SUSPENSION MECHANISM FOR AGRICULTURAL ROW UNIT

Abstract: A precision seed drill row unit (10) comprises a seeding unit (20) mounted on a toolbar (12) by a suspension mechanism (14) comprising sliding forks (34, 36) whereby contour following under the action of soil-engageable wheel (16) is damped by sliding friction in the forks so as to produce a more balanced contour following action.

Description: SUSPENSION MECHANISM FOR AGRICULTURAL ROW UNIT This invention relates to suspension mechanisms for row units of agricultural and horticultural implements such as row units for seeding implements, for example precision drills for sowing row crops such as vegetables, cereals and the like. Row units for precision seed drills of the kind used for vegetables and cereal seed sowing are usually mounted on a toolbar which is itself provided with a headstock whereby it is fully mounted on the hitch links of a tractor. The row units are supported by the toolbar in their transport position, and are drawn by the toolbar and receive drive from a transmission associated with the toolbar during seeding operations. Various other arrangements are possible, but the latter is fairly conventional. Conventionally, seed drill row units comprise a seeding unit for selecting and dispensing seeds from a supply, and the seeding unit is supported relative to the ground on a frame having front and rear wheels. Various arrangements have been proposed for SUBSTITUTE SHEET mounting the seeding unit -in relation to the front and rear wheels of the row unit and for mounting the row unit on the toolbar itself. Such proposals include the use of freely pivoted linkages for transmitting draught forces, and indeed for supporting the row unit during transport. The shortcomings of these prior proposals include a ' tendency to- vibrate, and unsatisfactory soil contour following, for the purpose of maintenance of constant seeding depth. Depending on the geometry of the pivoted linkages provided, « the seeding unit has a tendency to under or over¬ react to soil contour changes encountered. There is thus a need for apparatus providing a more balanced response to commonly occurring drilling conditions. An object of this present invention is to provide a suspension mechanism suitable for a row unit of an agricultural or horticultural implement offering improvements in relation to one or more of the matters discussed above, or generally. According to the invention there is provided a suspension mechanism for a row unit of an agricultural or horticultural implement as defined in the accompanying claims. In an embodiment of the invention described below, a suspension mechanism for a row unit of an agricultural precision seed drill has connection means to apply draught forces to the soil-engagable row unit while permitting contour following by the row unit. The suspension mechanism comprises sliding suspension elements. These suspension elements extend upwardly from a soil-engaging wheel of the row unit to an upper draught connection means for the row unit. Height-adjustable connection means is provided to connect the suspension mechanism to the soil-engagable seed unit. This connection means maintains the attitude of the seed unit substantially constant at all adjusted positions. In one embodiment the connection means comprises a parallelogram linkage. In another embodiment it comprises an upwardly extending guide and a slidable member received thereon, together with fixing means to fix the slidable member in a chosen position. The sliding suspension elements are in the form of telescopic elements received one within the other. Two pairs of telescopic suspension elements are provided, one pair at each side of the soil-engaging wheel. The pairs of suspension elements are arranged in the manner of the front fork suspension assembly of a two-wheel road vehicle, such as a motorcycle. The suspension elements extend upwardly and rearwardly (with respect to the normal direction of for ard motion of the drill) from the soil ■engaging wheel. The attitude of the suspension elements is from 90 degrees to 45 degrees with respect to the horizontal, preferred inclinations being from 90 degrees to 30 degrees and 10 degrees to 20 degrees. In the embodiment, the inclination is from 14 degrees to 16 degrees. In the embodiments, resilient means is provided to enhance penetration by the coulter of the seed unit and to increase the damping effect on contour following of the seed unit. In one embodiment, a coiled compression spring acts between the sliding suspension elements. " In another embodiment a torsion spring acts between a relatively fixed portion of the drill and the lower of the two sliding suspension elements. In both cases upward movement of the seed unit is resilient ly resisted. In the embodiments, damping is provided to resist relative movement of the sliding suspension elements. The damping means arises from frictional forces associated with sliding movement of the suspension elements. The geometry of the suspension assembly is such that the