BERRY HARVESTER

Abstract

An over the row berry harvester provides flexible cushioned elements and surfaces to limit bruising of the fruit harvested. A chassis defines a picking tunnel that passes over rows of plants. A picking system removes fruit from the plants as the harvester moves along the rows. A catching system configured to receive fruit removed from the plants. The catching system includes groups of catch assemblies with soft surfaces on each side of the picking tunnel, each of the catch assemblies at least partially overlapping adjacent catch assemblies. Each of the catch assemblies has a lightweight frame with an aperture and a membrane over molded to bond to the frame and extend across the aperture. The harvest also includes soft surfaces assemblies with membranes stretched between edge frame elements.

Claims

1. An over the row fruit harvester, comprising: a chassis defining a picking tunnel; a picking system configured to remove fruit from plants; a catching system in the picking tunnel configured to receive fruit removed from the plants, the catching system comprising: a plurality of resilient catcher assemblies on each side of the picking tunnel, each of the catcher assemblies at least partially overlapping adjacent catcher assemblies, each of the catcher assemblies being positioned with a sloping upper surface, the catcher assemblies flexing upon impact by falling fruit; each catcher assembly comprising: a substantially planar framework forming an aperture and having a mounting section; a membrane bonded to the framework, the membrane extending across the aperture, the membrane being formed of an elastomeric material supported solely by the framework.

2. The over the row fruit harvester according to claim 1, wherein the planar framework of each of the catcher assemblies comprises a monolithic frame element.

3. The over the row fruit harvester according to claim 1, further comprising a tunnel first soft surface assembly on each side of the picking tunnel laterally outward from the catcher assemblies, each of the tunnel first soft surface assemblies comprising a first soft surface membrane stretched between opposed supports and supported at edges of the first soft surface membrane by the opposed supports.

4. The over the row fruit harvester according to claim 3, wherein the first soft surface panel is tensioned by resilient cord elements.

5. The over the row fruit harvester according to claim 3, wherein the picking system comprises a pair of opposed columns of beaters, and wherein the catching system further comprises a beater soft surface assembly below each of the columns of beaters and having a resilient panel extending across an upper surface of the beater soft surface assembly, the resilient panel being sloped and supported at edges by a beater soft surface assembly frame.

6. The over the row fruit harvester according to claim 3, further comprising a tunnel second soft surface assembly proximate each side of the picking tunnel and having a resilient panel extending across an upper surface of the tunnel second soft surface assembly, the resilient panel being sloped and supported at edges by a tunnel second soft surface assembly frame.

7. The over the row fruit harvester according to claim 6, wherein the picking system comprises a pair of opposed columns of beaters, and wherein the catching system further comprises a second soft surface assembly below each of the columns of beaters and having a resilient panel extending across an upper surface of the second soft surface assembly, the resilient panel being sloped and supported at edges by a second soft surface assembly frame.

8. A catcher assembly comprising: a planar frame forming an aperture; a membrane adhering to the frame, the membrane comprising an elastomer material extending across the aperture and a portion of the planar frame, the membrane being supported solely by the frame; and a mounting portion.

9. The catcher assembly according to claim 8, wherein the planar frame comprises a monolithic frame element.

10. The catcher assembly according to claim 8, wherein the planar frame comprises an edge portion of reduced thickness surrounding the opening.

11. The catcher assembly according to claim 10, wherein the resilient material extends on opposed faces of the edge portion of reduced thickness.

12. The catcher assembly according to claim 10, wherein the framework defines a plurality of the apertures and wherein the resilient material extends across the plurality of apertures.

13. A fruit catching system for a fruit harvester, the fruit catching system comprising: a first row of overlapping catcher assemblies and a second row of overlapping catcher assemblies, the first row of overlapping catcher assemblies and the second row of overlapping catcher assemblies defining a passage for receiving plants to be harvested as the harvester travels; each of the catcher assemblies comprising: a planar frame forming an aperture; a membrane bonded to the frame, the resilient material extending across the aperture and an upper surface of the planar framework, the membrane being supported solely by the framework; and a mounting portion.

14. The fruit catching system according to claim 13, wherein the planar framework comprises a monolithic frame element.

15. The fruit catching system according to claim 13, wherein the planar framework comprises an edge portion of reduced thickness surround the aperture.

