NZ191458A - Precision seeder for depositing evenly spaced single seeds in furrow - Google Patents

Description

NEW ZEALAND PATENTS ACT, 1953 No.: 191,458 Date 3 September 1979 t ( i 25 /:, :.d i :■ COMPLETE SPECIFICATION "PRECISION SEEDER" lx/We, DEVELOPMENT FINANCE CORPORATION OF NEW ZEALAND, established by the Development Finance Corporation Act 1964 and reconstituted by the Development Finance Corporation Act 1973, of Development Finance Centre, Corner Grey and Featherston Streets, Wellington, New Zealand, hereby declare the invention for which fc/ we pray that a patent may be granted to awe/us, and the method by which it is to be performed, to be particularly described in and by the following statement: - l^H59 This invention relates to a precision seeder. The expression "precision seeder" as used herein relates to a seeding device able to deposit single seeds at predetermined spacings in seed beds but also includes the capability of planting seeds at predetermined spacings in unprepared soil.

The present specification relates to the use of a seeder in the planting of pinus radiata seeds to produce seedlings in specially prepared seed beds in nurseries. It will be appreciated that if seeds are planted as doubles or triples the two seedlings from such a planting will tend to kill off one another. If the seedlings are too close together then they also tend to choke off one another and if they are too far apart then the economy of the nursery is adversely affected as more space than is essential would be used.

It is an object of this invention to go some way towards overcoming the aforementioned disadvantages and to achieve the aforementioned desiderata.

Accordingly the invention may be said broadly to consist in a precision seeder comprising: a source of vacuum, vacuum pick-up means comprising a rotatable circular disc having a single ring of orifices passing axially therethrough, each said orifice being radially equidistant from the centre of the said disc, each said orifice being adapted to receive and retain a a single seed at one side thereof when said vacuum ■I 91 458 source is applied to the other side thereof, a source of seeds communicating with said ring of orifices on said disc on the face of said disc opposite said source of vacuum, vacuum release means co-operable in use with each said orifice to release said vacuum at a predetermined release point to thereby sequentially disengage each said retained seed, seed depositing means co-operable in use with said vacuum release means to transfer sequentially each said disengaged seed from said release point to a seed bed at a predetermined spacing from its next adjacent seed,said depositing means comprising fins projecting axially from a face of the disc so as to define with the inner circumferential face and flat face of a casing, a cell open radially inwardly, the vacuum release means being disposed so as to disengage seeds into said cell opening, the discharge point for discharging seeds radially outwardly of the said cells being an opening in the circumferential face of said^ chamber beginning slightly beyond bottom dead centre whereby each seed rests against a fin at the moment of discharge, means for synchronising the rate of discharge of said seed depositing means with the forward speed of motion of said seeder over the ground, the arrangement being such that in use said disc is rotated past said source of vacuum it picks up a seed on the pick-up end of said orifice and carries it to said depositing means where it is deposited in the soil. ' \ "3" \°l 11+^2 Alternatively said seed depositing means includes a first discharge point for discharging seeds radially outwardly of the said cells being an opening in the circumferential face of said casing, said seed depositing means further comprising an endless belt, said belt having fins projecting outwardly, said belt and fins positioned to travel in a guideway the guideway defining with said fins and endless belt a series of moving cells, said guideway having an intake opening in registry with said opening in the circumferential face of said casing and second discharge point slightly beyond bottom dead centre of a bottom pulley over which said endless belt rides whereby each seed rests against a fin at the moment of discharge.

The invention consists in the foregoing and also envisages constructions of which the following gives examples.

The invention may be more fully understood by having reference to the accompanying drawings wherein: Figure 1 is a sectional elevational view of a seeder mounted on a carriage being towed behind a farm tractor..

Figure 2 is a side elevational view of a seeder casing with the disc in place and with surface portion broken away so as to illustrate the operation of the seeder. 191458 Figure 2a is a fragmentary sectional view of a fin on the disc.

Figure 3 is a portion of the seeder casing which is attached to that portion illustrated in Figure 2.

Figure 4 is a side elevational view with parts broken away of a seeder according to a second embodiment of the invention.

Figure 5 is a top plan view with portions broken away of the seeder according to the second embodiment of the invention illustrated in figure 4.

