Abstract:
A traction enhancement system and method of using the same for use with a turf mower having a vehicle frame, a first drive wheel operably mounted to the vehicle frame, and a cutting unit positionable in a first position, where the cutting unit is support by ground engaging rollers, and a second position, where the cutting unit is support by the vehicle frame. A traction system is then operably coupled between the cutting unit and the vehicle frame such that the traction system can modulate the cutting unit between the first position and the second position for improved traction of the first drive wheel.

Description:
FIELD OF THE INVENTION 
   The present invention relates to turf mowers and, more particularly, relates to a traction enhancement system for turf mowers. 
   BACKGROUND OF THE INVENTION 
   As is well known in the art, turf mowers are often used for maintenance in varying topographical environments, such as field mowing, lawn mowing, golf course maintenance, and the like. These turf mowers are typically riding-type and include at least one mowing deck suspended for the vehicle frame. The mowing deck is movable between a raised non-cutting position, often used during vehicle travel from one cutting area to another to avoid hitting obstacles such as curbs and stones, and a lowered cutting position. Conventional mowing decks often employ decks wheels and/or rollers which serve to support the mowing deck on the ground in this lowered cutting position. Consequently, the weight of the mowing deck is carried by these deck wheels and/or rollers. This arrangement ensures that a constant and consistent cut height is maintain during the cutting operation. 
   Many riding turf mowers are equipped with mechanisms for positioning the mowing deck to a desired cutting height. Most of these mechanisms consist of linkages interconnecting the mowing deck and a lever, which is directly controlled by a hydraulic or electric actuation system. The actuation system is often controlled by the operator&#39;s hand or foot. 
   Operators of these turf mowers must often traverse slippery and/or inclined terrain during the cutting operation, when the mowing deck is in the lowered cutting position. Depending upon the slope of the grade or the condition of the turf, many known turf mowers exhibit loss of traction in the drive wheel in such situations, which complicate or even prevent cutting of some difficult areas. 
   Accordingly, there exists a need in the relevant art to provide a turf mower having improved traction performance. Furthermore, there exists a need in the relevant art to provide a traction enhancing system for a turf mower to improve operation thereof. Still further, there exists a need in the relevant art to provide a turf mower that is capable of overcoming the disadvantages of the prior art. 
   SUMMARY OF THE INVENTION 
   According to the principles of the present invention, a traction enhancement system is provided having an advantageous construction and method of use. The traction enhancement system is ideally for use with a turf mower having a vehicle frame, a first drive wheel operably mounted to the vehicle frame, and a cutting unit positionable in a first position, where the cutting unit is support by ground engaging rollers, and a second position, where the cutting unit is support by the vehicle frame. A traction system is then operably coupled between the cutting unit and the vehicle frame such that the traction system can modulate the cutting unit between the first position and the second position for improved traction of the first drive wheel. 
   Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
       FIG. 1  is a perspective view of a first turf mower employing a traction enhancement system according to the principles of the present invention; 
       FIG. 2  is a schematic view of the traction enhancement system according to the principles of the present invention; 
       FIG. 3 . is a schematic view of an operator control panel; and 
       FIG. 4  is a perspective view of a second turf mower employing the traction enhancement system according to the principles of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   The following description of the preferred embodiment is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
   With reference now to the figures,  FIG. 1  is a general illustration of a mower  10  incorporating a traction enhancement system  12  of the present invention. Although the invention is described with respect to the preferred embodiment, those skilled in the art will recognize that other versions of the mower  10  are possible and that the invention is not limited to any specific embodiment. 
   In the embodiment shown in  FIG. 1 , mower  10  generally includes three wheels  20 ,  22 , and  24  operably mounted to a vehicle frame  14 . Two front drive wheels  20  and  22  are powered by a drive motor  26 . Rear wheel  24  is positioned behind and between front drive wheels  20  and  22  and is pivotable to steer mower  10 . In the present embodiment, a plurality of mowing decks or cutting units  28 ,  30 , and  32  are provided. It should be understood that the present invention is not limited to reel-type or rotary-type mowing decks. The present invention could be used with any one of a number of available cutting units while still remaining within the spirit and scope of the invention. 
   Still referring to  FIG. 1 , cutting units  28 ,  30 , and  32  generally are positioned ahead of each wheel  20 ,  22 , and  24 , respectively. Of course other positions are possible. Cutting units  20 ,  22 , and  24  are mounted on lift arms  34 ,  36 , and  38 , which are in turn operably coupled to a lifting actuation system  40  ( FIG. 2 ). Lifting actuation system  40  may be either hydraulically or electrically operated. The operator selectively raises and lowers lift arms  34 ,  36 , and  38  depending on which cutting unit the operator wishes to use or to service. Each cutting unit  20 ,  22 , and  24  is preferably individually actuatable to provide varying cut heights. 
