Abstract
A sod harvester for harvesting a slab of sod present on a piece of land, includes an arrangement for releasing the slab of sod from the piece of land and a conveyor for conveying the slab of sod in a transport direction towards a roll-up mechanism for automatically rolling up the slab of sod, wherein the roll-up mechanism includes a moving surface that moves in a direction opposite to the transport direction, wherein the conveyor conveys the slab of sod to provide that the leading end of the slab of sod abuts the moving surface, and wherein the conveyor and moving surface are spatially arranged to provide that the slab of sod and the moving surface abut while forming an acute angle.
Claims
1. A sod harvester for harvesting a slab of sod present on a piece of land, the sod harvester comprising: an arrangement for releasing the slab of sod from the piece of land; a roll-up mechanism for rolling up the slab of sod; a conveyor for conveying the slab of sod in a transport direction towards the roll-up mechanism for automatically rolling up the slab of sod; wherein the roll-up mechanism comprises a moving surface that moves in a direction opposite to the transport direction, wherein the conveyor conveys the slab of sod to provide that a leading end of the slab of sod abuts the moving surface, and wherein the conveyor and moving surface are spatially arranged to provide that the slab of sod and the moving surface abut while forming an acute angle.
2. A sod harvester according to claim 1, wherein the conveyor and moving surface are spatially arranged to enclose the slab of sod during roll-up, and wherein the transport speed of the conveyor is higher than the speed of the moving surface.
3. A sod harvester according to claim 1, wherein the conveyor adjacent the roll-up mechanism is inclined upwardly in the transport direction.
4. A sod harvester according to claim 1, wherein the acute angle is between 10 and 80.
5. A sod harvester according to claim 1, wherein the acute angle is between 15 and 60.
6. A sod harvester according to claim 1, wherein the acute angle is between 20 and 40.
7. A sod harvester according to claim 1, characterised in that wherein the acute angle is between 25 and 35%.
8. A sod harvester according to claim 1, wherein the moving surface is part of a continuous belt.
9. A sod harvester according to claim 1, wherein the moving surface is provided with one or more profiles directed towards the slab of sod.
10. A sod harvester according to claim 1, wherein the moving surface is part of a rubber track.
11. A sod harvester according to claim 1, wherein the roll up mechanism is provided with a pressure roller to direct the moving surface towards the slab of sod.
12. A sod harvester according to claim 1, wherein the conveyor and roll up mechanism are adapted to convey and roll up at least two parallel slabs of sod that are harvested at the same time.
13. A sod harvester according to claim 12, wherein the roll up mechanism comprises at least two separate moving surfaces, each moving surface corresponding to one slab of sod.
14. A dynamic roll-up mechanism for automatically rolling up a slab of sod for use in a sod harvester, the dynamic roll-up mechanism comprising a conveyor for conveying the slab of sod in a transport direction towards a moving surface that is arranged to move in a direction opposite to the transport direction, wherein the conveyor is spatially arranged with respect to the moving surface such that: conveying of the slab of sod leads to a leading end of the slab of sod coming into an abutting relationship with the moving surface, and the slab of sod abuts the moving surface while forming an acute angle therewith.
15. A method for automatically rolling up a slab of sod in a sod harvester, the method comprising the steps of: conveying the slab of sod in a transport direction with a conveyor towards a moving surface that moves in a direction opposite to the transport direction, spatially arranging the conveyor and the moving surface such that a leading end of the slab of sod abuts the moving surface while forming an acute angle therewith, grabbing the leading edge of the slab of sod with the moving surface such that the leading edge is temporarily moved in conjunction with the moving surface in said opposite direction, whereby the leading end is automatically released from the moving surface and moves towards the slab of sod to start the rolling up of the slab of sod, thereby creating a rolled up part of the slab of sod and a non-rolled up part of the slab of sod, continuing rolling up the slab of sod by conveying the non-rolled up part of the slab of sod in the transport direction, while the moving surface keeps moving the rolled up part of the slab of sod in conjunction with the moving surface in the opposite direction until the slab of sod is in essence completely rolled up.
