Pivot irrigation system and components

Abstract

In one example, a continuous track transport system for an irrigation system is provided that includes a continuous track and a gear train connected with the continuous track and operable to transmit an input torque to the continuous track so as to effect movement of the continuous track. The gear train includes a drive gear having an interface that is connectible to a motor of an irrigation system chassis, first and second drive wheels connected to the continuous track, each including an interface that is connectible to a corresponding interface of an irrigation system chassis, and first and second driven gears engaged with the drive gear, the first and second driven gears being mounted to respective drive wheels such that each driven gear rotates in unison with the associated drive wheel, and one or more gears of the gear train are plastic.

Claims

1. A continuous track transport system (CTTS) suitable for use in connection with an irrigation system, comprising: a continuous track that includes a plurality of grousers; a gear train connected with the continuous track and operable to transmit an input torque to the continuous track to effect movement of the continuous track, the gear train including: a drive gear having an interface that is connectible to a motor of an irrigation system chassis; first and second rotatably supported drive wheels engaged with the continuous track, each of the drive wheels including an interface that is connectible to a corresponding interface of an irrigation system chassis; and first and second rotatably supported driven gears engaged directly or indirectly with the drive gear, the first and second driven gears being concentric with the first and second drive wheels, respectively, and a rotational input to the first and second driven gears causes rotation of the first and second drive wheels, wherein one or more gears of the gear train are substantially made of plastic; and a frame to which one or more gears of the gear train are rotatably mounted.

2. The CTTS as recited in claim 1, wherein the first and second drive wheels each comprise a respective plastic sprocket.

3. The CTTS as recited in claim 1, wherein one or more of the grousers are made of plastic.

4. The CTTS as recited in claim 1, wherein a contact area defined by the continuous track is substantially the same length as the CTTS.

5. The CTTS as recited in claim 1, wherein when operated in soil, the continuous track makes a track whose width is substantially greater than a depth of the track.

6. The CTTS as recited in claim 1, further comprising first and second transfer gears, each of the transfer gears being directly engaged with the drive gear and with a respective driven gear.

7. The CTTS as recited in claim 1, wherein the drive gear and the driven gears are each mounted on respective rotatable elements that are rotatably supported by the frame.

8. The CTTS as recited in claim 1, wherein the gear train and frame both reside substantially within an envelope defined by the continuous track.

9. The CTTS as recited in claim 1, wherein the gear train is a substantially linear gear train.

10. The CTTS as recited in claim 1, wherein for a given input, a rotational speed of the drive gear is relatively less than a rotational speed of the driven gears.

11. The CTTS as recited in claim 1, wherein a substantial portion of the continuous track is made of plastic.

12. The CTTS as recited in claim 1, wherein the first and second driven gears are connected to the first and second drive wheels, respectively.

13. A portion of an irrigation system, the portion comprising: a chassis that includes a pair of hubs; a continuous track transport system (CTTS) removably connected to the chassis, and comprising: an un-tensioned continuous track that includes a plurality of grousers; a gear train connected with the continuous track and operable to transmit an input torque to the continuous track so as to effect movement of the continuous track, the gear train including: a drive gear having an interface that is connectible to a motor of the chassis; first and second rotatably supported drive wheels engaged with the continuous track, each of the drive wheels including a hub that is removably connected to a corresponding hub of the chassis; and first and second rotatably supported driven gears engaged directly with the drive gear, the first and second driven gears being connected with the first and second drive wheels, respectively, and each driven gear is configured and arranged to rotate in unison with the respective drive wheel; and a frame to which one or more gears of the gear train are rotatably mounted.

14. The portion of an irrigation system as recited in claim 13, further comprising a tower, wherein the chassis is connected to the tower.

15. The portion of an irrigation system as recited in claim 13, wherein one or more gears of the gear train are substantially made of plastic.

16. The portion of an irrigation system as recited in claim 13, wherein the first and second drive wheels are made substantially of plastic.

17. The portion of an irrigation system as recited in claim 13, wherein the continuous track is made substantially of plastic.

18. The portion of an irrigation system as recited in claim 13, further comprising: a length of pipe supported by the tower; and a pivot arm connected to the length of pipe and configured to connect to a pump station.

19. The portion of an irrigation system as recited in claim 13, wherein one or more of the grousers are made substantially of plastic.

