Mower cutting unit
Continuation of U.S. patent application Ser. No. 683,292, filed Dec. 18, 1984, now U.S. Pat. No. 4,685,280, which is a continuation-in-part of U.S. patent application Ser. No. 545,971, filed Oct. 26, 1983 now U.S. Pat. No. 4,494,365. 
    
    
     BACKGROUND OF THE INVENTION 
     Grass growing as lawns, on golf course fairways and on putting and bowling greens, collectively termed turf, grows best when the thatch layer is not excessive. Thatch is the matted, often partially decaying, plant matter at the soil line. It is made up of stolons, rhizomes and horizontally growing grass blades as well as cut and decaying grass clippings. Removal of the thatch, which allows the new shoots of grass to sprout, for most lawns need not be done very often because the build-up of the plant material making up the thatch is about equal to its decay into humus. 
     The situation for closely cropped, dense turf, such as putting greens and bowling greens, is different. Such dense turf, because of the use to which they are subjected, is well fertilized so it grows fast and thick and may be cut daily for proper care. In addition to the naturally horizontally growing rhizomes and stolons, some grass and other plants grow horizontally in response to frequent mowing. The net result is fast thatch build-up which reduces the turf quality. 
     Complete removal of the thatch causes the destruction of the turf. To keep the thatch within desirable limits, the turf must be periodically renovated. This is typically done using a conventional mower attachment called a thatcher. The thatcher is used to cut a series of grooves in the turf to dislodge some of the matted organic matter. These renovation projects are expensive due to the direct cost of renovation and since the golf course must be shut down for a few days because of the temporary damage to the turf. 
     SUMMARY OF THE INVENTION 
     The present invention helps solve the problem of excessive thatch build up by lifting up and cutting horizontally growing plant material, preferably in conjunction with the normal periodic mowing, without damaging the turf. The need for periodic renovation using standard thatchers is therefore greatly reduced or eliminated. 
     One type of conventional grass mower cutting unit includes a frame supporting a horizontally mounted reel having a number of spiral blades. The spiral blades of the reel are driven by the mower&#39;s power source to cut grass passing between them and a horizontal bed knife situated below the reel. The cutting unit is supported on the ground by front and rear rollers. Adjusting the height of the front and rear rollers changes the distance the bed knife is above the turf to adjust the height of cut in a standard manner. 
     One aspect of the present invention is directed to an improvement to the above described cutting unit. In the improved cutting unit the standard front roller is replaced by an expunger cutting head and an associated drive assembly. The expunger cutting head includes a slotted expunger roller having numerous vertically oriented circular slots, also called expunger channels, defined between regularly spaced expunger discs. Immediately behind the expunger roller is mounted a knife roller. The knife roller includes numerous vertically oriented knife blades aligned with the circular slots of the expunger roller. The knife roller preferably is driven by the reel through a remotely actuated clutch. 
     As the expunger roller rolls along the turf, horizontally lying plant material is pulled or puckered up into the expunger channels between the expunger discs. The lifting or puckering up of the normally hoizontally lying plant material allows the blades of the knife roller, which is driven at a high rate of speed about its own axis, to lift and slice through the lifted plant material. 
     The expunger roller is mounted to the frame of the cutting unit while the knife roller is pivotally mounted to the expunger roller. This allows the height of the knife roller to be varied without changing the set, optimum distance between the axis of the knife and expunger rollers and also without changing the height of the expunger roller. Therefore, the position of the bed knife, which is determined by the positions of the expunger and rear rollers, is not affected by adjusting the position of the knife roller. 
     A primary advantage of the present invention is that horizontally lying grass and other plant matter is lifted up into the expunger channels, severed vertically by the expunger blades and cut horizontally by the closely following reel blades. Therefore, both vertical and horizontal plant material is cut during normal mowing so the turf is in effect groomed each time the grass is cut. This eliminates or reduces extensive and expensive reconditioning programs. 
     A significant commercial advantage is achieved by the present invention because the expunger cutting head is adaptable for use with commercially available cutting units. Therefore, a large scale redesign of such commercially available units is not required. Also, the expunger cutting head and drive assembly are suitable for marketing as an add-on kit to transform standard mower cutting units into applicant&#39;s turf grooming cutting unit. 