Referring to figure 1 a seeder 10 is mounted on a carriage behind a tractor. Above seeder 10 is a hopper 11 carrying a supply of seeds. Preceding the seeder 10 is a / depth control wheel 12 which is adjustable in height through lower pivot arm 50 which is pivoted by turning handle 52. The seeder 10 is mounted intermediate a pair of ground wheels 14. Wheel 14 rotates on an inwardly projecting stub shaft 16. Shaft 16 is mounted within a casing 17 and has a sprocket which drives a driving chain 18 extending forwardly to a sprocket on main shaft 20. The sprocket driven by chain 18 is outboard of a differential into which two sections of main shaft 20 project. The purpose of this differential will be described later. Immediately above shaft 20 is a gear shaft 21 on which is mounted a sprocket over which chain 22 is engaged. Shaft 21 leads outboard to a sprocket in an outboard housing 23. Within that housing are an upper and a lower sprocket, the lower sprocket being mounted on a drive shaft 29. The outboard sprockets on shafts 21 and 29 191458 are interchangeable so as to be able to change the drive ratio of the seeder. A casing 25 is provided over the chain drive 24 between shafts 21 and 29. A further final chain drive 26 is provided within casing 27 to drive the main shaft 31 of the seeder. An additional mounting point for the seeder 10 is upper pivot arm 4 8 which is pivotally mounted to an upper frame member 42. The other end of frame member 42 is pivoted in link 4 6 which itself is mounted on a cross member 44 which provides rigidity between the two end plates 28, one of which is illustrated in figure 1. A double lifting catch 40 is pivoted on frame member 42. This member 40 hooks over lifting cross member 36 which is mounted^in a pivotal arm 32. Member 32 is pivoted at one end on plate 28 between stop members 34. An additional cross frame member 35 is provided for rigidity. Member 35 also forms a stop for pivot arm 32 , which when lifted'by the hydraulic arms of the tractor through chain 38, first lift the seeder units clear of the ground, and if the lift is continued, will lift the entire mechanism including the drive wheels as may be required for turning within small confines.

At the forward end of the frame a main frame cross member 30 is provided. An upper arm 54 and a lower arm 56 project forwardly. A screw crank 60 is provided to adjust the angle of pivot of lower arm 56 to the main tow bar 58 so as to level the apparatus as indicated by spirit level 13 mounted on the side of the hopper 11. The main tow bar is attached to a tractor through the attachment pin 62. The \21458 drive wheel 64 of the tractor is illustrated. A vacuum hose 15 is connected to the air intake of the tractor to provide the vacuum. The attachment is provided with a spring loaded valve set to provide sufficient vacuum for the seeders without impairing engine performance of the tractor. A large capacity air filter is also provided along the vacuum hose line 15 between the seeders and the engine intake to screen out foreign material.

The operation of the framework illustrated in figure 1 will now be described. The frame is mounted behind a tractor and positioned so that the seeder 10 is at the seed bed level A. The main land wheel 14 is positioned in the alley way at level B between the seed beds. Link chain 38 from the hydraulic lifting mechanism of the tractor has been lowered and hook 40 positioned in the correct position to allow this operation. As the tractor moves forward main land wheel 14 riding on land level B is rotated rotating shaft 16 and transmitting drive via chain 18 to shaft 20. The shaft 20 extends into a differential gearing, not illustrated. The reason for the differential is that although the seed beds are normally not curved there are occasions which one or other of the seed wheels might begin to skid or rotate at a slightly different rate from the other. It is highly desirable that the rotation speed of the seeder is constant relative to the speed of travel of the seeder over the ground and the provision of a differential in the drive linkage between the land wheels and the seeder assists in An additional factor is the provision of high traction \ s, such as for example all-terrain motorcyble tyres. 1S14-58 Drive from the differential attached to shaft 20 is transmitted by chain 22 to a sprocket driving a shaft 21 which extends outboard to the gearing housing 25. Gear ratios can be selected to speed up the rate of rotation of the seeder when desired for planting seeds closer together or alternatively to slow it down when seeds are to be planted' further apart. Drive is finally transmitted to seeder shaft 31 through drive chains 24 and 26 which are described above. . The depth at which the seeder operates is controlled by depth wheel 12 which can be adjusted by turning handle 52.

In an alternative embodiment, not illustrated, a combined differential and gear box unit could be substituted for the separate differential and gear box units just described.

In the embodiment illustrated there is a single seeder provided. However it will be appreciated that in operation one would have a number of seeders corresponding to the width of the seed bed to provide rows of seed therealong.

