In the illustrated structure, because bearings100aand100bwill wear at essentially identical rates, no angular misalignment will result from a change in the thickness of the annular bearings100a,bdue to wear. In an exemplary embodiment, annular bearings100are sealed, maintenance free composite bearings that do not require lubrication. In another embodiment, ball bearings or other bearings could be used instead of composite bearings; however, such ball bearings would require regular lubrication. While an exemplary configuration of roller60is illustrated and described, it is contemplated that roller60may be constructed differently than shown. For example, the outward barrel may be fixed to shaft104and the inward barrel may rotate independently of shaft104.

As shown inFIGS. 1, 3 and 8A-9, take-up bearing assembly108is provided near a forward end of each conveyor belt56,58and contains sprockets57, around which conveyor belts56,58travel. WhileFIG. 9is labeled for lower conveyor assembly36, it is to be understood that the descriptions also apply to upper conveyor assembly38. Outward conveyor belt56apartially wraps and travels around sprockets57a, and inward conveyor belt56bpartially wraps and travels around sprockets57b. Each of sprockets57is attached to bearing shaft110to rotate therewith. First bearing shaft110ahas first end138a, second end140a, and first longitudinal axis of rotation142a. Sprockets57aare attached to first bearing shaft110aproximate first end138aof first bearing shaft110a. Sprockets57arotate with first bearing shaft110aabout first longitudinal axis of rotation142a. Second bearing shaft110bis spaced from first bearing shaft110aby a distance D along directions112. Second bearing shaft110bhas first end138bspaced from first end138aof first bearing shaft110aby distance D and a second end140bspaced from second end140aof first bearing shaft110aby distance D. Second longitudinal axis of rotation142bof second bearing shaft110bis substantially parallel to first longitudinal axis of rotation142aof first bearing shaft110a. Sprockets57bare attached to second bearing shaft110bproximate second end140bof second bearing shaft110b. Sprockets57brotate with second shaft110babout second longitudinal axis of rotation142b.

As conveyor belts56a,56bchange in length due to wear, shafts110aand110bof take-up bearing assembly108can be moved relative to other structures of spreader20in directions112to take up slack in the respective belt or belts56a,56b. Although shafts110aand110bcan be moved independently, such movement also adjusts or changes distance D in most cases. However, it is to be understood that positional changes of both shafts110aand110bof the same amount and in the same direction may ultimately result in maintaining the same distance D between the shafts110a,110b.

Rods116pass through apertures144in plates118. Adjustment in an exemplary embodiment is accomplished by threading nuts114along rods116against mounting plates118. Providing two separate bearing shafts110a,110ballows for independent adjustment of the tension of the two conveyor belt sides56a,56b. In the illustrated embodiment, bearing shaft110arotates on bearings120amounted on rails122ain plates124a. Similarly, bearing shaft110brotates on bearings120bcarried on rails122b, which are in turn mounted on plates124b. Grooves126in top and bottom surfaces (grooves in bottom surfaces not shown) of bearing housings122allow the bearing housings122to move within rails124only in directions112.

FIG. 9is a top view of a portion of an inside of spreader20, showing the locations on which conveyor belts56a,56bwould be positioned; however, the conveyor belts themselves are not shown to allow a view of the components of take-up bearing assembly108. In the illustrated embodiments, plates124of take-up assembly108are mounted on sidewalls72of spreader20. When conveyor belts56a,56bare wrapped at least partially around their respective first and second sprockets57a,57b, a portion of the outward conveyor belt56aand a portion of the inward conveyor belt56bare aligned alongside each other in a plane substantially parallel to the axes of rotation142a,142b.

FIG. 10is a side elevation view of a second exemplary spreader220having a tank230with a single compartment therein, rather than the dual compartments32,34of spreader20. Accordingly, only a lower conveyor assembly236is used in each of the left and right sides of spreader220. In other aspects, spreader220is similar to spreader20, allowing independent control of application rates of the particulate material in tank230through four boom portions, and analogous parts are similarly labeled.

Although the subject of this disclosure has been described with reference to several embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the scope of the disclosure. In addition, any feature disclosed with respect to one embodiment may be incorporated in another embodiment, and vice-versa.