20. A continuous track transport system (CTTS), comprising: a continuous track that includes a plurality of grousers connected to each other, each of the grousers comprising plastic; a gear train connected with the continuous track and operable to transmit an input torque to the continuous track to effect movement of the continuous track, the gear train including: a drive gear that comprises plastic; first and second drive wheels engaged with the continuous track, the first and second drive wheels each comprising plastic; and first and second driven gears comprising plastic and directly engaged with the drive gear, the first and second driven gears being concentric with, and connected to, the first and second drive wheels, respectively, and a rotational input to the first and second driven gears causes rotation of the first and second drive wheels; and a frame to which one or more gears of the gear train are mounted.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The appended drawings contain figures of some example embodiments to further clarify various aspects of the present disclosure. It will be appreciated that these drawings depict only some embodiments of the disclosure and are not intended to limit its scope in any way. The disclosure will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:

(2) FIG. 1 is a schematic plan view of an arrangement of pivot irrigation systems;

(3) FIG. 2 discloses aspects of an example tower of a pivot irrigation system;

(4) FIG. 3 discloses aspects of an example tower of a pivot irrigation system, where the tower includes a continuous track transport system;

(5) FIG. 3a discloses aspects of an example housing for a continuous track transport system;

(6) FIG. 3b discloses aspects of an example shield for a continuous track transport system;

(7) FIG. 4 is a right side perspective view of an example continuous track transport system;

(8) FIG. 5a is a left side perspective view of an example continuous track transport system;

(9) FIG. 5b is a partial left side perspective view of an example continuous track transport system, with part of the frame removed for clarity;

(10) FIG. 5c is a partial right side perspective view of an example continuous track transport system, with the motor removed for clarity;

(11) FIG. 5d is a partial section view of an example drive hub;

(12) FIG. 5e is a partial section view of an example axle hub;

(13) FIG. 6 is a top view of an example continuous track transport system;

(14) FIG. 7 is a bottom view of an example continuous track transport system;

(15) FIG. 8a is a side cutaway view showing an example interface between a continuous track transport system and a chassis of an irrigation system;

(16) FIG. 8b is a detail view of a portion of an example chain and grousers;

(17) FIG. 8c is a detail view of an example chain with grousers attached;

(18) FIG. 8d is a detail view showing an interface between two example grousers; and

(19) FIG. 9 discloses a track created by a continuous track transport system.

DETAILED DESCRIPTION OF SOME EXAMPLE EMBODIMENTS

(20) The present disclosure is generally concerned with irrigation systems and components. More specifically, at least some embodiments of the invention are concerned with an irrigation system, one example of which is a pivot irrigation system, that includes a continuous track transport system that enables the irrigation system to move throughout a field while largely, or completely, avoiding one or more of the problems associated with the use of transport systems that rely primarily on tires or wheels for movement of an associated irrigation system. Embodiments of the invention can be employed in a wide variety of applications and, accordingly, the scope of the invention is not limited to the example applications and structures disclosed herein.

(21) A. Example Configuration and Operating Environment

(22) With reference first to FIG. 1, details are provided concerning aspects of an example operating environment for at least some embodiments of the invention. In the example of FIG. 1, a pivot irrigation system 100 is indicated. In general, and as disclosed in more detail in FIG. 2, the pivot irrigation system 100 has a pivot arm 102 whose length L is defined by multiple lengths of watering pipe connected end to end and supported by a series of towers. The length L defines the radius of a circular area A that can be watered by nozzles 104 of the pivot irrigation system 100 as the pivot arm 102 rotates about a fixed point B. Water can be supplied to the pivot arm 102 by way of a supply line 106 connected to a pump station 108 that communicates with a water source (not shown). Depending upon the size of a field or area to be watered, one or more pivot irrigation systems 100 may be provided.

(23) With continued attention to FIG. 1, and directing attention now to FIG. 2 as well, further details are provided concerning the example pivot irrigation system 100. As indicated there, the pivot irrigation system 100 may include one or more towers 110, which can be constructed in the form of a metal framework. The towers 110 support the individual pipe lengths 102a and 102b that form part of the length of the pivot arm 102. Each of the pipe lengths 102a and 102b may be in fluid communication with one or more nozzles 112, which can be pendant nozzles as indicated in FIG. 2, or any other type of nozzle. With continued reference to FIG. 2, one or more of the towers 110 may include a chassis 114 that is supported by a pair of tires 116. For at least the reasons set forth elsewhere herein however, the use of tires, such as tires 116, in irrigation systems has proven to be problematic.

(24) Accordingly, attention is directed now to FIG. 3, where details concerning aspects of example embodiments of the invention are provided. The pivot irrigation system 200 may be similar, or identical, to the pivot irrigation system 100 except that instead of tires, such as tires 116, the pivot irrigation system 200 includes a continuous track transport system (CTTS), one example of which is denoted at 300.

(25) Some, none, or all portions of the CTTS and its components may be coated with paint or other materials. At least some of such materials may serve to help prevent, or reduce, rust and corrosion. Surface treatments and textures may also be applied to portions of the CTTS.