frictional damping of the assembly- varies according to the magnitude, of the ground contour engaged by the soil engaging front wheel. The upper of the two sliding suspension elements is secured by a bracket to the toolbar of the seed drill. In use, the toolbar is height- controlled by land wheels. These wheels drive the seed units through a transmission system extending lengthwise of the toolbar. The transmission system comprises inter-fitting transmission elements extending lengthwise of the toolbar and serving to couple together and to couple to the land wheel drive, a series of pulleys, one for each row unit. The transmission elements are preferably of the male and female kind providing sliding length adjustment. In the embodiment a dog-and-bone coupling system is provided whereby individual portions of the transmission can move out of axial alignment with other portions while still transmitting drive thereto or therefrom. The pulleys in the system are individually mounted on swing able mounting arms which are spring loaded to tension the drive belts-oOugxldd thereto. These belts train smit drive to the seed units. Swinging motion of the pulleys is accommodated by the dog- and-bone transmission system. Such swinging movement itself accommodates contour following movement of the seed units arising from sliding of the suspension elements. As an alternative to frictional damping of the sliding suspension elements, additional damping may be provided by hydraulic or other damping devices of various kinds, including conventional hydraulic dampers. In the .embodiment , the soil engaging wheel connected to the suspension elements is the front or leading wheel of the row unit having regard to the direction of normal forward motion. A rear press wheel is mounted on the row unit. The press wheel is not mounted on the seed unit. It is pivot lly connected to the upper end of the suspension assembly, whereby it does not affect c ont our f ol lowing . A relatively narrow seed press wheel is mounted on the seed unit by a novel mounting assembly whereby the seed press wheel is effectively castored. The mounting arrangement for the seed press- wheel comprises a slotted mounting arrangement permitting lateral movment while setting up restoring forces due to the resulting offset line of draught, thereby giving a castor action which is assisted by soil forces. Such a self- castoring seed press wheel arrangement is of benefit for all kinds of precision seed drills and a further aspect of the invention relates to the provision of such a wheel for a precision seed drill of any kind. The invention also provides a suspension mechanism for a row unit of an agricultural implement comprising any novel feature of concept, or novel combination of features or concepts disclosed herein. Embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which: Fig 1 shows a side elevation view of a row unit of a precision seed drill according to the invention; Fig 2 shows a perspective view of a second embodiment of a seed drill according to the invent ion ; Fig 3 shows a side elevation view of the embodiment of Fig 2, with certain minor detailed differences; Fig 4 shows a plan view of the embodiment of Fig 3; and Figs 5 and 6 show on a larger scale, views generally in the direction of Arrow V in Fig 3, illustrating the construction of a dog-and-bone drive arrangement. - 9 - As shown in Fig 1 of the drawings, a row unit 10 of a precision seed drill is mounted on a toolbar 12 by a suspension mechanism 14. Row unit 10 comprises soil-engagable wheels 16, 18, a seeding unit 20 having a coulter 22 and a hopper 24. Seeding unit 20 is connected to suspension assembly 14 by a parallelogram linkage 26 comprising upper and lower links 28, 30. Rear wheel 18 is in the form of a press wheel mounted on a rearwardly extending arm 32 fixed to seeding unit 20 at a pre-set attitude. The attitude of parallelogram linkage 26 relative to seeding unit 20 can be adjusted by a screw threaded adjuster (not shown) whereby the height of coulter 22 relative to front wheel 16 can be adjusted. Seeding unit 20 comprises a suitable seed selection mechanism (not shown) . Suspension mechanism 14 comprises sliding suspension elements 34, 36. Suspension element 34 comprises a rod adjustably secured to a bracket assembly 38 fixed by bolts 40 to toolbar 12. Rod 34 is height-adjustable relative to bracket assembly 38 by means of adjustment bolt 42 and associated nuts. The lower sliding suspension element 36 is in the form of a tube having ears 44 , 46 , 48 to receive pins providing the journal axis of front wheel 16 , and of upper and lower links 28, 30. Suspension rod 34 is slidable in a ' collar 50 fixed to the upper end of suspension tube 36. At the lower end of rod 34 a second collar 52 is fixed to rod 34 and slides in suspension tube 36. A spring clip 54 is received in a shallow groove on rod 34 to limit downward movement of tube 36. An outer collar 56 has a dust ring 58 and locks the assembly in position. A second suspension assembly, substantially identical to