16. The fruit catching system according to claim 15, wherein the resilient material extends on opposed faces of the edge portion of reduced thickness.

17. The fruit catching system according to claim 13, wherein the frame defines a plurality of the apertures and wherein the resilient material extends across the plurality of apertures.

18. A method of making a fruit catcher assembly for fruit harvester, the method comprising: forming a framework having an aperture; inserting the framework in a mold having a space aligned with the aperture; filling the mold with an elastomer material and over molding at least a portion of the framework with the elastomer material and forming a resilient membrane extending across the aperture.

19. The method according to claim 18, wherein forming the framework comprises forming a monolithic frame element.

20. The method according to claim 19, wherein forming the framework comprises forming a monolithic frame element of nylon or polycarbonate.

21. A catch plate assembly for a fruit harvester consisting of: a substantially planar catch plate frame having a first face and a second face configured for attaching to a pivotal mount, the catch plate frame forming an aperture extending from the first face to the second face; a membrane of elastomeric material extending over the aperture and a portion of the catch plate frame, the membrane being bonded directly to the catch plate frame.

22. A catch plate assembly for a fruit harvester according to claim 21, wherein the membrane is over molded to the catch plate frame.

23. An over the row fruit harvester comprising: opposed picking assemblies; a chassis defining a picking tunnel; a first group of catch plate assemblies comprising a plurality of first catch plate assemblies, each of the plurality of first catch plate assemblies being pivotally mounted and overlapping adjacent first catch plate assemblies; a second group of catch plate assemblies comprising a plurality of second catch plate assemblies, each of the plurality of second catch plate assemblies being pivotally mounted and overlapping adjacent second catch plate assemblies; the first group of catch plate assemblies being positioned on a first side of the picking tunnel and extending inward toward and along a centerline of the picking tunnel and the second group of catch plate assemblies being positioned on a second side of the picking tunnel opposite the first side of the picking tunnel and extending inward toward and along the centerline of the picking tunnel; a left first soft surface assembly extending along and spaced laterally outward in the picking tunnel from the first group of catch plate assemblies; the first soft surface assembly having a sloping upper surface comprising a membrane supported at edges of the membrane; a right first soft surface assembly extending along and spaced laterally outward in the picking tunnel from the second group of catch plate assemblies; wherein the left first soft surface assembly and the right first soft surface assembly have a sloping upper surface comprising a membrane supported at edges of the membrane.

24. The over the row fruit harvester according to claim 23, wherein the picking system comprises a pair of opposed columns of beaters, and wherein the catching system further comprises a second soft surface assembly below each of the columns of beaters and having a resilient panel extending across an upper surface of the second soft surface assembly, the resilient panel being sloped and supported at edges by a second soft surface assembly frame.

25. The over the row fruit harvester according to claim 23, further comprising a tunnel second soft surface assembly proximate each side of the picking tunnel and having a resilient panel extending across an upper surface of the tunnel second soft surface assembly, the resilient panel being sloped and supported at edges by a tunnel second soft surface assembly frame.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Referring now to the drawings, wherein like reference letters and numerals indicate corresponding structure throughout the several views:

[0016] FIG. 1 is a perspective view of a first embodiment of a berry harvester according to the principles of the present invention;

[0017] FIG. 2 is a front elevational view of the berry harvester shown in FIG. 1;

[0018] FIG. 3 is a sectional view showing a portion of the left side of the berry harvester shown in FIG. 1;

[0019] FIG. 4 is a top plan view of a portion of the berry harvester shown in FIG. 1;

[0020] FIG. 5 is a bottom plan view of a portion of the berry harvester shown in FIG. 1;

[0021] FIG. 6 is a front right perspective view of a portion of the tunnel and catching system for the berry harvester shown in FIG. 1;

[0022] FIG. 7 is a front elevational view of the catching system shown in FIG. 6;

[0023] FIG. 8 is a top perspective view of a catch plate assembly for the berry harvester shown in FIG. 1;

[0024] FIG. 9 is a top plan view of the catch plate assembly shown in FIG. 8;

[0025] FIG. 10 is a bottom plan view of the catch plate assembly shown in FIG. 8;

[0026] FIG. 11 is a sectional view of the catch plate assembly taken along line 11-11 of FIG. 9;

[0027] FIG. 12 is a sectional view of the catch plate assembly taken along line 12-12 of FIG. 9;