(26) Many of the elements employed in the foddering are constructed, either in whole or in part, of one or more metals. Suitable metals may include steels such as stainless steel, aluminum, and aluminum alloys, although the skilled person will understand that a variety of other metals may be employed as well and the scope of the invention is not limited to the foregoing examples. Where metal is employed in the construction of a component, the metal elements may take one or more forms including, but not limited to, square tube, rectangular tube, oval tube, polygonal tube, round tube, pipe, and solid, rather than tubular, forms of any of the foregoing. Metal elements can be extruded, forged, machined, or any of the foregoing. As disclosed in more detail elsewhere herein, materials such as plastics and rubber can be used either alone or in combination with one or more metals, in the construction of elements of the CTTS.

(27) In general, where employed as a backfit or aftermarket item, the CTTS 300 can be readily attached to the chassis 202 using the hubs (not shown) to which the tires (see 116 in FIG. 2) were formerly mounted. Of course, the CTTS 300 can alternatively be included as an element of the pivot irrigation system 200 at the time of construction of the pivot irrigation system 200. In either case, the CTTS 300 eliminates the need for tires or wheels to transport the pivot irrigation system 200 throughout a field.

(28) With continued reference to FIG. 3, and directing attention briefly now to FIG. 3a, at least some embodiments of a CTTS, such as the example CTTS 300, may include a housing 301. Among other things, the housing 301 may help to prevent the entry of foreign matter and/or other materials into various components of the CTTS, such as the gear train (discussed below). As well, the housing 301 can provide components of the CTTS with a level of protection from environmental conditions such as sun and rain. The housing 301 can be made of any suitable materials, including metal and/or plastic, for example. As well, the housing 301 may be configured to be removably attached to a frame and/or other structure of the CTTS 300. In at least some embodiments, the housing 301 includes one or more access panels 301a to enable a user to access CTTS components disposed within the housing 301 for maintenance, removal and/or repair. Further, the housing 301 may include one or more vents 301b that enable air movement through the housing 301. Finally, in addition, or as an alternative to, the access panel(s) 301a, the housing 301 may include a cover 301c, which may be hinged, that a user can open so as to access CTTS components that are disposed within the housing 301.

(29) With continued reference to FIGS. 3 and 3a, and directing attention briefly now to FIG. 3b, a shield 301d may be provided that can be used in addition, or as an alternative, to the housing 301. In general, the shield 301d can cover all, or part, of the CTTS components, such as the gear train (discussed below) for example. In this way, the shield 301d can help prevent foreign material from entering the gear train and/or other components of the CTTS. The shield 301d can be made of the same or similar materials as the housing 301, although that is not required. As well, the shield 301d can be removably attached to structural or other elements of the CTTS, with bolts or screws for example. In some embodiments, the shield 301d may include one or more access panels 301e that enable a user to gain access to components of the CTTS for inspection, repair and/or replacement, for example.

(30) B. Aspects of Some Example EmbodimentsContinuous Track

(31) With continued attention to FIG. 3, and directing attention as well to FIGS. 4-7, further details are provided concerning the example CTTS 300. As indicated in those Figures, the CTTS 300 may include a continuous track 302 that comprises a plurality of track elements, which can take the form of grousers 302a, connected together in such a way that an angle between successive grousers 302a is variable and enables one or more portions of the track 302 to assume a curved configuration, as shown in FIGS. 4 and 5 for example. In general, the example CTTS 300 may have a generally rectangular outline and, as such, may have a relatively smaller vertical dimension than triangular shaped drive systems.

(32) In at least some embodiments, one or more of the grousers 302a include one or more cleats 302b. The cleat(s) 302b, when present, can help to improve traction and soil contact of the continuous track 302 as it moves over terrain. The cleats 302b can be integrally formed with respective grousers 302, permanently attached to respective grousers 302, or may be removably attached to respective grousers 302 so that the cleats 302b can be replaced when worn, or to suit operating conditions. For example, a grouser that is suitable for use in sandy soil may not be well suited for use in clay soil.

(33) The grousers 302a and cleats 302b can be made of any suitable material, examples of which include plastic, rubber, metal, or any combination of these. Moreover, the grouser 302a and its corresponding cleat 302b can be the same material as each other, but that is not required. More generally, a cleat 302b of any of the aforementioned materials can be employed together with a grouser 302a made of any of these materials, and the scope of the invention is not limited to any particular material(s) or combination(s) thereof.

(34) In some cases, the grousers 302a can be made of recycled plastic, examples of which include, but are not limited to, the ultra-high-molecular-weight polyethylene (UHMWPE) that is sold by Quadrant Plastics under the trade name Tivar ECO. Such plastics may also be known as high-modulus polyethylene, (HMPE), or high-performance polyethylene (HPPE). Other plastics, or non-plastic materials, can alternatively be used for the grousers 302a.

(35) Finally, it will be appreciated that a variety of different continuous track 302 configurations can be defined. Thus, aspects such as the size, shape, and number of the grousers 302a can be selected as desired to define a continuous track 302 of a desired configuration. Further details concerning example grousers and an associated chain are discussed elsewhere herein.