When multiple seeders are employed each seeder can be synchronised to discharge seeds at the same time so that seeds are deposited in rows normal to the direction of travel of the seeder. Each seeder will have a backing device on sprocket 31, which on slackening off when all seeders are in the fully raised position :(arms 32 -against cross member 35 and hook 40 engaged on cross member 36 by the lower of the two hooks (40)) will allow a mark on each individual disc to be matched with a mark on casting 66. When "timed" in this manner all discs will rotate in unison simultaneously dropping their seed in each drill, thus sowing the bed on a square pattern. — —— NX PATEV 25JANt 8 191458 In figure 2 the body 66 of the seeder is substantially flat and made of cast aluminium. There is defined in the body a cylindrical chamber 68 whose axis is relatively short in comparison with its diameter. A series of orifices 78 which interconnect pass to vacuum connection mouth 76. It will be seen that the annular line of these vacuum orifices extends anticlockwise from approximately 4 o'clock to approximately 7 o'clock in the circle. There is provided an annular wear surface 80 vhich is divided on either side of vacuum orifices 78 but which otherwise is continuous.

There is provided a recess 84 in wear surface 80, the purpose of which will be described later. In addition there is an air inlet hole 82 which is in registry with orifices 94 in disc 70 and will be described later. A coulter 104 is bolted into the front of the body 66 and plough members 106 are provided. It will be seen that a discharge lip 108 within the cylindrical chamber 68 is at a point slightly beyond bottom dead centre of the line.

Disc 70 fits snuggly within chamber 68. It is fastened onto shaft 31 by means of key 88 to rotate in a counterclockwise direction (figure 2), with shaft 31. At the outer periphery of disc 70 there are provided a series of fins 90 which are rivetted with rivets 92 to discj 70 as is illustrated in figure 2A. Symmetrically displaced around the disc inboard of fins 90 are orifices 94. When the disc is in position the orifices 94 are in register with vacuum orifice 78 and with air hole 82 in the body 66. A portion 72 of the casing 109 which fits onto body 66 is also illustrated. A 9 JAN 1984 19108 raker blade 100 and a doctor blade 102 are mounted radially outwardly and inwardly from the path of orifices 94. A sloping side 73 and surf ace--72, as are better illustrated in relation to figure 3 define with disc 70 a seed receiving area from hopper feeder inlet 74 (figure 3). Optionally nylon bristles 96 alternate with orifices 94 to agitate seeds 98 from the hopper to assist in singling of seeds.

Figure 3 illustrates the casing 109 which fits against the body 66 to enclose the seeder chamber 68. Coulter 104 and plough 106 from body portion 66 are also illustrated. Raker teeth 100 are adjustable by means of a screw 103. Similarly doctor blade 102 is adjustable by releasing a bolt 105 in a slot in the centre of blade 102. In the face of casing 109 there is a raised surface 110 and a recessed portion 113. The inlet 74 from hopper 11 is also illustrated Air inlet 112 is provided so that there is a greater pressure differential between the atmosphere side of disc 70 and the vacuum side thereof to thus better retain the seeds 98 in orifices 94. Inlet 112 is fitted with a vertical tube so that air drawn into the seeder originates from a clean air zone well above the bed surface, and may be fitted (if necessary) with a lightweight air filter to eliminate possibili of drawing in dust. Inspection windows 114 and 115 are provided so that an operator may check on the positioning of the singling aids and also cri the dropping of the seeds. - * Wear plate 116 which may be of TEFLON* or other suitable material is provided at the point where seeds drop from orifices 94 into N.Z. PATENT OFFICE ■ i —L JAN 191458 their respective cells. Wear plate 116 is positioned so as to press the disc against the annular wear surface 80 about the recess 84 to more effectively cut off the vacuum securing the seed 98 to orifice 78.

The operation of the seeder itself will now be described in relation to figures 2 and 3. A vacuum source such as the - / air inlet of a tractor is connected via flexible hose 15 (figure 1) to vacuum manifold 76. There is thereby provided a vacuum in vacuum orifices 78 in chamber 68. As the land wheels 14 are pulled forward the shaft 31 rotates in a counter-clockwise direction. The gate of hopper 11 is opened to allow passage of seeds 98 down the feed inlet 74. As agitators pass through the collection of seeds, usually single seeds 98, are received and retained in orifices 94 through the pressure differential which is provided by having a vacuum on one side and an air inlet on the other. Seeds 98 may be of regular or irregular shape. In the case of pinus radiata the seeds occassionaily are long and pointed as a result, as illustrated by seeds 99 a "double" will sometimes be retained in hole 94. As this hole passes teeth 100 and doctor plate 102 they are dislodged and a single seed continues in the revolution of th.e disc from that point.

