GB2053641A - Coffee harvester - Google Patents

Abstract

A coffee harvester comprises a frame (24, 26) with oscillatory tined, shakers (32, 34) arranged one on either side of a centre line (35). The shakers have a plurality of arrays of tines (56) which are caused to oscillate about a longitudinal axis of the shaker unit by an oscillation generator (36). The oscillations have a maximum acceleration of at least 50g and the rate of acceleration from the zero velocity point of each cycle is greater than that of the corresponding since wave. The harvester includes two conveyors one below each shaker unit, and each conveyor has an upper, crop collecting run which is synchronized to move at exactly the opposite speed to the speed of advance of the harvester so that the catching trays are stationary with respect to the plants. The acceleration characteristic of the shakers is achieved by the generator 36 including eccentric weights which are selected so that they generate oscillations in the tines or shakers with a motion as close as possible to that of a saw-tooth wave instead of a sine wave. <IMAGE>

Description

SPECIFICATION Coffee harvester This invention relates to coffee harvesters.

Over a period of at least twenty years attempts have been made to mechanize the harvesting of coffee beans. Hand picking has always been a laborious operation and even in comparatively under developed countries the provision of manual labour to gather the harvest has become increasingly difficult and has been a contributory factor in the increased cost of coffee on a world-wide basis.

It is essential for machine harvesting to be successful and gain widespread acceptance that the machine should detach from the plants a high percentage of the beans, that the damage to the plants should be small and should not permanently affect the plant and that the machine should be adaptable for different varieties of plant. It is furthermore, desirable that the harvester should be capable of turning in confined spaces, capable of harvesting crops from frost damaged trees without the resultant dead twigs affecting operation of the machine and overall should be simple to service and repair under field conditions.

Previously proposed machines have failed to meet at least some of these requirements and probably the main inadequacy of such machines has been their inability to detach a sufficiently high proportion ofthe beans from the branches. Even comparatively experienced workers are not always successful in detaching beans from the branches when harvesting manually.

Although it is not essential to do so, it is desirable that the harvester should collect the detached beans and deliver them with a minimum of leaves, twigs and other trash to suitable containers such as sacks.

According to the present invention there is provided a coffee harvester comprising at least one rotary, oscillatory shaker incorporaing a plurality of arrays of tines which each tine extending generally radially from an axis about which the oscillations are generated and means for imparting to the tines an oscillatory motion with a rate of acceleration in each cycle from the zero velocity position in excess ofthe rate of acceleration of a corresponding sine wave.

Further according to the present invention there is provided a coffee harvester comprising at least one shaker unit, each unit having a plurality of arrays of tines spaced along an axis, means for generating oscillations in the arrays of tines about said axis, each oscillation cycle having a velocity characteristic such that the acceleration from the zero velocity point of the cycle is appreciably greater than the acceleration in a corresponding sine wave.

Still further according to the present invention there is provided a coffee harvester comprising at least one rotary, tined, shaker unit, drive means for oscillating the tines of the shaker unit with an oscillatory motion having a characteristic such that the acceleration from the point of zero velocity is greater than that of a sine wave, and the tines being arranged as a plurality of arrays along the axis of the oscillations, the tines of the various arrays being inclined at at least two different angles relative to the axis of the oscillations.

Yes further according to the present invention there is provided the combination of an agricultural tractor and at least one shaker unit including a plurality of arrays of tines spaced along an axis, means for oscillating the arrays about said axis with an oscillatory cycle in which the acceleration from the point of zero velocity is freaterthan that of a sine wave.

Yet further according to the present invention there is provided a coffee harvester comprising at least one rotary, tined shaker unit, drive means for oscillating the tines of the or each unit with an oscillation aboutthe longitudinal axis ofthe unit with a characteristic giving from the point of zero velocity an acceleration greater than that of a sine wave and means mounting the unit or units on the framework of the harvester for movement towards and away from the longitudinal centre line of the harvester.