(36) C. Aspects of Some Example EmbodimentsGear Trains

(37) As further indicated in the Figures, the CTTS 300 may include a gear train 304, part or all of which can be disposed within an envelope defined by the continuous track 302. As best shown in FIG. 6, the gears, discussed below, of the gear train 304 may all reside in substantially the same lateral plane so as to form a substantially linear gear train configuration. This configuration is provided by example only however, and other embodiments may employ a non-linear gear train configuration.

(38) In the example illustrated in FIGS. 4-7, the gear train 304 includes a drive gear 306, which can be plastic or metal, or a combination of the two. A prime mover 400, such as an electric motor for example, includes a hub 402 with a flange 402a. The prime mover 400 may be provided as part of the CTTS 300, or may be existing equipment on an irrigation system chassis to which the CTTS 300 is to be mounted. With reference to FIGS. 5d and 6 in particular, the drive gear 306 may be mounted, such as by bolting for example, to a flange 308a of a drive hub 308. The drive hub 308 further includes a flange 308b configured to be removably attached, such as with bolts for example, to corresponding flange 402a of the hub 402. In this way, the CTTS 300 can be readily attached to, and detached from, the prime mover 400.

(39) The drive hub 308, in turn, is mounted to a shaft 310, which may have a stepped configuration as shown in FIG. 5d. As discussed in further detail below, the shaft 310 may fixed to a frame 500 (discussed below) in such a way that the drive hub 308 and, thus, the drive gear 306, rotates about the shaft 310. To this end, one or more bearings 312 may be provided within the drive hub 308 to rotatably support the drive hub 308 as it rotates about the shaft 310. In one embodiment, the bearings 312 are double row tapered bearings configured to accept both axial and radial loading components. Other bearings may alternatively be employed however. In one particular embodiment, the shaft 310 is made of hot-rolled steel, such as hot-rolled steel conforming to ASTM 1018, although other materials can alternatively be employed. As well, the shaft 310 may be about 2.25 inches in diameter, and about 7 inches long, although different dimensions for the shaft 310 outside diameter and length can alternatively be implemented.

(40) In addition to the drive gear 306, and with continued reference to FIGS. 4-7, the example gear train 304 may include one or more transfer gears 314 that engage the drive gear 306. The transfer gears 314 may be substantially the same size and configuration as each other, and can be sized such that a single (1) rotation of the drive gear 306 causes >1 rotation of each of the transfer gears 314, although this configuration is provided by way of example only and is not intended to limit the scope of the invention.

(41) The transfer gears 314 can be mounted to, and rotate about, respective shafts 316. One or both of the shafts 316 can be permanently, or detachably, attached to the frame 500 (discussed below) such that the shaft 316 is fixed and the transfer gear 314 rotates about the fixed shaft 316. In one alternative arrangement, the shafts 316 can be rotatably supported by the frame 500, such as by way of bearings for example, so that the transfer gear 314 and shaft 316 rotate in unison with each other.

(42) In one particular embodiment, one or both of the shafts 316 are made of round carbon steel tube, such as carbon steel tube conforming to ASTM A-513Type 5 (1026 DOM), although other materials can alternatively be employed. One or both of the shafts 316 may be about 3.5 inches in outside diameter, and about 4 inches long, although different dimensions for the shaft 316 outside diameter and length can alternatively be implemented.

(43) As well, in one particular example embodiment, one or more transfer gears 314 are made of plastic. In this example embodiment, no bearings are required since the plastic transfer gear 314 is self-lubricating as it rotates about the shaft 316. Among other things, this bearing-less configuration eliminates a possible failure mechanism and maintenance burden, and reduces the overall weight and cost of the gear train 304. One or both of the plastic transfer gears 314 may be paired with a spacer (not shown) situated between the transfer gear 314 and the frame 500 to prevent rubbing of the transfer gear 314 on the frame 500. In alternative to this arrangement, one or both of the transfer gears 314, which may or may not be plastic, includes a bearing (not shown) that has been press fit into the transfer gear 314. This bearing can provide radial and/or axial support to the transfer gear 314 as the transfer gear 314 rotates about the corresponding shaft 316.

(44) With continuing reference FIGS. 4-7, and particular reference to FIG. 5e, the gear train 304 also includes one or more driven gears 318 that each engage a respective transfer gear 314. As well, the driven gears 318 are each connected to a respective drive wheel 320 such that an input to the drive gear 306 is transferred to the driven gears 318 and, accordingly, causes a corresponding rotation of the drive wheels 320.

