Abstract:
A cylindrical turf treatment rotor ( 10 ) adapted to be driven in rotation about a horizontal axis ( 10   a ), and provided with wear-resistant teeth ( 13 ) extending along one or more helical tracks ( 14   a - 14   d ) on the rotor, the teeth being individually attacked to the rotor so as to be capable of individual removal for replacement or refurbishing or for reconfiguring the rotor.

Description:
FIELD OF THE INVENTION 
     This invention relates to implements for turf treatment, more particularly for treatment of sports playing surfaces such as football, rugby and hockey pitches, and tennis courts which, during the course of a playing season, are subject to wear and tear and also suffer from a build-up of thatch, which is an accumulation of layers of partially decomposed leaves, stems and roots. Diseases and other blights including algae, moss, fungi, and slime mould can invade the turf, and may be made worse by the presence of thatch. 
     BACKGROUND OF THE INVENTION 
     It is usually recommended that thatch be treated by mechanical thatching equipment, an operation usually referred to as scarification, but sometimes known as verticutting, although that term is also used for the process of cutting vertically into the turf using fine blades, sometimes known as turf grooming. It is recommended to carry out scarification in several treatments rather than attempting to remove all the thatch at once, but this is essentially because conventional scarifiers remove thatch in thin furrows, leaving ‘ridges’ of thatch between them, and so cannot remove all the thatch in one pass. 
     U.S. Pat. No. 6,094,860 discloses the use of artificial fibre reinforcement for grass turf areas in playing fields subject to heavy wear, and other patents and proprietary systems similarly involve the use of artificial fibre reinforcement. 
     “Desso® Grassmaster” is a turf reinforcement system in which artificial grass fibres are injected some 20 cm deep into a grass surface, projecting some 25 mm above the soil. The maintenance of this system, as regards mowing, verticutting and ventilating, is said to be no different from the maintenance of ordinary turf. Mowing, of course, must be carried out with the cutter height at or above the height of the artificial grass fibres, e.g. at 26 mm or more if the fibre height is 25 mm, otherwise they would be cut or pulled out. 
     The artificial grass fibres are injected into a matrix of sand, which of course has no nutritional value, and there is only a thin top layer of humus, if indeed any, so the natural grass needs to be treated with fertiliser more than it would if grown in deep soil. This exacerbates problems of disease and infestation, bearing in mind that about 97% of the turf is natural grass. The sand also, over the course of a playing season, compacts more than does the usual substrate of natural, unreinforced turf. 
     On this, or indeed any, turf, moreover, undesired grasses and weeds such as clover can be a problem. Clover is especially problematic on playing surfaces such as tennis courts, as it tends to be slippery. Weeds are usually treated with systemic herbicides, which take time to act and which may require several treatments over a space of weeks. 
     SUMMARY OF THE INVENTION 
     The present invention provides an improved apparatus for treating turf, including artificial grass-reinforced turf planted in a matrix of sand and/or soil, that is capable of removing thatch, diseased or blighted humus and sand, even all of the grass and weeds without, however, affecting the artificial grass reinforcement, if present. 
     The invention comprises a cylindrical turf treatment rotor adapted to be driven in rotation about a horizontal axis, and provided with wear-resistant teeth extending along one or more helical tracks on the rotor, the teeth being individually attached to the rotor so as to be capable of individual removal for replacement or refurbishing or for reconfiguring the rotor. 
     The teeth may be removably attached to blades fixed on the rotor. The teeth may be bolted on to the blades, and may be attached by a single bolt, the blades having recesses or so arranged in relation to adjacent blades as to define a recess into which the teeth fit so as to be held securely in position by a single bolt. 
     The blades may be fixed in slots, which may be laser-cut, in the rotor, and may be welded in the slots. 
     The teeth may have tips extending at least 60 mm above the cylindrical surface of the rotor. 
     The tips may extend up to 200 mm above the cylindrical surface of the rotor. 
     The teeth may be of wear resistant material or at least tipped with wear resistant material such as tungsten carbide. 
     The teeth may extend on four equally spaced helical tracks, and blading may be provided for four tracks. 
     With teeth closely spaced along each of four helical tracks, and set to an appropriate depth of penetration of the teeth, the rotor will be capable of removing in one pass all or substantially all thatch, grass and infected humus and/or sand. In this configuration, it will be capable of treating Desse® Grassmaster reinforced turf without disturbing the reinforcing fibres, leaving the ground ready for reseeding. Reconfigured to have two tracks only, by removing the teeth from two tracks of blading, it will function as a scarifier, removing thatch to a desired depth but leaving turf. In this configuration it will be suitable for treating ordinary, unreinforced turf. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A cylindrical turf treatment rotor according to the invention will now be described with reference to the accompanying drawings, in which: 
         FIG. 1  is a perspective view of one embodiment of rotor; 
         FIG. 2  is a front elevation of the rotor of  FIG. 1 ; 
         FIG. 3  is an end-on view of the rotor of  FIG. 1 ; 
         FIG. 4  is a close-up view of teeth on the roller of  FIG. 1  showing a first attachment scheme; 
         FIG. 5  is a close-up view of teeth on the roller showing a second attachment scheme; 
         FIG. 6  is a view of a single tooth for the scheme illustrated in  FIG. 5 ; and 
         FIG. 7  is a rear view of a rotor in use. 
     