An embodiment of a coffee harvester in accordance with the invention will now be described, by way of example with reference to the accompanying diagrammatic drawings, in which: Figure 1 is an outline side elevation ofthe harves terwith side panels omitted; Figure 2 is a plan view of the harvester; Figure 3 is a rear elevation of the harvester; Figure 4 is a plan view of one shaker unit ofthe harvester but with an oscillatory drive omitted and only two rows or arrays shown, the lower array being shown in chain lines; Figure 5 is a side elevation ofthe shaker unit of Figure 4; Figure 6 is a side elevation, to an enlarged scale, of a two-part mounting collar for one array of tines; Figure 7 is a plan view of the collar of Figure 6;; Figure 8 is a longitudinal section of a hydraulic support cylinder for one front wheel of the harvester with steering means incorporated therein; Figure 9 is a plan view on the line A-A of Figures; Figure 10 is a section, to an enlarged scale, on the line 10-10 of FigureS; Figure 11 is a side elevation, to an enlarged scale, showing the mounting arrangement of one rear wheel, the wheel itself being omitted; Figure 12 is a plan view of one collecting conveyor of the harvester; Figure 13 is a plan view, to an enlarged scale, illustrating a rearward end portion of the conveyor of Figure 12; Figure 14 is a fragmentary view, with parts omitted, of a fan arrangement forming part of the end portion of Figure 13; Figure 15 is a side elevation of a bucket elevator of the harvester;; Figure 16 shows one bucket of the elevator of Figure 15; Figure 17 is an end view of a harvester with most parts omitted showing a modification in which the The drawings originally filed were informal and the print here reproduced is taken from a laterfiledformal copy.

shaker units are movable towards and away from the longitudinal axis ofthe harvester; Figure 18 is a perspective view of an agricultural tractor with a shaker unit as illustrated, for example, in Figures 4 to 7; Figure 19 is a longitudinal section of a shaker unit head which oscillates the tines; and Figure 20 is a perspective diagram showing the circuit of a synchronizing gearforthe conveyor of Figure 12.

The coffee harvester in accordance with the invention will now be described in general outline with reference to Figures 1 to 3 of the drawings. The working parts are mounted on a frame including an upper or deck portion 20, a lower portion 22 and various uprights 24 interconnecting portions 20 and 22. Ladders 26 are provided (only one shown) to provide access to the deck portion 20. The machine is supported on two, front, steerable wheels 28 and two rear wheels 30. An engine 32 which provides power for hydraulic motors of the machine is mounted at the rear of the deck portion 20.

Two rotary and oscillatory shaker units 32, 34 are mounted symmetrically with respect to the longitudinal centre-line 35 of the machine. Rotary motion is provided by the interaction of tines of the units 32,34 with the coffee plants as the machine progresses along a row and oscillatory motion of the shaft carrying the tines is provided by an eccentric weight arrangement 36 mounted at the upper end of each unit.

Coffee beans dislodged from the plants are collected by conveyors 38,40, one extending along each side of the longitudinal centre line of the machine. These conveyors are fully described in our cognate co-pending British patent applications 28098/76 and 36436/76.

At the rear ofthe machine bucket elevators 42,44 (one for each conveyor) are provided which serve to lift beans collected by the conveyors to a chute 46 which discharges above a platform 48 carrying a sack or other container (see also Fig. 15).

The individual parts of the machine will now be described with reference to the remaining Figures of the drawings.

Each shaker unit 32, 34 is of robust construction since it must withstand oscillatory motion about it longitudinal axis and hence a main shaft 50 of each unit is made of 5 mm thick steel pipe supported at the lower end by a thrust bearing 52 mounted on a longitudinal member 53 of the frame and at the upper end by a journal bearing 54 mounted on a transverse member 55 of the deck portion 20. In the preferred construction the shaft has an outer diameter of 16.5 cm. The precise dimensions are not, of course, critical, but they must be adequate to withstand the fatigue stresses generated by the oscillatory motion. The oscillatory generator will be further described with reference to Figure 20.

The shaft 50 carries a total, in the preferred embodiment, of twenty-one collars each split into two halves 57 and each half having at each end face upper and lower lugs 59 by which the two halves can be secured together by bolts. Thus the two havles are secured together with four bolts to ensure a reliable and firm clamping action. The lugs also act as vertical spacers and if a relatively large spacing is required between adjacent collars the collars are mounted in abutting relationship If a closer spacing is required the lugs of adjacent collars are nonaligned.