(45) More specifically, an axle hub 322 is provided that includes a flange 322a to which the driven gear 318 and drive wheel 320 are bolted. In the example of FIG. 5e, the driven gear 318 and drive wheel 320 may be bolted to the left-hand side of the flange 322a, and the right-hand side of the flange 322a may be bolted to a corresponding flange of a chassis hub, as discussed elsewhere herein. In some embodiments, the axle hub 322 is made of steel that conforms to ASTM 1020, although other steels can alternatively be used. The axle hub 322, in turn, is mounted to a shaft 324, which may have a stepped configuration as shown in FIG. 5e. In one particular embodiment, the shaft 324 is made of hot-rolled steel, such as hot-rolled steel conforming to ASTM 1018, although other materials can alternatively be employed. One or both of the shafts 324 may be about 2.25 inches in diameter, and about 7 inches long, although different dimensions for the shaft diameter and length can alternatively be implemented.

(46) As discussed in further detail below, the shaft 324 may be fixed to a frame 500 (discussed below) in such a way that the axle hub 322 and, thus, the driven gear 318 and drive wheel 320, rotates about the shaft 324. To this end, one or more bearings 326 may be provided within the axle hub 322 to rotatably support the axle hub 322 as it rotates about the shaft 324. In one embodiment, the bearings 326 are configured to accept a radial loading component. Other bearings may alternatively be employed however.

(47) Because the drive wheels 320 are each engaged with the continuous track 302 (see, e.g., FIG. 8b), rotation of the drive wheels 320 causes a corresponding movement of the continuous track 302, namely, clockwise in the example of FIGS. 5a-5c. In at least some embodiments, one or both of the drive wheels 320 take the form of a sprocket. The sprocket can be made of plastic and, in one particular example embodiment, is in the range of about 14 inches to about 18 inches in diameter, with a thickness in a range of about of an inch to about 1 inches. In one more particular example, the sprocket is about 16 inches in diameter, and about 1 inch thick. The foregoing are presented only by way of example however, and the scope of the invention is not limited to these dimensions or associated aspect ratios. As in the case of the drive wheels 320, one or both of the driven gears 318 can be partly, or completely, made of plastic, although that is not required. More generally, at least the diameter and/or size and number of teeth of any combination of the gears in the gear train 304 can be varied as desired to achieve a particular gear ratio and/or other effects.

(48) As best shown in FIGS. 5a-5c, the design and configuration of the gear train 304 is such that both of the transfer gears 314 and drive wheels 320 rotate in the same direction, for a given output direction of the drive gear 306. It can likewise be seen that a range of variations can be implemented to the CTTS 300. Thus, in some embodiments, at least some of the gears of the drive train 304 can be omitted.

(49) For example, the transfer gears 314 can both be omitted, and the drive gear 306 directly connected, or coupled by a chain or toothed belt for example, to the driven gears 318. With this configuration, the CTTS 300 will still implement a desired rotation of the drive wheels 320. Another aspect of this configuration is that the overall length of the gear train 304 is shortened and this, in turn, can enable a relatively shorter track 302 and correspondingly smaller soil contact area. This smaller soil contact area may be desirable where, for example, the CTTS 300 is used with a relatively small tower.

(50) An another example of a modification that could be made to the drive train 304, the driven gears 318 could be omitted, and the transfer gears 314 each mounted to a respective axle hub 322, along with a respective drive wheel 320, and engaged directly, or by a chain or toothed belt, with the drive gear 306. In this arrangement, the direction of rotation of the drive wheels 320 would be opposite that indicated in FIGS. 5a-5c, assuming that the input provided by the drive gear 306 is the same as shown in FIGS. 5a-5c.

(51) In yet another modification to the drive train 304, one transfer gear 314 and the associated driven gear 318 can be omitted, leaving only a single transfer gear 314 and associated driven gear 318. In this example arrangement, the input from the drive gear 306 is thus directed only to one of the drive wheels 320 and the other drive wheel 320 is only connected to the drive gear 306 by way of the track 302.

(52) While the foregoing example modifications to the gear train 304 concern the omission of one or more gears, yet other modifications can be made to the drive train 304 that involve the addition of one or more gears. For example, one or more gears can be added so as to effectively increase the overall length of the gear train 304 and, correspondingly, the length of the track 302 and the soil contact area.

(53) It will also be apparent from FIGS. 5-7 that a desired output rotational speed of the driven gears 318, transfer gears 314, and drive wheels 320 can be obtained by selection of suitable gear sizes and arrangements of gears. With reference to the illustrative example of CTTS 300, the drive gear 306 is larger in diameter than either of the transfer gears 314 and the driven gears 318. Thus, a relatively low rotational speed input (which can be expressed as revolutions per minute, or RPM) to the drive gear 306 will result in a relatively higher rotational speed of the transfer gears 314, driven gears 318 and drive wheels 320. In this example, the transfer gears 314 not only convert the rotational motion of the drive gear 306 to a rotational motion of the driven gears 318, but also increase the rotational speed of the driven gears 318 relative to the rotational speed of the drive gear 306.