After seeds have passed the end of vacuum inlet 7 8 at about 7 o'clock and their associated vacuum holes 94 are in register with recess 84 in the wear plate 80 they drop into each of the cells which are defined by the disc 70, the fins 90, the circumferential surface of casing 109 and the outer S'- ll 191458 casing 109. It will be seen that there is a single seed to each cell. By positioning the drop off lip 108 at slightly above or past bottom dead centre each seed is allowed to slide back in its cell against fin 90. This ensures that the spacing between each seed is the same. The height of lip 108 is minimised,. however, so as to reduce the incidence of bounce of the seed as it falls into the drill.

As the disc 70 continues its revolution each hole 94 becomes momentarily into register with air hole 82. This air stream passing through each orifice 94 allows the clearance of the dust or other foreign particles which might have become lodged in the hole. The usual foreign matter concerned is coatings for the seeds.

Under ideal conditions where dust is not present or is minimal air hole 82 could be dispensed with. However, under more normal conditions it is preferred to have some means of clearing orifices 94. An alternative would be an annular slot encompassing three or four orifices 94. Such a construction would preferably be accompanied by a wear plate similar to plate 116.

The seeder was tested in a seed bed using pinus radiata. The results of a portion of this test are set out in Table I. It will be seen that the singling of the seeds is achieved in over 90% of sowings and that the variation of the average spacing is minimal.

TABLE I ARASAN-42S COATED PINUS RADIATA SESD ESCAPEMENT (CENTRE TO CENTRE) ALONG DRILL (Cm) SEED SINGLING DISC REVOLUTIONS (48 Seed Holes) Distance Covered (Cm)* Average inter-seed space Total Distance Cm Average Seed Space Cm SEED SINGLING PERCENTAGES Quarter Revs. (12 Seeds) Quarter Revs. (12 Seeds) Single Seed Doublej Seed Blank Site Total % 1st 2nd 3rd 4 th 1st 2nd' 3rd 4th FIRST 68.4 67.0 67.4 67.6 .70 .58 .62 .63 270.4 .633 87.50% 6.25% 6.25% 100% SECOND .67.1 66.7 66.5 67.2 .59 .56 .54 .60 267.5 .573 95.83% 2.08% 2.08% 100% THIRD 66.5 67.7, 67.9 66.9 .54 .64 .66 .57 269.0 .604 85.50% ''.2.10% .40% 100% FOURTH 64.5 67.7( 66.6 67.2 • .37 .64 .55 .60 266.0 .542 91.66% 4.17% 4.17% 100%"- FIFTH 66.8 66.4 68.0 66.8 .57 .53 .67 .57 268.0 .583 89.60% 8.30% 2.10% 100% AVERAGE 66.7 67.1 67.3 67.1 .56 .59 t .61 .59 268.2 .587 90.40% i 4.60% .00% 100% *Note; Governed by distance covered by master landwheel running along alleyway between beds, and not directly to the bed surface.

N V> . 19I45S A second embodiment of the invention is illustrated in Figures 4 and 5. This embodiment may be employed with apparatus where the vertical distance to be travelled by the seeds is greater than that for the embodiment of figures 1 to 3.

The seeder unit 120 comprises a hopper 122 which feeds into a sub hopper 12 6 as in the previous embodiment. The . main component of the first portion of this embodiment of the seeder is the singling disc 130 mounted on shaft 128. in one preferred embodiment this disc 130 has a construction which is the same as that of disc 70 illustrated in figures 1 to 3. A series of fins 131 project axially out of the face of the disc. Vacuum orifices 129 align with an annular slot. Nylon agitator bristles 133 may be provided but are optional. It has been found that by providing a strong vacuum along vacuum hose 124, the bristles 133 need not be employed. Also by use of a stronger vacuum, vacuum holes 129 may be reduced in diameter from vacuum holes 94 of disc 70 of the embodiment of figures 1 to 3. Disc 130 is mounted on a driven shaft 128 as before.