Each half collar 57 has fifteen blind holes 61 into each of which a tine 56 is introduced. The upper ten arrays of tines all extend radially outwardly from the respective collar, that is all tines of any one collar lie in the same plane. The lower set of arrays of tines (eleven arrays} are spaced from the upper set of rows by an amount slightly greater than the distance between individual rows of any one set. In addition the uppermost eight arrays have tines which are angled upwardly at an angle of about 8" while remaining in a radial plane including the longitudinal axis. The lowermost three arrays of the lower set have a smaller spacing between the rows by arranging the lugs in non-abutting relationship.The tines of the top one of the arrays of these three arrays extend radially outwardly, or in other words collectively lie in a plane whereas the tines of the lowermost two arrays are inclined downwardly at an angle of approximately 8 to the horizontal while each lies in a radial plane including the longitudinal axis ofthe shaker.

Each tine 56, in the preferred embodiment is 57.5 cm long and is secured in the corresponding blind bore 61 of its collar 57 with an epoxy resin. The tip portions 63 are frusto-conical to assist penetration between branches of a plant. The tines are of glass fibre.

Although a specific arrangement has been shown and described, it will be apparent that other tine array configurations can be used. The one shown has been successful in harvesting mature crops as well as relatively green crops and is capable of stripping at least about 95% of the crop without appreciable damage to the plants themselves. The angular orientation of the tine arrays will depend upon the growth pattern ofthe plants to be harvested, and in particular the tines at any given level will not be parallel to plant branches at that level.

The drive arrangement 36 includes eccentric weights which are selected so that they generate oscillations in the tines with a motion as close as possible to that of a saw-tooth wave instead of a sine wave which has been found to have too large a period in its cycle when the acceleration is inadequate just afterthan point in the oscillatory cycle when the tines are at rest. Normally a sine wave provides comparatively slow acceleration from the point of zero velocity and hence the forces acting on the twigs or branches are smaller than necessary effectively to shake the fruit from the plants. This higher acceleration rate is achieved by the particular con figuration of the eccentric head and by the mass selected from the weights as described hereinafter with reference to Figure 20.

To achieve satisfactory removal of coffee beans from the plants both when fully mature and when relatively green it is necessary that the maximum acceleration of the tines should be at least 509 and in the preferred embodiment this figure is 549. It is also important that the tines should have the correct degree of rigidity and a diameter of about 2-0 cm when made of glass fibre has been found adequate.

The tines shou Id be sufficiently rigid to prevent flexing along the length which absorbs energy and reduces the efficiency of detachment. However, over rigid tines are more liable to damage the plants. The amplitude of oscillation is 4.5 cm in the preferred embodiment and the frequency 1000 c.p.s. The amp- litude may be greater in some harvesting conditions and the frequency can be varied over a range from 800 to 1300 c.p.s.

The overall diameter of each shaker unit should be large, say ofthe order of 1.20 m to 1.8 m; in the preferred embodiment the diameter is approximately 1.5 m. The reason for the choice of diameter is that if the diameter is too small the tines remain in the plants for too short a period. Diameters in excess of 1.8 m result in an unwieldy harvester with no compensating benefit.

The oscillation generator to be described with reference to Figure 20 provides the desired operational parameters and the nature of the construction is such that if a tough branch is encountered the amplitude of oscillation is automatically reduced while the frequency and maximum acceleration are not unduly adversely affected.

The space available in coffee plantations for turning a large harvester is often limited and hence it is necessary to provide steering gear while will accommodate such limitations. At the same time plantations sometimes involve transverse slopes and hence it is necessary to adjust the attitude of the harvester frame to the ground wheels. These requirements are to some extent incompatible since, generally, steering gear cannot conveniently accommodate large vertical movements without adversely affecting its action.

To overcome this problem an hydraulic cylinder 60 is mounted to support each front wheel 28 and a steering shaft 62 passes through an upper end cover and bearing assembly 64. A downwardly-extending extension 66 of the shaft 62 is of hexagonal section and slidably engages in a complementary aperture 63 in the upper end portion 68 of the piston rod 70 of the hydraulic cylinder. The corners 71 of the aperture 63 are cut away to avoid binding of the extension 66.