    
    
     DETAILED DESCRIPTION 
     The drawings illustrate a cylindrical turf treatment rotor  10  adapted to be driven in rotation about a horizontal axis—axle  10   a —and provided with teeth  13  extending along one or more helical tracks  14  on the rotor  10 , the teeth  13  being individually attached to the rotor  10  and connected to adjacent teeth  13 , the teeth  13  having tips  13   a  extending at least 60 mm above the cylindrical surface of the rotor  10 . 
     The tips  13   a  may extend up to 200 mm above the cylindrical surface of the rotor. 
     The teeth  13  may extend on four equally spaced helical tracks  14   a ,  14   b ,  14   c ,  14   d.    
     The teeth  13  are removably attached, so that they may be replaced or refurbished when worn or damaged in use and so that the rotor  10  may be reconfigured. With teeth  13  closely spaced along each of four helical tracks  14 , the rotor  10  will be capable of removing in one pass all or substantially all thatch, grass and infected humus and/or sand, but with two tracks only, it will function as a scarifier, selectively removing thatch to a desired depth. 
     In the embodiment shown particularly in  FIG. 4 , the teeth  13  fit into slots in the rotor  10  surface and are locked in place by connecting members  16  connecting them to adjacent teeth  13 . 
     In the embodiment shown particularly in  FIGS. 5 and 6 , the teeth  13  are bolted, with a single bolt  13   a , to blades  17  welded into slots laser-cut into the rotor surface. The blades  17  have recesses or are so arranged in relation to adjacent blades as to define a recess into which the teeth fit so as to be held securely in position by a single bolt  14 . 
     The teeth  13 , as better seen in  FIG. 6 , are generally trapezoidal in shape 
     The teeth  13  may be of wear resistant material, but, as illustrated, are of steel tipped with wear resistant material  13   a  such as tungsten carbide. 
     In use, as shown in  FIG. 7 , the rotor  10 , not shown per se in this Figure, but mounted in a chassis  42 , is drawn over turf  11 , by a tractor  41 . The chassis  42  has a ground roller  43  and a blade height control arrangement  44  adapted to deploy the teeth  13  below turf level  14 . The tractor  41  is driven to traverse the rotor  10  over the turf so deployed and has a power take-off transmission  45  to rotate the rotor  10  so that the blades  13  move through the turf  11  pulling out thatch, natural grass  12  and matrix material, soil and/or sand. The rotor  10  is driven so that the teeth  13  drive into the turf  11  as it moves forward. The material lifted from the turf is driven to the right of the tractor  41  by the action of the helically disposed teeth  13  and is lifted on an elevator  45  into a trailer  46  drawn behind a second tractor  47 . 
     As shown, the rotor  10  has teeth of sufficient depth and density that they can, using rotor height control arrangement  45 , remove all or substantially all thatch, grass and diseased matrix, leaving a friable surface onto which fresh seed may be sown. A roller of, say, one metre breadth, may thus treat a football or like sized field on a single pass, two passes at most, an operation comfortably accommodated within a single day&#39;s work. 
     If the rotor  10  is reconfigured by removing teeth from two of the helical tracks—opposite helices, so as to leave the rotor balanced—and deployed, using the height control, so that the teeth penetrate to a lesser depth, the rotor  11  will constitute an effective scarifier, giving a less drastic treatment. 
     In either configuration, the rotor  10  will leave artificial grass turf reinforcement, such as Desso Grassmaster® reinforcement, unaffected.