assembly 14 is provided on the other side of front wheel 16 , and is likewise connected to seeding unit 20 by a second set of parallel links and corresponding related components. A soil deflector 60 is mounted between the suspension assemblies by means of a generally U-shaped arm 62. A centre seed press wheel (not shown in Fig 1) is mounted on seed unit 20 to consolidate the narrow line of individual seeds placed by the seed unit In use, suspension elements 34, 36 execute sliding movement relative to each other to accommodate soil contours. This sliding movement oCffi'UEB between sleeve 52 and the inner surface of tube 36, and between rod 34 and collar 50. Fig 1 shows the nominal normal working position of the assembly with spring clip 54 positioned so as to permit downward movement of wheel 16 until the spring clip reaches collar 50. Likewise, upward movement of the wheel is permitted until collar 56 engages bracket 38. Toolbar 12 is at a fixed height as determined by the land wheels (not shown) . This effectively determines the height of rod 34. Tube 36 and wheel 16 move up and down relative to rod 34 in accordance with ground contours. Such movement is transmitted through the fixed linkage 26 to seed unit 20, whereby the latter follows ground contours also. Thus, suspension mechanism 14 serves to transmit draught forces to seed unit 20 while providing for friction -damped contour following of the wheel and seed unit as determined by relative sliding movement of the elements of the suspension assembly. It will be appreciated that when front wheel 16 encounters a bump in the soil, the larger the bump or contour, the higher.- -will be the position at which it initially makes contact with wheel 16 , and hence the more rearwardly directly (rather than upwardly directed) will be the component of force acting on the suspension assembly and arising from the impact. Hence, the frictional damping force exerted between the sliding suspension elements 34, 36 will increase with increasing height of a soil contour encountered, and thus the damping effect will correspondingly increase. In this way, a balanced reaction to soil contours is obtained, whereby a much more uniform seeding depth may be achieved. In the embodiment of Figs' 2 to 6 , parts corresponding to the embodiment of Fig 1 are identified by the same reference numeral increased by 100 so that, for example, front wheel 16 in Fig 1 becomes wheel 116 in Fig 2. It will be noted that there are minor differences of structure between the apparatus shown in Figs 2, 3 ,and 4. Except where specifically commented on in the description below, these differences are of no particular significance, and Figs 2 to 6 are treated as a single embodiment. This embodiment is constructed and arranged and operates as described above with reference to Fig 1, except as follows. The arrangement of toolbar 112, brackets 138- and upper fork members 134, is generally as in Fig 1. Lower fork members 136 are in this embodiment arranged on the forward side of the axis of front wheels 116, but at the same angle of 15 degrees with respect to the vertical. In place of the parallel links 28, 30, each suspension assembly 114 comprises a fixed upper link 129 secured to tube 136, and a lower link 131. An upwardly extending guide rod 133 is secured by bolts to the ends of links 129 and 131 so as to be in a fixed attitude with respect to tube 136. Seed unit 120 is adjustably secured to guide rod 133 by means of an adjustable sleeve 135 received thereon and which may be fixed by means of a screw clamp 137 having a hand lever 139. Lengthwise adjustment of the seed unit with respect to guide rod 133 is effected by means of a screw mechanism comprising a threaded rod 141 which co-operates with a trunnion 143 at the upper end of guide rods 133. Threaded rod 141 is connected to seed unit 120 so as to adjust same lengthwise of guides 133 by rotation of the rod 141. Such adjustment is effected without any attitude change of the seed unit. When the height of the latter has been chosen, it is clamped by means of hand lever 139. Drive to seed unit 120 is derived from land wheels (not shown) through a transverse transmission system including pulleys 170, 172 and belts 174. Figs 5 and 6 show details of the structure of the transmission system 176, also seen in Fig 2. Broadly, it is of the dog-and-bone kind in which the bones 178 have hexagonal end formations 180 mounted on a rod 182. The end formations are received in a complementary hexagonal-section tube 184 of bones 186 and are retained by spring clips 188, thereby providing a length-adjustable drive transmission. Each of the bones is mounted through bearings 190 on an arm 192 pivotally connected to the brackets 138 on toolbar 112. Pulleys 170 are formed at either end of the bones according to choice. Torsion springs 194 mounted on arms 192 and acting between fixed links 129 and brackets 138 serve to tension belts 174 and apply downward loading to tubular suspension elements 136. A seed press wheel 200 is connected to seed unit 120 by