The assembly 64 includes a hollow cylindrical bearing housing 72 welded at 74 to the upper end of the cylinder 60 and having an upper end cover76 secured by a row of bolts 78 screwed in tapped bores of the hollow cylinder 72. Seals 80 act between a bore of the cover 76 and the shaft 62. A thrust roller bearing 82 is mounted in the lower end portion of the cylinder 72 and the inner race thereof is secured in position by a nut 84 and lock nut 86. The inner face of the end cover 76 has a downwardly-facing annular recess 88. The broken lines a in the shaft 62 indicate that its full extent is substantially greater than shown. Likewise broken lines!;, c and d indicate respectively that the hexagonal extension 66, the cylinder 60 and the piston rod 70 are longer than shown.

The hydraulic cylinder 60 has a connection 90 for hydraulic pressure fluid and the lower end of the cylinder carries on a lower flange 92 thereof a lower seal assembly 94 accommodating seals 96 operative between the piston rod 70 and the inside surface of the cylinder.

The upper end portion of the rod 70 has secured to it by set bolts 98, an annular member 100 which defines the hexagonal passage complementary to the extension 66. This annular member 100 has preipheral seals 102 co-operating with the inside surface of the cylinder 60. The lower extremity of the extension 66 has a transverse bore 104 which receives a pin 106 which acts to prevent excess movement of the shaft 62 with respect to the piston rod. The pin 106 in the extreme position illustrated abuts the underside of a ring 108 welded concentrically to the upper end of the piston rod 70. The pin is fitted through apertures 110 in the piston rod which are subsequently blanked off by plugs 112. The lowermost end of the piston rod 70 has welded to it a core 114 and a heavy transverse plate 116 which in turn carries support structure (not shown) of one front wheel.A drain plug 114 adjacent the lower end of the cylinder serves to drain any fluid which has passed the seals.

The rear wheel assembly illustrated in Figure 11 incorporates an hydraulic motor 120 mounted in the hub and a disc brake 122 is operative with an hydraulically operated caliper 124. The wheel (omitted to allow other parts to be shown) is mounted on one of the uprights 24 ofthe frame through a pivotal beam 126, the location of which is controlled by a doubleacting hydraulic pressure cylinder 128. The cylinder 128 is secured by a clevis 130 to the upright and at the other end by a clevis 132 to the beam 126 adjacent the wheel hub 120. The angular location ofthe beam 128 is under the control of the operator of the vehicle as is the control of the forward hydraulic cylinders 60. Both the forward cylinders and the rearward cylinders are designed to provide some resilient movement as well as to correct the orientation of the harvester according to transverse and fore-and-aft ground slopes.The hydraulic circuits which control the operation of the cylinders are conventional and will not be described. The hydraulic fluid is held in reservoirs 33 (Fig. 3).

Referring now to Figure 12, it will normally be a requirement of the farmer that detached coffee beans will be collected rather than allowed to fall on the ground and to provide for this two longitudinally-extending conveyors 140 are provided, one below each shaker unit and one of the conveyors described in detail in our co-pending British Applications 28098/76 and 36436/76 is shown in Figure 12. A part ofthe other conveyor is shown in chain lines and an obstruction such as the centre of a plant is indicated at D.

The conveyor 140 comprises two drive chains (not shown) driven through sprocket wheels 142 (broken lines). The chains carry pairs of slide rods 144 which, in turn, carry rectangular shallow trays 146 which serve as the conveying carriers. On the lower run, the trays 146 lie centrally between the chains but on the upper run the trays are guided inwardly towards the centre line 35 of the harvester by cam tracks 148 which co-ope'rate with cam followers (not shown) on the trays in the form of sleeves lined with nylon bushes. Springs bias the trays towards the cam tracks, so that contact with an obstacle overcomes the spring force and the corresponding cam follower moves away from the cam track. The cam tracks must be rigid to avoid deflection by the resistance offered by the plants.

When harvesting coffee plants which are either old or have been the subject of frost damage, the shaker units are liable to break off brittle twigs as well a shake offthe beans and the trays collect these and transport them to the rear ends of the conveyors.

The subsequent delivery ofthe beans to sacks is hindered by the presence of twigs and other trash and to avoid problems in the bucket elevators a deflector blade 160 angled across the trays serves to deflect twigs and trash from the tops of the trays to the ground. A further deflector plate 162 has an edge portion 164 which acts in the same manner.

In order to remove leaves and other lighter trash a casing 166 is mounted at the zone where the conveyor discharges the beans to an auger 168 which in turn delivers to the lower end of the bucket elevator 42. The casing is connected through a short length of ducting to the inlet of a fan 170, the outlet of which discharges leaves and other trash through an outlet 172. The fan is driven by an hydraulic motor 174 and maintains a suction sufficient to remove trash but leave beans to fall into the auger.