16. A sod harvester according to claim 7, wherein the acute angle is around 30.
Description
EXAMPLES
[0030] FIG. 1 represents a sod harvester as known from the prior art.
[0031] FIG. 2 shows the conveying and roll-up set up for a sod harvester according to the invention.
[0032] FIG. 3 is a close up view of a dynamic roll-up mechanism according to the invention.
[0033] FIG. 4 is a side view of the conveying and roll-up mechanism as shown in FIG. 2, showing a slab of sod positioned with its leading edge in the dynamic roll-up mechanism.
[0034] FIG. 5 corresponds to FIG. 4, but the slab of sod being rolled up to for a larger part.
[0035] FIG. 1
[0036] FIG. 1 represents a sod harvester as known from the prior art. A sod (turf grass) is a living organism that must be handled properly to ensure its survival when it is removed from one location and transplanted to another. Sod is generally harvested using large machinery such as sod harvester 100 shown in FIG. 1. Sod harvester 100 is in the form of a self-propelled tractor and includes as a release means for the slabs of sod a cutting head 101 that cuts the slabs of sod from the land, inclined conveyor(s) 102 that elevate the slabs from the ground towards a stacking conveyor 103 (for temporarily stacking the conveyed slabs), a stacking head 105 that is mounted to a support mechanism 104, and a pallet dispenser 106 that is positioned adjacent a pallet support (not visible) on which stacking head 105 stacks slabs that it has removed from stacking conveyor 103. Two general types of harvesters exist: slab harvesters and roll harvesters. A roll harvester forms the slabs of sod into rolls which are then accumulated on the stacking conveyor for pick up. A slab harvester, on the other hand, directly stacks the slabs in their flat form. Prior art sod harvester 100 represents a slab harvester. However, the only principle difference is that a roll harvester (which is also the harvester of the present invention) includes a roll up mechanism downstream of the initial conveyer(s).
[0037] FIG. 2
[0038] FIG. 2 shows the conveying and roll-up set up for a sod harvester according to the invention. Basically, this can be the same harvester as depicted in FIG. 1, or any other known or yet to be devised sod harvester. In the shown system the conveying section comprises four parallel separate initial conveyors 102 and the same number of parallel roll-up mechanisms 110, each roll up mechanism corresponding to one of the conveyors 102. The transport direction of the slabs of sod is indicated with arrow A.
[0039] The system is provided with a control system for automatically controlling the angular position of the end or flap of a roll of sod about the roll, such as a system as known from U.S. Pat. No. 7,021,584 (as mentioned in the background section). In this system (not shown as such in FIG. 2) a device senses the end, or trailing edge, of a slab of sod after the roll is formed in a roll-up mechanism on a roll-up conveyor. The system holds the roll at the roll-up conveyor as it continues to roll and ejects the roll from the roll-up conveyor in a manner responsive to the position of the trailing edge of the strip of sod.