mounting links 202 having lengthwise slots 204 receiving a connection pin 206 whereby lateral swinging movement of the press wheel is permitted and thereby giving it a self -re turning castoring action under the effect of restoring forces. Rear press wheel 118 is freely trailed from brackets 138 on mounting arm 132 which may have either of the forms shown in Fig 3. As shown in Figs 2 and 3, the rear press wheel is mounted on forks 208 formed with end slots 210 whereby the press wheel can be quickly detached in order to substitute a press wheel of different profile. The press wheel has internal weights 212 secured within its dish structure, and has a rear scraper 214. Covering blades 216 ahead of the rear press wheel are adjustable both for angle of inclination and depth. In use, this embodiment operates substantially as that of Fig 1 , with the exception of the manner of setting the height of seed unit 120 with respect to forward wheel 116 by means of threaded adjuster "1 -• 141. Obviously, many modifications can be made in the above embodiments while remaining within the scope of the invention, including substitution of any suitable sliding arrangement of suspension elements and different modes of connecting the seed unit and the remainder of the row unit to the suspension and front wheel assembly. Also, provision for even greater damping may be provided by means of conventional damper units, or indeed by provision of resilient.' means on the suspension assembly, including the possibility of providing coiled springs in or on the suspension units, perhaps in the manner of motor cycle front orks . A single fork or suspension assembly could be provided for each wheel. Obviously, any form of seed unit (or indeed other suitable agricultural mechanism) could be connected to the guide rods 133 so as to be drawn and caused to contour-follow by the suspension assembly. Seed press wheel 200 could be used on any form of precision or other drill requiring it. Indeed the castor action mounting of wheel 200 may well be applicable to other agricultural and horticultural ground-engaging rotary elements without limitation, and these aspects of the mounting may be claimed in due course. The self-return action arises from the unbalanced draught applied to the mounting as soon as the wheel moves from dead centre so that one end of the pin disengages from .the front end of the corresponding slot.

Claims: CLAIMS 1 A suspension mechanism for a row unit of an agricultural implement , said suspension mechanism having connection means to apply draught forces to a soil engagable unit of the row unit while permitting contour following by said soil engagable unit, characterised in that the suspension meehanism comprises sliding suspension elements. 2 A suspension mechanism according to claim 1 characterised in that the suspension mechanism interconnects and extends upwardly between a soil- engaging wheel and an upper draught connection means for the row unit. 3 A suspension mechanism according to claim 1 or claim 2 characterised by said connection means comprising adjustable means for height -ad just ably connecting a soil engagable unit thereto while maintaining the attitude of the soil engagable unit with respect to the ground substantially c on st ant , 4 A suspension mechanism according to claim 3 characterised in that said adjustable connection means comprises upwardl -extending guide means and a slidable member received thereon, together with fixing means for fixing the position of said slidable member relative to the guide at a .chosen location. 5 A suspension mechanism according to any one of the preceding claims characterised in that said sliding suspension elements comprise telescopic suspension elements received one within the other. 6 A suspension mechanism according to claim 5 characterised in that two pairs of telescopic suspension elements are provided, one pair at each side of a soil engaging wheel. 7 A suspension mechanism according .to claim 5 or elaim 6 characterised in that said suspension element extends upwardly and rearwardly in the normal working position of the mechanism, the handle of the suspension elements with respect to the vertical being between 0 degrees and 45 degrees. 8 A suspension mechanism according to claim 7 characterised in that the angle of said suspension elements with respect to the vertical lies between 0 degrees and 30 degrees. 9 A suspension mechanism according to any one of the preceding claims characterised by resilient means connected between said sliding elements to resist relative sliding movement in the direction caused by convex ground contour s in use . 10 A suspension mechanism according to any one of the preceding claims characterised by a press whee l pivot ally connected to the upper one of said sliding elements for transmission of draught forces .

Inventors: HOLLAND SIMON JEFFREE ROY, HOLLAND, SIMON, JEFFREE, ROY
Applicants: HESTAIR FARM EQUIP LTD, HESTAIR FARM EQUIPMENT LIMITED
Application year: 1985
Main classification: A01C5
IPC codes: A01B39, A01C5, A01C7