[0028] FIG. 13 is a detail sectional view of the catch plate assembly shown in FIG. 11;

[0029] FIG. 14 is an exploded perspective view of the catch plate assembly shown in FIG. 8;

[0030] FIG. 15 is a top perspective view of a resilient panel assembly for the catching system shown in FIG. 6;

[0031] FIG. 16 is a bottom perspective view of the resilient panel assembly shown in FIG. 15;

[0032] FIG. 17 is a bottom perspective view of the resilient panel assembly shown in FIG. 15;

[0033] FIG. 18 is an end sectional view of the of the resilient panel assembly taken along line 18-18 of FIG. 17;

[0034] FIG. 19 is an exploded perspective view of the resilient panel assembly shown in FIG. 14;

[0035] FIG. 20 is a top perspective view of an angled panel assembly for the catching system shown in FIG. 6;

[0036] FIG. 21 is an exploded perspective view of the angled panel assembly shown in FIG. 19;

[0037] FIG. 22 is a perspective view of an angled drum catch assembly for below the picking heads of the berry harvester shown in FIG. 1;

[0038] FIG. 23 is a front elevational view of the angled drum catcher assembly shown in FIG. 21;

[0039] FIG. 24 is a side elevational view of the angled drum catcher assembly shown in FIG. 21;

[0040] FIG. 25 is a top plan view of the angled drum catcher assembly shown in FIG. 21;

[0041] FIG. 26 is a bottom plan view of the angled drum catcher assembly shown in FIG. 21;

[0042] FIG. 27 is a top perspective view of a second embodiment of a berry harvester according to the principles of the present invention;

[0043] FIG. 28 is a front elevational view of the berry harvester shown in FIG. 27;

[0044] FIG. 29 is a rear elevational view of the berry harvester shown in FIG. 27;

[0045] FIG. 30 is a right side view of the berry harvester shown in FIG. 27;

[0046] FIG. 31 is a bottom plan view of the berry harvester shown in FIG. 27;

[0047] FIG. 32 is a front right perspective view of a catching system for the berry harvester shown in FIG. 27;

[0048] FIG. 33 is a top perspective view of an angled catch assembly for below the picking heads of the catching system shown in FIG. 32; and

[0049] FIG. 34 is a bottom perspective view of the angled catch assembly shown in FIG. 32.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0050] Referring now to the drawings and in particular to FIGS. 1-5, there is shown a berry harvester, generally designated (100). The berry harvester may be an over the row type harvester with a chassis (102) forming a picking tunnel (108), such as shown for example in FIG. 2. The chassis is supported on wheels (104). The harvester (100) may include three wheels as shown or also four wheels, depending upon the application and requirements for its use. The harvester (100) includes a driver's seat (124) at an upper front portion of the harvester (100). Displays and controls (126) such as switches, a joystick and a steering wheel are easily accessible from the driver's seat (124).

[0051] The harvester (100) includes steps and ladders (132) to access various areas on the machine. Racks (134) provide for storing containers to be filled with berries. Decks (120) are typically at the rear of the machine and provide an area for storage and for workers to fill containers at a filling station (122) at each side of the harvester (100). The decks (120) may fold or include portions that fold to decrease the width of the harvester (100) for transport or storage.

[0052] In the embodiment shown, the harvester includes a picking assembly (106) with rotary picking heads (116) having orbital shaking picking battens. The battens project radially and extend into the plants to agitate the berry bushes as well as rotating and moving in an orbital type motion. It has been found that such agitation/engagement with the plants is effective in removing ripe berries while minimizing damage to the plants and harvested fruit. It can be appreciated however that the present invention is also adaptable to harvesters with other types of picking systems such as rotary picking heads with horizontal shaking battens or sway shakers. The picking assembly (106) is generally configured with the rotary picking heads opposed on either side of the picking tunnel (108). As the harvester (100) advances along rows of plants, the plants pass through and along the tunnel (108) and are engaged by the picking assembly (106) to remove the ripe berries.

[0053] Forward of the picking tunnel (108), low profile nose cones (140) provide a transitional surface to help to guide the fruiting canes or branches into the harvester tunnel (108). Moreover, cane lifters (142) aid in positioning lower branches of plants and lift them to be engaged by the orbital picking heads (116) for more efficient plant engagement. The fruit removed by the picking assembly (106) falls onto a catching system (110).