     The expunger cutting head is most advantageously used in conjunction with and as a part of a cutting unit, including a reel having spiral blades and a bed knife. However, under some circumstances, it may be desired to eliminate the reel and bed knife from the cutting unit. In such a case, the expunger cutting head can be marketed as part of a cutting unit or as an add-on kit. 
     Another feature of the invention is the pivotal mounting of the knife roller to the expunger roller. The expunger roller, mounted to the frame of the cutting unit, supports the front end of the cutting unit on the turf. The rear roller supports the other end of the cutting unit. Depending upon the height of the grass and other operating conditions, the knife roller can be adjusted in height without affecting either the height of the bed knife or the center line distance between the knife roller and the slotted expunger roller. The proper centerline distance between the expunger and knife rollers is thus automatically maintained. 
     Another key feature of the invention is the use of radially extending knife blades mounted about the knife roller in a reverse spiral pattern relative to the direction of spiral of the reel blades. By doing this, the various knife blades pass through the circular slots in the expunger roller in a staggered manner for smooth operation. The mower reel is driven at one end while the other end of the reel drives the knife roller. This, coupled with the reverse spiraling of the knife blades, provides a balancing torque to the other end of the mower reel so the cutting unit applies an even pressure to the turf surface. 
     A preferred way of fabricating the knife and expunger rollers is by the use of a number of knife discs and expunger discs mounted over their respective shafts. The spiral staging of the blade or blades extending from each knife disc can be achieved by the use of a staging pin extending axially from one side of the knife disc and a staging hole extending into the opposite side of the knife disc. The staging pin and hole are offset in a rotary direction by a chosen angle. When a series of knife discs are mounted over the knife roller shaft, the staging pin of one knife disc engages the staging hole of the adjacent knife disc to offset the knife blades by the chosen angle and lock the knife discs together to rotate as one. 
    
    
     Other features and advantages of the present invention will appear from the following description in which the preferred embodiment has been set forth in detail in conjunction with the accmpanying drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an overall view showing the turf grooming cutting unit of the invention mounted to a mower. 
     FIG. 2 is a left-hand side view of the cutting unit of FIG. 1. 
     FIG. 3 is an enlarged partial perspective view of the left front corner of the cutting unit of FIG. 2. 
     FIG. 4 is an enlarged isometric view of an expunger disc. 
     FIG. 5 is an exploded isometric view of a portion of the expunger cutting head shown in FIG. 3. 
     FIG. 6 is an enlarged isometric view of a knife disc showing the staging pin and the staging hole. 
     FIGS. 7A, 7B and 7C illustrate expunger discs pulling up and a knife blade severing normally horizontal plant material. 
     FIG. 8 is an end cross-sectional view of the knife roller and the expunger roller. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to FIGS. 1 and 3, a mower 2 is shown with three turf grooming cutting units 4 mounted thereto. Cutting unit 4 is a conventional mower cutting unit, such as one made by Toro Manufacturing Corp., Minneapolis, Minn. as Model No. 04400, except as modified as described below. Cutting units 4 are each powered by a hydraulic motor 6 which is supplied with hydraulic driving fluid through hydraulic lines 8 coupled to a power source on mower 2. Cutting unit 4 includes a frame 10 to which a horizontal reel 12 is mounted for rotation. Reel 12 is of conventional design and has a number of spiral blades 14 which cut vertically extending grass between the outer edges 16 of blades 14 and a bed knife 18 mounted to frame 10. The unmodified conventional cutting unit 4 includes a rear roller 20 and a front roller, not shown. 
     In the present invention the front roller found on conventional cutting units is replaced by an expunger cutting head 21 which includes a slotted expunger roller 22, a knife roller 48 and a knife roller drive assembly 96. Expunger roller 22 includes an expunger shaft 30 over which numerous expunger discs 32, shown in FIGS. 4 and 7A, are mounted. The height of the cut is adjusted by an expunger roller height adjuster 24, which is substantially identical to that used on the standard cutting unit. Adjuster 24, shown best in FIGS. 3 and 5, includes a shaft support 25 having a vertically extending threaded rod portion 26 and an enlarged lower end 27. Rod portion 26 passes through a rod housing 28 which is bolted to frame 10 by nut and bolts 19 and 29 (see FIG. 2). A knob 31 is mounted to the upper threaded end of rod portion 26. Shaft 30 is coupled to lower end 27 through an oval link 68 and a bearing 65. Link 68 includes a hole 70 and lower end 27 includes a bore 69 within which the outer race 71 of bearing 65 is housed. Bearing 65 includes a center shaft 73, one end of which is secured within an end bore 75 of shaft 30 and the other end of which passes freely through an opening 23 in lower end 27. Since expunger roller 22 replaces the front roller of a conventional cutting unit, rotating knob 26 causes expunger roller 22 to move along a vertical path 33 and thus adjust the height of cut of bed knife 18. 