The bucket elevator 42 illustrated in Figures 15 and 16 consists of a conveyor belt 179 with evenly spaced triangular section buckets 180 secured to the belt by nuts and bolts 182. The buckets discharge into the chute 46, the lower end portion of which houses a flap valve 184 manually controlled by a handle 186. The valve is used when a full sack is to be exchanged for an empty one. The elevator is driven by an hydraulic motor 188 at a top end sprocket 189. The bucket elevator also acts as a transmission belt to drive the auger 168. A device to grip a sack and hold it at the lower end of the chute 46 is provided at the lower end of the chute.

In order to reduce further the risk of damage to the plants, and to enhance the harvesting capability, the shaker units hereinbefore particularly described or modifications thereof may be mounted in guide tracks as illustrated in Figure 17. Each shaker unit is generally similarto that already described in detail with reference to Figures 5, 6 and 7 although the angular configuration of the tines 56 differs, by way of illustration of possible modifications, to suit coffee plants with a different growth pattern.

Guide tracks 116, 118 and 120, 122 serve to guide the shaker units towards and away from the centre line 35 of the harvester and this centre line will normally coincide with the centre line of the row of plants 126. The motion may be effected by one of more hydraulic actuators (not shown) operating on each shaker unit and such actuators may be controlled by appropriate sensors and a servo-system to cause the shakers to move around one half of the periphery of each plant.

It is also possible merelyto spring-load each shaker unit towards the plants 126 so that the shak ers move transversely automatically as the resistance offered by the plants varies.

In an alternative, unillustrated construction, each shaker unit is mounted for limited swinging move menttowards and away from the centre line 35. As for the illustrated construction motion may be controlled positively by hydraulic actuators or by springs or any other means which will control movement with respect to the longitudinal centre line 35.

Although in the preceding text reference has been made primarily to a harvesterwhich applies force to both sides of a coffee plant simultaneously, under some circumstances, for example when it is not desired to collect beans which have been detached from the plants, a shaker unit can be mounted on a conventional tractor as illustrated in Figure 18. This Figure shows a conventional agricultural tractor 220 (chain lines) carrying a frame 222 of box-section members, including two transverse members 224, 226, the lower one 226 of which is secured to the tractor by brackets 228 (only one shown) and the upper one 224 of which is supported by two uprights 230, 232, connected by plates 234 and bolts to the lower transverse member.Bracing struts 236 are provided between the uprights and the uppertransverse member 224, and between the junctions ofthe uprights and the upper transverse member on the one hand and the front end of the tractor 220 on the other hand.

As shown, the frame carries only one rotary shaker unit 240 or may carry two units arranged symmetrically on one side and the other of the tractor. In either construction, the or each rotary shaker unit is supported on laterally overhanging parts of the upper and Iowertransverse members.

Each shaker unit 32,34 has an oscillation generating means or head 36 which serves to oscillate the tines with an oscillation cycle which has an acceleration characteristic such that the acceleration from the point of zero velocity is greater than that of a corresponding sine curve. Further the head provides at a rotational velocity of 1000 r.p.m. a maximum acceleration of at least 50 g. In the preferred embodiment being described this maximum acceleration is approximately 54g.

An input shaft 402 ofthe head is driven by an hydraulic motor (not shown) and is supported by the upper bearing 54 mounted on the upper part 20 of the harvester frame and a lower bearing (preferably a thrust bearing) 52 mounted on the lower part 22.

As previously described, the tine arrays 56, 59 are mounted on a tabular shaft 50 and this is secured at its upper end to a spigot 404 bolted to a central bearing housing 406 of generally cylindrical form co-axial with the shaft 402 and the tube 50. The housing 406 has upperandlowerannularflanges408,4l0which serve to secure on upper rectangular plate 412 and a lower rectangular plate 414. A pair of ball bearings 411,413 is interposed between the shaft 402 and the bearing housing 406.