[0054] As shown, for example in FIGS. 5-7, the catching system (110) includes an opposed series of overlapping adjacent catch plate assemblies, such as catch plate assemblies (1000), mounted on each side of the tunnel (108). As shown most clearly in FIGS. 6 and 7, the picking tunnel (108) includes soft surface assemblies (150), (170) and (180) that are composed of a fabric membrane or other membrane materials that are stretched between supports at edges of the material to form a resilient trampoline type surface. The resilient surfaces of the assemblies (150, 170, 180) therefore provide a soft engagement surface for fruit that is flung against the surfaces. The resilient surfaces reduce the impact from the fruit impacting the surfaces and therefore reduce bruising of the fruit. By minimizing bruising, the quality of the berries harvested with such a mechanical harvester (100) may be marketed as fresh fruit.

[0055] In addition to providing a flexible surface onto which the fruit falls, creating an oblique angle to impact may also lessen the force from the fruit striking surfaces in the picking tunnel (108). As shown, for example, in FIGS. 4 and 5, lower portions (110, 150, 170, 180) of the picking tunnel (108) have a sloped upper surfaces. The upper surfaces provide a degree of resiliency or elasticity and absorb some of the force of the impact. The flexure of the surfaces combined with slope of the surfaces reduce or eliminate bruising to the berries due to impact after being dislodged from the bushes and falling. The slanting surfaces also help to direct the fruit to conveyors for transport for loading into trays or crates.

[0056] The catch plate assemblies (1000) extend generally toward the center of the picking tunnel (108). Each of the catch plate assemblies (1000) is generally configured as a substantially planar catch plate that pivotally mounts and is biased toward an extended position in which each of the catch plates (1000) extends generally inward and slightly rearward relative to the direction of travel, as shown in FIGS. 1 and 3-7. Moreover, individual rotational mounting allows the plate-like catch assemblies (1000) to rotate or pivot further backward and outward to follow around the berry bushes as the harvester (100) advances. The catch plates (1000) generally pivot out of the way while engaging the plants and then are biased back to their overlapping position. It can be appreciated that catch plates (1000) are mounted so that the catch plate assemblies (1000) upper surfaces have a slight slope that facilitates fruit rolling from the catch plate assemblies (1000) onto the conveyors. Moreover, the catch plate assemblies (1000) are configured to slightly nest with adjacent assemblies and partially overlap one another, both along the center line and from front to rear over adjacent catching assemblies, as shown for example in FIGS. 4, 5 and 7. The catch plate assemblies (1000) extend inward from a lower portion at each side of the picking tunnel (108), forming a peak where the ends of the catch plates (1000) slightly overlap in the center of the tunnel. With the overlapping configuration, fruit cannot fall between the catch plate assemblies (1000) and with the slightly sloped surface, fruit that falls onto the catch plate assemblies (1000) rolls outward in the tunnel onto conveyors (118). The conveyors then transport the fruit to the filling stations (122). In some embodiments, the harvester (100) may include additional conveyors or may include fans and/or a cleaning station to remove debris away from the harvested berries.

[0057] It can further be appreciated that the catch plate assemblies (1000) for the catching system (110) include upper surfaces that lessen the impact and therefore the damage to the fruit. As shown in FIGS. 8-14, the catch plate assembly (1000) includes a plate type frame (1002) and a flexible trampoline type membrane (1004) extending across a substantial portion of the frame (1002) in a trampoline like arrangement. The framework (1002) includes an outer ring (1010) that defines an aperture or a series of adjacent apertures (1006) extending through the plane of the catch plate assembly (1000) from an upper face to a lower face. Support ribs (1012) extend across the aperture and provide additional support to the frame (1002) and the membrane (1004). The frame (1002) may also be configured without ribs (1012) and only include an outer ring (1010) surrounding a single aperture (1006) with the membrane (1004 spanning across the entire aperture. The frame (1002) may be made of lightweight rigid or semi rigid materials such as Nylon or Polycarbonate. The frame (1002) provides sufficient support for the membrane (1004) while also allowing a limited flexure so as not to break or to become permanently bent from engagement with fruit plants or other obstacles. The framework (1002) is preferably a monolithic molded element and has rounded edges so that the fruit is not sliced if should the fruit fall on an exposed edge of the frame (1002). The catch plate assembly (1000) also includes a mounting portion (1008) to attach to a pivot allowing the assemblies to rotate, as occurs when engaging a plant. The catch plate assembly (1000) is wider proximate the aperture or apertures (1006) than at the mounting portion.