The major change in the seeder is the provision of an endless belt 134 which has a series of fins 135 projecting upwardly therefrom. This belt rides in a casing or guideway 137 and there is defined between the belt, the fins and the casing a series of moving cells, each of which carries a seed. These cells are sychronised to align with orifices 129 of disc 130. The alignment may be assisted by the use of fins 131 but these are optional. Release of seeds from ■J*2 .■ , 1914-53 disc 130 is achieved in the same fashion as with the release of seeds from disc 70.

Endless belt 134 passes over driven sprocket 132 and idler sprocket 152. Driven sprocket 132 is mounted on the shaft 166 through a flange from a main cross frame chanel member 136. Sprocket wheel 132 may be driven by a driven shaft 13 8 which drives a chain 139. Alternatively, sprocket wheel 132 may drive disc 130 suitably provided with teeth around its circumference.

The frame on which the seeder is mounted is similar to that 10 shown in figure 1. Main side frame panel 140 has a slot 143 therethrough. A bar 142 is provided in slot 143 for raising the apparatus as shown in ghost.

Idler sprocket 152 is mounted on a tensioning bar 144 which can be moved away from sprocket wheel 132. In an alternative embodiment an endless chain such as from a chain saw can be employed and a saw bar substituted for idler sprocket 152 and tension bar 144.

Plough 146 is a chisel coulter to dig the furrow into which seeds are to be planted. It will be seen that the inner portion 20 of casing 137 behind plough 146 passes beyond the bottom dead centre position and raises upwardly slightly into a lip 147 which provides for even depositing of seeds 148 as will be explained below. Depth wheel 150 is provided to control the depth planting of the seeds.

Turning to figure 5 main power shaft 156 is mounted in bearing 154 on frame side panel 140. ■ On'frame member 136 there is mounted a pair of mountings 159 the positions of which are controlled by locking wheel 158 the manner to be explained below. An auxiliary mounting 160 is provided for 19 1458 a seeder unit. Auxiliary drive wheel 162 provides drive for the seeder unit. Wheel 162 is driven along shaft 163 by electric motor 164.

A further drive shaft 166 is provided with a series of cog wheels 168. These cog wheels mate with a cog wheel 170 on main power shaft 156 to drive shaft 166. In operation this embodiment of the invention operates very similarly to that of the first embodiment. The seeder 120 is mounted on a carriage towed behind a prime mover such as a tractor.

Seeds 148 in hopper 122 are fed into sub-hopper 126 in the same manner as the sub hopper 74 is fed in embodiment of figures 1 to 3. Disc 130 rotates in a clockwise direction in the embodiment shown in figure 4. Seeds 148 are picked up singly in orifices 129 and rotated to positions just above the point where the edge of disc 130 mates with orifice 141 through casing 137. The seed releasing means of disc 130 which is the same as that of the other embodiment of the invention releases single seeds through orifice 141 into a single cell formed by a pair of fins 135, the casing 137 and the belt 134. Fins 131 are of assistance in aligning seeds with a cell on the belt but it will be seen that they are not essential to the operation of disc 130.

In another mode of operation according to the invention disc 130 and conveyor belt 134 are sychronised so that a seed is dropped into every second cell. A second disc is positioned at some point in the travel of belt 134 so as to deposit a seed also into every second cell, the sychronisation being such that there is a seed in every cell. Such an 19.14-58 operation would be employed for doubling of the ground speed.

Sprocket 132 illustrated in figure 4 is travelling in a counter-clockwise direction as illustrated by the arrow.

Seeds 14 8 in the cells then proceed down the bottom run of the chain to a position behind plough 146 where the casing starts to travel upwardly again. Gravity forces the seeds back against fins 135 to ensure that the positioning of the seeds is uniform. Thus the fins 135 serve the same function as the depositing of seeds by fins 90 over lip 108 on disc 70 in the earlier illustrated embodiment.

The mounting 160 is provided so that the upper seeder unit portion can be removed for servicing or for making adjustments. -Auxiliary drive wheel 162 will rotate the seeder unit in, the disengaged position independently of any forward movement of the implement or prime mover. This allows an operator to make adjustments to the seeder, the choke plate controlling the rate of transfer of seeds from hopper to sub hopper 126 and other adjustments. Hopper 122' is illustrated in this position in figure 5. 1914 58 The vacuum pickup orifice diameters on the discs were measured under the vacuum from a domestic vacuum cleaner and also under a vacuum of -1.7 5 KPa. The diameters found to be useful are set out in Table II herein below. These diameters are expressed in millimetres.