The rectangular plates 412,414 carry two stub shafts 416,418 rotatably supported in upper and lower bearings 420,422 carried in bearing housings 424,426. Each stub shaft 416,418 has has keyed to it between the plates 412,414 a weight 428,430 of T-shape in plan view. The weights are clamped by bolts 429,431 as well as being keyed to ensure that the weights are tightly held on the stub shafts. Four tubular spacers 432 are located between the plates 412,414 one at each corner thereof and a nut bolt and washer assembly 434 serves to clamp the spacers between the plates. The spacers are, of course, disposed so that they do not interfere with rotation of the weights.All the nuts used in the assembly are lock nuts because the acceleration forces are high with consequent risk of slackening.

The shaft 402 drives the stub shafts 416, 418 through toothed belts and pulleys 436, 438.

The weights 428, 430 are of T-shape so as to displace the centres of gravity as far as reasonably possible from the respective stub shaft thereby increasing the rate of acceleration during each oscillatory cycle beyond that of a sine wave.

The conveyor illustrated and described with referpence to Figure 12 can be synchronised to remain stationary with respect to the plants by a synch ronising system described and ciaimed in our co-pending application No. 7926971 dated 2nd September, 1976.

Alternatively, a system as illustrated in Figure 20 can be employed and this has the advantage of greater simplicity. An unloaded g round wheel 300 having lugs 302 adjacent its periphery drives through a sprocket and chain drive a hydrostatic metering valve 304 the output of which is directly proportional to ground speed. The metering valve receives pressure hydraulic fluid from a pump 306 and delivers the fluid to the hydraulic motors 308 which drive the conveyors. The circuit is provided by the lines indicated.

A suitable hydraulic metering valve is manufactured by TRW Ross Gear Dvision of 800 Heath Street, Lafayette, Indiana, U.S.A. 47902 and marketed under the designation HGA 20.

In operation, the harvester is positioned to straddle a row of coffee plants and then advanced along the row with the longitudinal centre line 35 of the harvester substantially coincident with the centre line of the row. The conveyors synchronising the wheel 300 is lowered to contact the ground and this controls motion of the conveyors so that the rearward speed ofthe upper, bean-collecting, run is exactly matched to the forward speed of the machine as a whole. The trays 146 of the conveyors meet or substantially meet on the centre line of the machine except where a part of a plant prevents this.

There is no longitudinal movement (i.e. in the direction of advance of the harvester) of the trays relative to the plants and hence no damage to conveyor or plant can occur while at the same time relatively few beans are lost owing to substantially complete ground coverage by the two conveyors.

Beans collected by the conveyors are passed through the cleaning arrangement including the deflectors for removing twigs and through the augers to the bucket elevators. The beans are delivered to the chutes and loaded into bags gripped at the lower ends of the chutes by the gripping means (not shown). The rate of advance of the harvester along a row is at least one kilomete per hour, but will normally be about 3 kilometers per hour. The loss of crop and green leaves is small, although frostdamaged or otherwise dead leaves are generally removed which is beneficial as these are liable to harbour grubs, insects and spiders. The accompanying photographs illustratefurtherthe harvester herein described.

Claims (27)

1. A coffee harvester comprising at least one rotary, oscillatory shaker incorporating a plurality of arrays of tines with each tine extending generally radially from an axis about which the oscillations are generated an means for imparting to the tines an oscillatory motion with a rate of acceleration in each cycle from the zero velocity position in excess of the rate of acceleration of a corresponding sine wave.

2. A coffee harvester comprising at least one shaker unit, each unit having a plurality of arrays of tines spaced along an axis, means for generating oscillations in the arrays of tines about said axis, each oscillation cycle having a velocity characteristic such that the acceleration from the zero velocity point of the cycle is appreciably greater than the acceleration in a corresponding sine wave.

3. A coffee harvester according to claim 1 or claim 2, wherein the tines extend radially from said axis.

4. A coffee harvester according to claim 1, claim 2 or claim 3, wherein at least some of the arrays of tines lie at an angle to the said axis while lying in a radial plane.

5. A coffee harvester according to claim 1 or claim 2, wherein the arrays of tines are divided into two sets, in one set the tines extending radially and in the other set the tines of at least some of the arrays being inclined to the radial direction but lying in respective radial planes in relation to the said axis.

6. A coffee harvester according to claim 5, wherein the said axis is substantially vertical and the sets of arrays are disposed one above the other, the tines of the upper set extending generally radially while the arrays of the lower set include tines which are inclined upwardly, horizontally, and downardly, the upwardly inclined tines being in upper arrays of the lower set.