[0058] The flexible soft surface membrane (1004) is made from a resilient lower durometer elastomer material. The membrane (1004) is over molded to the frame (1002). The elastomer material of the membrane (1004) is chemically bonded to the frame (1002). The bonded membrane (1004) therefore attaches directly to the frame (1002) and does not require mechanical fasteners such as clamps, screws or bolts. As shown in FIG. 13, the frame may also include an edge portion (1014) having a reduced thickness compared to the surround portion of the frame (1002). The membrane (1004) is therefore over molded above and below the thin edge portion (1014). In this manner, there is a physical engagement of the membrane (1004) to the edge portion (1014) of the frame as well as chemical bonding of the membrane (1004) to the frame (1002). Moreover, the edge portion (1014) may have spaced apart protrusions (1016) that provide further engagement between the membrane (1004) and the frame (1002). It is appreciated that the elastic membrane (1000) spans the apertures (1006) and is over molded over a portion of the frame (1002) so that a majority of the exposed upper surface of the (1000) catch plate assembly is covered by the elastic membrane (1004).

[0059] The apertures (1006) allow the elastic membrane (1004) to act as a trampoline and flex slightly when struck by falling fruit. The membrane and its mounting arrangement provide for resiliency of the membrane (1004) to minimize damage and bruising of fruit falling onto the catching assemblies (1000). The trampoline like membrane (1004) is unsupported at the edges (1014) and is supported solely by the framework (1002) and is therefore able to deflect and stretch from the fruit impact to absorb some of the kinetic energy of the falling fruit. However, the membrane (1004) also provides a receiving surface that has sufficient tautness to allow fruit to roll off the catch plate assemblies (1000) to the conveyors. It can be appreciated that the shape may be varied somewhat as long as the upper surface absorbs some of the energy of the falling fruit and prevents bruising from impact and provides overlap and directs fruit toward the conveyors.

[0060] The design of the catchers (1000) eliminates multiple parts and their assembly. Moreover, the elastomer material of the membrane forms a soft trampoline surface that does not require tensioning. The catcher is reversible and can be used as a left side catcher or a right side catcher. This reduces the number of replacement catchers that are needed for maintenance and replacement. The catchers (1000) are made in an efficient molding process that uses lightweight and cost-effective materials. The material for the frame (1002) is placed in mold and then cured. The mold is then reconfigured and a volume proximate the frame corresponding the membrane is formed. The elastomer material is thin introduced into the mold. The elastomer material is then cured and chemically bond to the frame to achieve the catcher assembly (1000).

[0061] Referring to FIGS. 15-19, there is shown a tunnel first soft surface assembly, generally designated (150). The tunnel first soft surface assembly (150) includes a thin flexible membrane (152) such as food grade fabric or plastic sheet stretched over a rigid or semi-rigid frame (154). The flexible material (152) may be chemically bonded or mechanically attached to the frame (154). The level of flexibility of the membrane (152) may be changed by adjusting its tension. Changing tension is accomplished through slotted holes on the clamping mechanism (160), or by the use of rope, spring or elastic cord (156), such as bungee cords, having hooks (158) to secure the edges. A pocket may be sewn in to allow a rigid rod or sheet (162) to be inserted and engaged by the hooks (158). Mounting brackets (164) maintain the upper surface of the flexible membrane (152) at a slope, as shown in FIG. 7. As with the catcher assemblies (1000), the slope of the upper surface lessens the impact of fruit falling on the assembly (150) to prevent bruising. One tunnel first soft surface assembly (150) is spaced laterally outward of the rows of the catcher plate assemblies (1000) on the left side of the picking tunnel and a second tunnel first soft surface assembly (150) is spaced laterally outward of the rows of the catcher plate assemblies (1000) on the right side of the picking tunnel and direct fruit downward for transport to be loaded into trays or crates.

[0062] Unlike cushion designs with foam that adhere to a rigid substrate, the first soft surface assembly (150) can be easily disassembled for cleaning. Moreover, the first soft surface assembly (150) also has adjustable tension so that the cushioning performance may be optimized. Tension may be easily adjusted by interchanging elastic elements (156) of different lengths and/or different elasticities. Furthermore, rather than replacing the entire assembly (150), the flexible membrane (152) may also be easily replaced should it become worn, tear or have holes.