(54) With the foregoing points in view, and with continued reference to FIGS. 5a-5c and FIGS. 6-7, one particular example embodiment of the drive train 304 includes gears of various specific sizes. More particularly, in this example embodiment, a drive gear 306, two transfer gears 314 and two driven gears 318 are provided. In this example, the drive gear 306 has a pitch diameter of about 16 inches and 32 teeth, the transfer gears 314 have a pitch diameter of about 13 inches and 26 teeth, and the driven gears 318 have a pitch diameter of about 8 inches and 16 teeth. The foregoing relations between pitch diameters and teeth can be used to select gears of yet other pitch diameters and tooth counts. However, the scope of the invention is not limited to the foregoing example nor to the foregoing relations and, accordingly, any other suitable gear configurations and relations can be employed.

(55) As the foregoing discussion makes clear, movement of the continuous track 302 can be effected with a wide variety of different CTTS gearing arrangements and gear train configurations. Accordingly, the scope of the invention is not limited to the example arrangements and configurations disclosed herein.

(56) In connection with the foregoing, it should be noted that any of the gears within the scope of this disclosure can be constructed of a variety of different materials. Thus, and in general, any of the disclosed gears, in any combination, can be made of plastic, or metal, for example. That is, any combination of one or more of the drive gear 306, transfer gears 314, driven gears 318, and drive wheels 320 may be made of plastic, or metal. Moreover, a gear train may include plastic gears exclusively, or metal gears exclusively, or may include a combination of plastic gears and metal gears. Metals that can be used in the construction of metal gears include, but are not limited to, steel, steel alloys, aluminum, and aluminum alloys.

(57) In at least one embodiment, all the gears of the gear train are plastic. As discussed in more detail below, the plastic may be the same for each gear, or different types of plastic may be used in two or more different gears. Although, as discussed below, plastic gears may be advantageous in certain circumstances, they need not be used in all embodiments, or in any embodiment.

(58) Lighter weight gear materials, such as plastic, for example, may be particularly useful in at least some applications as such materials can help reduce the overall weight of the CTTS, and also reduce the load imposed on the prime mover 400. Plastic gears may also be desirable due to their resistance to rust, corrosion, galling, seizing and other problems that may sometimes be associated with the use of certain metals and combinations of metals. Plastic gears may also be more weather resistant than metal gears. For example, some embodiments of plastic gears may include an additive or other material(s) that make the plastic gear resistant to ultraviolet (UV) light.

(59) As well, plastic gears are relatively light and inexpensive when compared with steel gears of comparable dimensions and configurations. For example, some types of plastic are only about 1/7 the weight of steel. As well, plastic gears can be molded and thus avoid at least some processes, such as casting, for example, sometimes associated with the construction of metal gears. Moreover, any of the gears disclosed herein, whether plastic or metal, can include one or more lightning holes to achieve a further reduction in weight.

(60) It should also be noted that where a gear train such as gear train 304 includes more than one plastic gear, different plastics can be used for different gears. For example, and with reference to two gears engaged with each other, one of the gears may be made of a first type of plastic and the other of the two gears may be made of a second type of plastic that is different from the first type of plastic. Depending upon the plastics selected, such a plastic-to-plastic engagement arrangement can enable a relative reduction in wear and friction as compared with an arrangement where both plastics are the same, or an arrangement where one gear is plastic and the other gear is metal.

(61) The disclosed plastic gears can be formed by any of a variety of processes, or combinations of processes. Example production processes for plastic gears include, but are not limited to, any one or more of injection molding, extrusion, rotational molding, and blow molding. As well, the plastic gears can be cut from stock and then machined using methods such as turning, milling, drilling, shaping, and hobbing. A variety of factors can inform the design and production of the gears, whether made of plastic or other material(s). Examples of such factors include weather, soil types, humidity, topography, desired weight of the gear train, cost, friction properties, and reliability.

(62) With the foregoing in view, following is a brief discussion of example plastics that can be used in the construction of various components of a gear train, one example of which is the gear train 304. For example, the drive wheels, driven gears, drive gear, and skids, or any combination of the foregoing, can be made of the same type of plastic. One example of such a plastic includes any plastic from the family of synthetic polymers known generically as aliphatic polyamides, and sometimes sold under the trade name nylon.

(63) In a more particular example, an aliphatic polymide that contains finely divided particles of molybdenum disulphide (MoS.sub.2) may be especially well suited to some applications. One such plastic is sold by Quadrant Plastics under the trade name Nylatron GSM. The presence of the MoS.sub.2 may serve to enhance the load bearing capabilities of this plastic, while maintaining the impact resistance that is characteristic of aliphatic polymides.