7. A coffee harvester according to any one of the preceding claims, wherein the tines of any one array are offset when viewed along the said axis with respect to the tines of the next adjacent array, or arrays, so that overall the tips of the tines define a very shallow helix.

8. A coffee harvester according to any one of the preceding claims, wherein tip portions ofthetines are frusto-conical.

9. A coffee harvester according to any one of the preceding claims wherein the means for generating oscillations in the tines comprises two out-ofbalance weights driven in rotation at opposite sides of the said axis.

10. A coffee harvester according to claim 9, wherein the out-of-balance weights are rotatably mounted between two plates fast for movement with a shaft carrying the arrays of tines.

11. A coffee harvester according to any one of the preceding claims wherein the means for generating the oscillations is operative to generate at the tines a maximum acceleration in a cycle of at least 50g.

12. A coffee harvester according to any one of the preceding claims comprising two shaker units, one disposed opposite the other in relation to the longitudinal axis of the machine.

13. A coffee harvester according to claim 12, comprising means mounting the shaker units for movement towards and away from the longitudinal centre line whereby the shaker units can follow the plan-contours of the plants

14. A coffee harvester according to claim 13, comprising means biasing the units towards the centre line of the machine.

15. A coffee harvester according to any one of the preceding claims wherein a frame of the machine is arranged so that the machine can strad dole a row of plants.

16. Acoffeeharvesteraccordingto any one of the preceding claims comprising support wheels steerable by steering means and hydraulic cylinders connecting the wheels to the frame for adjusting the height of the harvester frame relative to the ground, the steering means being operative through the cylinders without affecting the height adjustment facility.

17. A coffee harvester according to claim 15, comprising two conveyor means disposed one on either side of the harvester centre line and arranged to catch beans detached by the respective shaker units, motion of the upper, operative run of each conveyor being arrested relative to the plants by driving the conveyor synchronously with forward motion of the machine, but in the opposite direction.

18. A coffee harvester according to any one of the preceding claims comprising guide means at the forward end ofthe harvester arranged to lift low lying branches of plants encountered by the harvester.

19. A coffee harvester according to any one of the preceding claims comprising brake means operative on a shaft of each shaker unit to prevent wind-milling ofthe unit.

20. A coffee harvester comprising at least one rotary, tined, shaker unit, drive means for oscillating the tines of the shaker unit with an oscillatory motion having a characteristic such that the acceleration from the point of zero velocity is greater than that of a sine wave, and the tines being arranged as a plural ityofarrays along the axis of the oscillations, the tines of the various arrays being inclined at at least two different angles relative to the axis of the osciilations.

21. The combination of an agricultural tractor and at least one shaker unit including a plurality of arrays of tines spaced along an axis, means for oscillating the arrays about said axis with an oscillatory cycle in which the acceleration from the point of zero velocity is greater than that of a sine wave.

22. A coffee harvester comprising at least one rotary, tined shaker unit, drive means for oscillating the tines of the or each unit with an oscillation about the longitudinal axis of the unit with a characteristic giving from the point of zero velocity an acceleration greatherthan that of a sine wave and means mounting the unit or units on the framework of the harvester for movement towards and away from the longitudinal centre line of the harvester

23. A coffee harvester comprising at least one rotary, oscillatory shaker incorporating a plurality of arrays of tines with each tine extending generally radially from an axis about which the oscillations are generated and means for imparting to the tines an oscillatory motion with a rate of maximum acceleration in each cycle of at least 509.

24. A coffee harvester comprising at least one rotary, oscillatory shaker incorporating a plurality of arrays oftines with each tine extending generally radially from an axis about which the oscillations are generated, means for imparting an oscillatory motion to the tines and means for mounting the arrays of tines, as a whole, so that they are movable towards and away from a longitudinal axis of the harvester.

25. A coffee harvester substantially as hereinbefore described with reference to the accompanying drawings.

26. A coffee harvester comprising means for shaking coffee beans from the plants by an oscillatory motion, said means being operative to generate a maximum acceleration in an oscillatory cycle of at least 509.

27. A coffee harvester comprising means for shaking coffee beans from the plants by an oscillatory motion, said means being operative to generate an oscillatory motion with an acceleration from the zero velocity point of each cycle in excess of the corresponding acceleration of a sine wave.