[0063] Referring to FIGS. 20 and 21, there is shown a second tunnel soft surface assembly comprising an angled tunnel angled panel assembly, generally designated (170). The tunnel angled panel assembly (170) includes a frame (172) supporting a membrane (174) at edges of the membrane by a trim element (176). The frame (172) positions the upper surface of the membrane (174) at an acute angle relative to the sides of the tunnel (108). Therefore, the membrane (174) requires less cushioning effect than other elements that are sloped, but more horizontal. The membrane (174) is easily replaced by removing the trim element (176) and inserting a new membrane (174). The cushioning effect of the angled tunnel panel assembly (170) may be varied by switching the membrane (174) with a different membrane composed of a different material.

[0064] Referring to FIGS. 22-26, there is shown an angled beater panel assembly, generally designated (180). The angled beater panel assembly (180) includes a frame (182) forming a partial cylinder and supporting a membrane (184) at edges of the membrane by trim elements (186). The frame (182) positions the upper surface of the beater membrane (184) at a slope. As the beaters tends to slow falling fruit, less cushioning is needed below the beaters. Therefore, the membrane (184) requires less cushioning effect than other elements. The membrane (184) is easily replaced by removing the trim elements (186) and inserting a new membrane (184). The cushioning effect of the angled beater panel assembly (180) may be varied by switching the membrane (184) with a different membrane (184) made of a different material.

[0065] A second embodiment of a fruit harvester according to the present invention is shown in FIGS. 27-31 and generally designated (200). The berry harvester (200) is also an over the row type harvester with a chassis (202) forming a picking tunnel (208). Unlike the harvester (100), the chassis (202) of the berry harvester (200) is supported on four wheels (204). The harvester (200) includes a driver's seat (224) at an upper front portion of the harvester (200). Displays and controls (226) such as switches, a joystick and a steering wheel are easily accessible from the driver's seat (224).

[0066] The harvester (200) includes a picking assembly (206) with rotary picking heads (216) having orbital shaking picking battens. Forward of the picking tunnel (208), low profile nose cones (240) provide a transitional surface to help guide the fruiting canes or branches into the harvester tunnel (108). Moreover, cane lifters (242) aid in positioning lower branches of plants and lifting them for engagement by the orbital picking heads (216) for more efficient fruit removal. The fruit removed by the picking assembly (206) falls onto a catching system (210).

[0067] The harvester (200) includes a ladder (232) to access a large upper deck (220) provide an area for storage and for workers to fill containers at filling stations (222) at each side of the harvester (200) receiving a conveyor delivering fruit from each side of the picking tunnel (208). The raised decks (220) include railings (236) and may include portions that fold to decrease the width of the harvester (100) for transport or storage.

[0068] As shown in FIG. 32, the structures of the catching system (210) in the picking tunnel (208) are similar to the structures of harvester (100). The catching system (210) of the harvester (200) includes a series of catch plate assemblies (1000) on each side of the tunnel above conveyors (218). The catching system (210) also includes a soft surface assembly (250) on each side of the tunnel (208).

[0069] Referring to FIGS. 33 and 34, each soft surface assembly (250) includes a thin flexible membrane (252) stretched over a rigid or semi-rigid frame (254). However, the columns housing the picking heads (216) of the harvester (200) have a different cross section than that of each column of the harvester (100). An angled beater panel assembly (280) includes a membrane (284) stretched over a frame (282). However, rather than forming a somewhat semi-circular assembly, the angled beater panel assembly (280) has a somewhat trapezoidal portion (286) with an added tapered portion (288) extending from one end. The membrane (284) is retained and tensioned by engagement at edges with ropes, springs or elastic cords (256) having hooks (258). The frame (282) positions the upper surface of membrane (284) at a slope. As the beaters tend to slow the descent of falling fruit, less cushioning is needed below the beaters. Therefore, the membrane (284) requires less cushioning effect than other cushioned surfaces. The membrane (284) is easily replaced by removing the hooks (256) of the elastic cords (258) and attaching a new membrane (284). The cushioning effect of the angled beater panel assembly (280) may be varied by switching the membrane (284) with a different membrane (284) made of a different material.

[0070] It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.