(64) Yet other components of one or more embodiments of a drive train may be made of a different plastic. For example, the transfer gears may be made of polyoxymethylene (POM). POM is a thermoplastic that can be used in parts that require high stiffness, low friction, and dimensional stability. It should be noted that POM is sometimes referred to as acetal, polyacetal, or polyformaldehyde. As well, POM may be sold under trade names such as Delrin, Celcon, Ramtal, Duracon and Hostaform, for example.

(65) As the foregoing makes clear, a variety of different plastics can be employed in different embodiments of the invention. Accordingly, the scope of the invention is not limited to the use of any particular plastic, or combination of plastics.

(66) D. Aspects of Some Example EmbodimentsFrame

(67) With continued reference to FIGS. 4-7, at least some embodiments of the CTTS 300 include a frame 500. The frame 500 may include a support arm 502 that supports respective shafts, discussed elsewhere herein, to which the drive gear 306, transfer gears 314, and driven gears 318 are mounted, as shown in FIGS. 5a-5c for example. In general then, the support arm 502 may support shaft 310, one or more shafts 316, and one or more shafts 324.

(68) In at least some embodiments, the support arm 502 includes an array of pre-formed holes that enable a user to define a desired gear train 304 configuration. By way of example, the support arm 502 can include a plurality of openings, such as four or more, for example, which are each configured to receive a shaft 324. In this way, a user can position a shaft 324 in a variety of different locations and thereby customize the gear train configuration 304 to suit a particular need or application. Additionally, or alternatively, and as illustrated by the example of FIG. 5a, the support arm 502 can include one or more slots 502b, which can be vertically, horizontally, or angularly, oriented. Such slots 502b enable a shaft to be slid into a desired location, thereby permitting ready customization and/or adjustment of a drive train 304. Such slots 502b can include a plurality of cutouts 502c configured to receive a portion of a shaft, where each of the cutouts 502c defines a different respective shaft position. A locking bar not shown or other structure(s) can be used to retain a shaft in a particular cutout 502c until it is desired to remove the shaft from that cutout 502c.

(69) With continued reference to FIGS. 4-7, further details will now be provided concerning the example frame 500. As shown in the Figures, a plurality of vertical support members 504 are connected to the support arm 502. Each of the vertical support members 504 rests on a respective cross-piece 506 that rests on a pair of parallel base members 508. One, some, or all of the support member 502, vertical support members 504, cross-pieces 506, and base members 508 may be in the form of tube or pipe, or may be in the form of a solid member. The various pieces and members of the frame 500 can be permanently, or removably, attached to each other in any suitable manner, such as, but not limited to, bolting, welding, or brazing, or any combination of the foregoing.

(70) In at least some embodiments, the support arm 502, the support members 504, and/or the cross-pieces 506, or any combination of the foregoing, may be made of cold-formed carbon steel, such as the cold-formed carbon steel conforming with the ASTM A 500 specification, although other materials can alternatively be employed. In one particular embodiment, the cross-pieces 506 are 2212 (long) square tube, although other sizes and configurations of materials can alternatively be used. In the same embodiment, and/or in other embodiments, the support arm 502 is 2656 (long) rectangular tube, although other sizes and configurations of materials can alternatively be used. In yet other embodiments, one or more components of the frame 500, such as the support arm 502, for example, may be made of plastic, such as any of the plastics disclosed herein.

(71) As best shown in FIGS. 4 and 5a-5c, some embodiments of the base members 508 are configured and arranged so that the base member 508 serves as a rub rail for the grousers 352 (and/or 302a) as the grousers 352 move underneath the base member 508. As well, the contact piece 508a can serve as a chain guide that limits, or prevents, lateral movement of the chain 360 (discussed below). The contact piece 508a may be made of a relatively rigid material that can support the weight of the gear train 304, but which is sufficiently soft that it does not cause undue wear on interior surfaces of the grousers 302a that it contacts. As well, the material of the contact piece 508a may be a relatively low-friction material. Examples of such materials for the contact pieces 508a include, but are not limited to, solid fluorocarbons such as polytetrafluoroethylene (PTFE) which may be sold under the Teflon mark, and thermoplastics such as polyoxymethylene (POM) which may be sold under the Delrin mark.

(72) E. Aspects of Some Example EmbodimentsIrrigation System Chassis

(73) With reference briefly now to FIG. 8a, details are provided concerning an example interface between a system such as the CTTS 300 and a chassis 600 of an irrigation system, such as a pivot irrigation system, for example. The chassis 600 may be the same as, or similar to, chassis 114 (see FIG. 2), or may have another configuration.