     Expunger discs 32, seen best in FIGS. 4 and 7A, include a central opening 34, sized to be pressed on shaft 30, and a shoulder portion 36 having a diameter substantially less than the outside diameter of disc 32. Expunger disc 32 includes an outer diametral surface 38 and an inner diametral surface 40. Outer surface 38 includes an outer cylindrical surface portion 39 and circular arcuate portions 41. Outer surfaces 38 are those portions of roller 22 which rest on turf surface S while inner surfaces 40 define the roots of circular slots 42, also called expunger channels, defined between adjacent expunger discs 32 and extending between inner and outer surfaces 38, 40. Circular slots 42 include an outer region 43, indicated by dashed lines in FIG. 7A, having inwardly sloping sidewall portions 45 which guide the grass G into slots 42 as described below. 
     Knife roller 44 is mounted immediately behind expunger roller 22, as shown in FIG. 8. Roller 44 includes a knife roller shaft 46 over which numerous knife discs 48 are mounted. Knife discs 48, seen in FIG. 6, include a central bore 50 sized for mounting over shaft 46 and six radially extending blades 52. Knife discs 48 are mounted to knife roller shaft 46 so that blades 42 form a reverse spiral path about the axis 54 of knife roller 44, relative to the spiral direction of blades 14, as seen in FIG. 3. This spiral offset or staging is achieved by extending a staging pin 56 from one side 58 of disc 48 and providing a staging hole 60 in a shoulder 62 extending from the opposite side 64 of knife disc 48. Pin 56 is sized for complementary mating engagement within staging hole 60. Pin 56 and hole 60 are located at the same radius from axis 54 but offset at an angle 66 from one another. This angular offset causes blades 52 to form a spiral path about axis 54 as is desired for smooth cutting action. After mounting onto shaft 46, knife discs 48 are mated as one and the end knife discs 48 are secured to the shaft such as by using a suitable adhesive or with set screws. 
     Referring now to FIGS. 3 and 5, shaft 46 includes end bores 61 within which are mounted the ends of the center shaft 63 of a bearing 67. Bearing 67 is in turn housed within a hole 71 in an oval link 68 and a bore 77 in a spacer 104. A knife roller height adjuster 74, similar in construction to expunger roller height adjuster 24, is mounted to frame 10 adjacent and to the interior of adjusters 24. Adjusters 74 are used to vary the height of expunger rollers 44. Height adjuster 74 includes a cap 76 engaging the threaded end 78 of an adjuster bar 80. The lower end 82 of bar 80 is sized to fit loosely within an over sized hole 84 formed within the upper surface 86 of link 68. Bar 80 is secured within hole 84 by roll pin 88 which passes through complementary openings 89, 91 in bar 80 and link 68. 
     The position of knife roller 44 is adjusted relative to frame 10 by height adjusters 74. Vertical movement of bar 80 causes link 68 to pivot about an expunger axis 90 (since expunger roller shaft 30 is fixed in place by adjuster 24) passing through the center of hole 70. This pivotal movement is indicated by arrow 92. Therefore once the height of expunger roller 22 has been chosen, the height of knife roller 44 relative to cutting surface S is adjusted using adjuster 74 without changing the centerline distance between axes 54 and 90 and without affecting the height of bed knife 18 above surface S. 
     Because pivot member 68 pivots, in contrast with the vertical movement of shaft support 25, the point of connection between bar 80 and member 68 at roll pin 88 travels along an arc 94 during operation of adjuster 74. By making the connection between bar 80 and member 68 a pivotal one and by making hole 84 oversized, lower end 82 of bar 80 can move along arc 94 without binding. 