[0040] FIG. 3
[0041] FIG. 3 is a close up view of a dynamic roll-up mechanism 110 according to the invention. In the lower right corner of FIG. 3, the conveyor 102 for transporting the slab of sod 120 in the transport direction A is shown. The conveyor is arranged such that the slab is transported upwardly in the direction of mechanism 110. The mechanism 110 comprises a frame 122 to which a moving surface 121 in the form of a continuous rubber track is connected, the track circulating over toothed rollers 123, 124 and 125 in the indicated direction B. The teeth of the rollers penetrate trough the surface of the belt to provide for profiles at the outer circumference of the belt. The frame 122 is suspended using coil springs and dampers, to urge the belt stably towards the conveyors 102 and 202. Next to this, pressure roller 125 further urges the moving surface 121 towards conveyor 202. The lower moving surface of the track 121 (opposite to conveyors 102 and 202) moves opposite to the transport direction A. This is an important feature of the automatic roll-up mechanism of the invention. Another essential part is that the conveyor 102 and moving surface 121 are spatially arranged to provide that the conveyor conveys the slab of sod 120 to provide that the leading end of the slab of sod 120 abuts the moving surface while forming an acute angle therewith. In this example, the angle is 30. This way, upon conveying the slab of sod in the direction A, the moving surface with its profiles grabs the leading edge of the slab of sod such that the leading edge is temporarily moved in conjunction with the moving surface in a direction opposite to the transport direction A, thus initiating roll up process. Shortly thereafter, due to the influence of gravity the bent back leading end is automatically released from the moving surface and moves towards the surface of the slab of sod lying on conveyors 102/202 to fully start the rolling up of the slab of sod, thereby creating a rolled up part of the slab of sod and a non-rolled up part of the slab of sod. The conveyor 202 and moving surface 121 are spatially arranged to enclose the slab of sod during roll-up, at the site of roll-up, for a reliable active roll-up process. Also, the transport speed of the conveyor 202 is higher than the speed of the moving surface. This way, by having a larger transport speed for the conveyor, there remains a net transport speed of the slab of sod while being actively rolled up by the two surfaces enclosing the end of the slab of sod. As can be seen in more detail in FIG. 4, the rolling up is continued by continuously conveying the non-rolled up part of the slab of sod in the transport direction, while the moving surface keeps moving the rolled up part of the slab of sod in conjunction with the moving surface in the opposite direction until the slab of sod is in essence completely rolled up, while being transported.
[0042] Another advantage of the present mechanism is that due to the increased length of moving surface 121, when compared to prior art transporter belts, the centrifugal forces exerted on the roll are correspondingly smaller. This way, the quality of the roll is increased.
[0043] FIG. 4
[0044] FIG. 4 is a side view of the conveying and roll-up mechanism as shown in FIG. 2, showing a slab of sod positioned with its leading edge in the dynamic roll-up mechanism, just after the rolling up process has started. As can be seen, the frame 122 is pushed upwardly to accommodate the roll-up part of the slab of sod. The speed of the conveyors 102 and 202 is so set with respect to the speed of the moving surface 121 that there is a net transport speed of the partly rolled up slab of sod in the transport direction A towards stacking conveyor 103.
[0045] FIG. 5
[0046] FIG. 5 corresponds to FIG. 4, but the slab of sod being rolled up to for a larger part, and being transport further in the direction of stacking conveyor 103 within the roll up mechanism 110. What can be seen in FIG. 5 is that there is no open space between consecutive slabs of sod. This, together with the lack of need to interrupt the transport of a slab of sod in a stopper system, leads to a substantial increase in harvesting speed, and at the same time to a substantial decrease in the risk of tearing a slab of sod in the conveying and roll of parts of the harvester.
[0047] As can be seen in FIG. 5, the conveyor 202 and moving surface 121 enclose the slab of sod at the site of roll-up at opposite sites of the (partially) rolled up slab of sod. This way an open space remains between these elements to allow transport of the slab of sod in the transport direction while being rolled-up in between the conveyor and moving surface. In this case the conveyor and moving surface at the site of roll-up in essence run in parallel: right after the initiation of the roll-up they run at an angle of 0, which angle gradually increases with the roll becoming thicker to about 20.
[0048] Also, the suspension system of the roll up mechanism 110 enables the completion of a rolling up process of a downstream slab of sod at the exit adjacent the stacking conveyor, while at the same time initiating the roll up of the next upstream slab of sod at the entry site of the roll-up mechanism adjacent the conveyor 102. This is because the frame can move in vertical direction as a whole, but also be tilted to move roller 124 downwardly while at the same time moving roller 123 upwardly. Also, the vertical position of each of the rollers can be controlled to a certain extent independent of the position the frame takes.