TABLE II Vacuum Pickup Orifice Diameters (mm) Seed Vacuum Cleaner Maize 1 4.0 Sunflower 2.8 Pinus Radiata 1.8 -1.75 KPa 2.8 1.6 1.0

Claims (16)

WHAT WE CLAIM IS: 191458

1. A precision seeder comprising: a source of vacuum, vacuum pick-up means comprising a rotatable circular disc having a single ring of orifices passing axially therethrough, each said orifice being radially equidistant from the centre of the said disc, each said orifice being adapted to receive and retain a single seed at one side thereof when said vacuum source is applied to the other side thereof, a source of seeds communicating with said ring of orifices on said disc on the face of said disc opposite said source of vacuum, vacuum release means co-operable in use with each said orifice to release said vacuum at a predetermined release point to thereby sequentially disengage each said retained seed, seed depositing means co-operable in use with said vacuum release means to transfer sequentially each said disengaged seed from said release point to a seed bed at a predetermined spacing from its next adjacent seed, said depositing means comprising fins projecting axially from a face of the disc so as to define with an inner circumferential face and flat face of a casing, a cell open radially inwardly, the vacuum release means being disposed so as to disengage one seed only into each said cell opening, the dischage point for discharging seeds radially outwardly of the said cells being an opening in the circumferential face of said casing beginning slightly -19- 191 45 beyond bottom dead centre whereby each seed rests against a fin at the moment of discharge, means for synchronising the rate of discharge of said seed depositing means with the forward speed of motion of said seeder over the ground, the arrangement being as such that in use/said disc is rotated past said source of vacuum it picks up a seed on the pick-up end of said orifice and carries it to said depositing means where it is deposited in the soil.

2. A precision seeder according to claim 1 wherein said vacuum source communicates with an annular slot which in use is in registry with said orifices through said disc.

3. A precision seeder according to claim 1 or 2 wherein there is also provided a singling aid co-operable with said orifices in said disc to agitate seeds associated with said orifices to assist release of extra seeds therefrom.

4. A precision seeder according to claim 3 wherein said singling aid comprises raker teeth positioned radially outwardly from said disc orifices and a blade positioned radially inwardly therefrom.

5. A precision seeder according to any one of claims 2 to 4 wherein said annular slot is provided in a casing defining a cylindrical chamber, said slot being on one end face of said casing, the arrangement being such that in use the vacuum draws the disc against said one end face.

6. A precision seeder according to claim 5 wherein said annular slot extends less than 360° around said one end face and said vacuum release means comprises a recess in said one end face allowing the entry of air on the vacuum side - 20 - '.i-i* ^ » 191458 of said disc.

7. A precision seeder according to anv one of the preceding claims wherein said fins are arcuate in section in radial view.

8. A precision seeder as claimed in any one of the preceding claims wherein said seed depositing means further comprises an endless belt, said belt having fins projecting outwardly, said belt and fins positioned to travel in a guideway the guideway defining with said fins and endless belt a series of moving jsells, said guideway having an intake opening in registry with said opening in the circumferential face of said casing and a discharge opening slightly beyond bottom dead centre of a bottom pulley over which said endless belt rises whereby each seed rests against a fin at the moment of discharge

9. A precision seeder according to any one of the preceding claims wherein there are provided a coulter and side ploughs in association with said •coodli.'hg- device to provide a furrow into which seeds are planted.

10. A precision seeder according to any one of the preceding claims wherein said seeder and associated coulter are preceded by a depth wheel.

11. A precision seeder according to any one of the preceding claims wherein said seeder is irounted on a framework intermediate a pair of around wheels. ** •" r - \ i ' />* - 21 - ■. -3E-L,

12. A precision seeder according to claim 11 wherein the framework is adjustable so as to be at a constant orientation with respect to the ground.

13. A precision seeder according to claim 11 or 12 wherein there is provided differential drive means intermediate the ground wheels and the seeder to ensure that a constant rate of drive is supplied to the seeder.

14. A precision seeder according to any one of the preceding claims wherein said vacuum source is the air intake of a. tractor pulling said seeder.

15. A precision seeder substantially as herein described with reference to Figures 1 to 3.

16. A precision seeder substantially as herein described with reference to Figures 4 and 5. ByWfc/Thsir Authorised Agents, A. J. PAR.'C & SON