     Referring to FIGS. 2 and 5, knife roller 44 is driven by drive belt assembly 96. Assembly 96 includes a belt 98 which passes around a pulley 100. Pulley 100 is mounted to the outer end 102 of center shaft 63 which extends through tubular spacer 104. Pulley 100 is secured to shaft 63 by a set screw 106 to provide a driving interface between the pulley and the shaft. 
     Belt 98 is driven by a drive pulley 108 mounted to one end of the axle 110 of reel 12. Pulley 108 is operably coupled to and decoupled from axle 110 by remotely actuated clutch 112. Clutch 112 includes a solenoid assembly 114 mounted to frame 10 and a clutch unit 116 mounted between pulley 108 and the end of axle 110. Actuation of solenoid assembly 114 causes plunger 118 to extend engaging the periphery of clutch unit 116. This causes an internal sleeve, not shown, over which pulley 108 is mounted, to engage axle 110 thus driving belt 96. This clutch is an adaptation of one sold by Borg-Warner Corporation of Bellwood, Ill. as part no. EB 205-04-004. Other types of remotely actuated clutches may be used as well. A pivoting belt tensioner 120 keeps belt 96 taught regardless of the position of knife roller 44. 
     In use, nut and bolts 19 are loosened to allow adjusters 24, 74 to be manipulated. The position of expunger roller 22 is chosen using adjuster 24 according to the height of cut desired. The height of knife roller 44 is then adjusted using adjuster 74 according to the condition of the turf. Nut and bolts 19 and then tightened to secure both expunger and knife rollers 22, 44 in place relative to frame 10. During the operation of mower 2, during which hydraulic motor 6 powers reel 12, knife roller 44 is driven about its axis 54 upon the actuation of clutch 112. Expunger roller 22, which supports one end of cutting unit 4, rolls along surface S as mower 2 advances. As shown in FIGS. 7A-7C and 8, a piece of grass G, or other plant material, lying horizontally on surface S is pulled up between the rolling expunger discs 32 and into the circular slots 42 defined between discs 32. Curved sidewall portions 45 of outer regions 43 of circular slots 42 act to guide the pinched or puckered up grass G into the shape shown in FIG. 7B. In one embodiment slots 42 are about 4.5 mm wide, discs 32 have a thickness of about 3 mm and portions 45 have a radius of about 6 mm. These pinched up pieces of plant material are then pulled upright and sliced by the rapidly moving blades 52 of knife disc 48. Before the newly severed, generally upright grass segments U can lie down, they are cut between outer edges 16 of blades 14 and bed knife 18. Thus horizontally growing plant material is removed before it has a chance to build up into a thick, unhealthy thatch layer. 
     The reversed spiral staging of knife blades 52, illustrated in FIG. 3, allows for a smooth cutting action. This is in contrast with the vibration prone cutting action which would be likely if the knife blades were axially aligned. The speed of rotation of knife roller 44, the number of blades 52 and the height of knife roller 44 are all influenced by the operating conditions, particularly the grass height. 
     Cutting unit 4 is intended to be used each time the turf is cut. Old, tough and coarse rhizomes and stolons, as well as other horizontally growing plant material, are removed allowing for growth of new, healthy shoots. However, since blades 52 need not dig into the turf, damage to the turf is eliminated. In addition, since many broadleaf weeds cannot survive the action of blades 52, there is a greatly reduced need for eradication by use of herbicides when a mower using a cutting unit made according to the invention is used regularly. 
     The invention can be marketed as a kit for modifying existing cutting units. Doing so would entail minimal modifications to the existing unit other than replacing the existing front roller with expunger cutting head 21 and adding a drive assembly 96 with an associated switch for actuating clutch 112. 
     In some situations, it may be desired to eliminate reel 12 and bed knife 18 from cutting unit 4. Also, expunger cutting head 21 could be sold as a kit for use with equipment having no other grass cutting features. 
     Modification and variation can be made to the disclosed embodiment without departing from the subject of the invention as defined in the following claims. If desired, expunger roller and knife roller may each be made from metal or a suitable plastic and also may be made as a unitary piece, such as by molding or casting. The shape of blades 52 can be varied and their numbers can be increased or decreased. Also, channels 42, and in particular outer region 43, may be varied in cross-sectional shape from the disclosed embodiment.