(74) In the example of FIG. 8, the flanges 322a of the axle hubs 322 of the CTTS 300, or another CTTS, are configured and arranged to be connected with corresponding chassis hubs 602 of the chassis 600. More particularly, the flanges 322a of the axle hubs 322 can be bolted, or otherwise attached, to flanges 602a of the chassis hubs 602. As a result of this configuration of the CTTS 300, it can be readily attached to, and detached from, the existing hubs of an irrigation system chassis. This configuration thus enables ready replacement of irrigation system tires with a CTTS, and also enables ready removal of the CTTS from the irrigation system chassis, should there be a need to do so. Of course, the scope of the invention is not limited to the use of hubs and/or flanges. More generally, any other structure(s) that enable ready attachment and detachment of a CTTS to/from an irrigation system chassis can alternatively be employed.

(75) Turning now to FIGS. 8b-8d, details are provided concerning a particular example of a grouser and chain configuration that can be used in at least some embodiments. In the example of FIGS. 8b-8d, the track is denoted generally at 350 and includes a chain 360 that engages a drive gear in the form of a sprocket 370. Example aspects of a sprocket, such as sprocket 370, are disclosed elsewhere herein. In general however, the sprocket 370 may include a plurality of teeth 372 where successive teeth are separated by spaces 374 that successively engage corresponding pins 362 of the chain 360. The pins 362 also secure successive links 364 of the chain 360 to each other. In the example of FIGS. 8b-8d, the links 364 are metal, although that is not required. In other embodiments, the links 364 can be plastic and connected to each other with pins, which may be metal.

(76) As best shown in FIG. 8b, each of the links 364 may define one or more holes 364a which can accommodate a respective fastener 366, such as a bolt, screw or rivet for example, for releasably fastening a grouser 352 to the link 364. As indicated in FIG. 8d, the configuration and arrangement of the grousers 352 and links 364 is such that adjacent grousers 352 can change their angular position relative to each other.

(77) In at least one example embodiment, the links 364 and grousers 352 may both be plastic. In yet another example embodiment, the links 364 and grousers 352 can be integrally formed with each other. That is, a link 364 and associated grouser 352 may take the form of a single piece of material, such as plastic, for example, and the links 364 joined to each other with metal or plastic pins.

(78) F. Operational Aspects of Some Example Embodiments

(79) In general, the operation of a CTTS is similar to tires in that the CTTS is able to transport an irrigation system through a field. However, and with attention finally to FIG. 9, it can be seen that the CTTS may resolve a number of problems typically associated with the use of tires in irrigation systems such as pivot irrigation systems.

(80) In particular, and as indicated in FIG. 9, it can be seen that a conventional tire 700 of an irrigation system creates a relatively wide and deep track 702 profile in the soil. The creation of such tracks 702 is problematic for reasons stated elsewhere herein. Moreover, the pressure exerted by the tire(s) 700 on the soil is relatively large because the contact area 704 between the tire 700 and soil is relatively small.

(81) In contrast, a continuous track 800, such as may be used in embodiments of a CTTS, creates a relatively wide, but shallow, track 802 in the soil. For at least the reasons explained elsewhere herein, the track 802 is significantly less problematic than the track 702. This track 802 profile is at least partly a result of the fact that the pressure exerted on the soil by the continuous track 800 is relatively low, at least in comparison with the tire 700 which is typically employed on many irrigation systems. The low pressure is, in turn, a function of the relatively large contact area 804 between the continuous track 800 and the soil.

(82) G. Operational Aspects of Some Example Embodiments

(83) With reference to FIGS. 4-7 and 9, example embodiments of the CTTS operate generally as described hereafter. In particular, an input torque applied to a drive gear, such as drive gear 306, by a prime mover, such as prime mover 400, causes operation of a gear train, such as gear train 304. Operation of the gear train causes the rotation of a pair of drive wheels, such as drive wheels 320, which in turn, causes the rotation of a continuous track, such as continuous track 302, that is connected to the drive wheels. The motion of the continuous track causes the movement of an associated portion of an irrigation system through a field. As the irrigation system moves through the field, a track profile, such as the track 802, may be created. In some instances, the soil and field conditions may be such that a very small, or no, track is created by the CTTS.

(84) H. Useful Aspects of Some Example Embodiments

(85) As will be apparent from the disclosure, one or more embodiments of the CTTS can provide one or more advantageous and unexpected effects, in any combination, some examples of which are set forth below. It should be noted that such effects enumerated herein are neither intended, nor should be construed, to limit the scope of the claimed invention in any way.

(86) One useful aspect of some embodiments of the invention is that such embodiments do not create the wide and deep tracks that commonly result from the use of tires or wheels on movable irrigation systems. Consequently, the soil erosion and related problems typically associated with the use of such tires or wheels may be reduced, or avoided, by use of a CTTS.

(87) Another useful aspect of some embodiments of the invention is that the maintenance and cost burdens associated with the use of tires and wheels may be reduced, or eliminated by the employment of a CTTS.

(88) Although this disclosure has been described in terms of certain example embodiments, other embodiments apparent to those of ordinary skill in the art are also within the scope of this disclosure.