   Cutting units  20 ,  22 , and  24  each include a plurality of ground rollers  42 , which are adapted to engage a ground surface. As seen in  FIG. 4 , ground rollers  42  may be wheels mounted upon cutting unit or mowing deck  20 ′. In operation, when cutting units  20 ,  22 , and  24  are positioned in the lowered cutting position, the plurality of ground rollers  42  engage the ground surface and support a substantial portion of the weight of cutting units  20 ,  22 , and  24 . 
   As best seen in  FIG. 2 , traction enhancement system  12  is illustrated schematically to provide a general overview of its structure. However, it should be appreciated that traction enhancement system  12  may be varied to provide additional features or utilize different control and/or data acquisition techniques. With particular reference to  FIG. 2 , traction enhancement system  12  includes the aforementioned lifting actuation system  40 , which is operably coupled to cutting units  28 ,  30 , and  32  via control lines  44 ,  46 , and  48  and lifting arms  34 ,  36 , and  38 , respectively. Lifting actuation system  40  is either hydraulically or electrically operated to produce a lifting force sufficient to raise each cutting unit  28 ,  30 , and  32  from a lowered cutting position (shown in  FIG. 1 ) to a raised transport (non-cutting) position. Preferably, lifting actuation system  40  is capable of positioning each cutting unit  28 ,  30 , and  32  individually at any position between the lowered cutting position and the raised transport position to provide varying cutting heights. 
   Still referring to  FIG. 2 , traction enhancement system  12  further includes a pair of wheel sensors  50  and  52  operably coupled to drive wheels  20  and  22 . The pair of wheel sensors  50  and  52  are operable to detect a spin rate of each drive wheel  20  and  22  and output a signal to a modulation controller  54  via lines  56  and  58 , respectively. Modulation controller  54  in turn compares the signals of wheel sensors  50  and  52  to sense drive wheel slippage. 
   When drive wheel slippage is detected, modulation controller  54  outputs a modulating signal to lifting actuation system  40  via a line  60 . The modulating signal preferably commands lifting actuation system  40  to raise at least one cutting unit  28 ,  30 , and  32 . Specifically, this raising of at least one cutting unit  28 ,  30 , and  32  is preferably sufficient to transfer the weight of cutting unit  28 ,  30 , and/or  32  to vehicle frame  14 , but without raising cutting unit  28 ,  30 , or  32  so much as to change the cutting height. In other words, the modulating signal preferably commands lifting actuation system  40  to transfer the weight of cutting unit  28 ,  30 , and/or  32  to vehicle frame  14  so as to increase the overall weight of turf mower  10 . Increasing the overall weight of turf mower  10  consequently increases the downward force and, thus, the traction force of drive wheels  20  and  22 . 
   Most preferably, modulation controller  54  commands a periodic raising and lowering (or dithering) of cutting unit  28 ,  30 , and/or  32  to further increase the downward force exerted on drive wheels  20  and  22  due to the acceleration of the mass of cutting unit  28 ,  30 , and/or  32 . That is, as one recalls, force equals mass times acceleration. Therefore, by accelerating the mass of cutting unit  28 ,  30 , and/or  32 , the resultant force is greater than if the cutting unit  28 ,  30 , and/or  32  is merely supported above the ground surface. Ideally, modulation controller  54  would modulate cutting unit  28 ,  30 , and/or  32  at a predetermined frequency to provide maximized downward force. This may be accomplished via a hydraulic proportional valve or electrical switching system. This modulation or dithering preferably continues for a predetermined amount of time or until slippage is no longer detected. 
   It has been found that this predetermined modulation frequency ideally varies with the mass of the cutting units. Therefore, cutting units having a larger mass may only require a lower modulation frequency, while cutting units having a lower mass may require a higher modulation frequency. 
   Referring now to  FIGS. 2 and 3 , modulation controller  54  and lifting actuation system  40  are each configurable via an operator control panel  62 . Operator control panel  62  preferably includes a cutting unit lift lever  64  and a traction assist switch  66 . Cutting unit lift lever  64  is preferably operable to raise and lower cutting units  28 ,  30 , and  32  either collectively or individually. Traction assist switch  66  is preferably a three-position switch positionable between an ‘auto’ position, an ‘on’ position, and an ‘off’ position. In the ‘auto’ position, modulation controller  54  will continuously monitor wheel sensors  50  and  52  and upon detection of slippage will output a modulating command signal to improve traction of drive wheels  20  and  22 . In the ‘on’ position, modulation controller  54  will immediately output a modulating command signal irrespective of wheel sensors  50  and  52 . In this way, an operator can bypass wheel sensors  50  and  52  to achieve on-demand traction assist. Finally, in the ‘off’ position, traction enhancement system  12  is deactivated. 
   It should be appreciated that traction assist switch  66  may be a two-position switch positionable in any two of the three setting described above. Additionally, traction assist switch  66  may be such that it returns to a desired position either after actuation or upon ignition of turf mower  10 . 
   As best seen in  FIG. 4 , traction enhancement system  12 , indicate at  12 ′, may be used with a wide variety of turf mowers, such as zero-turning radius riding mowers  10 ′. Additionally, it should be understood that the principles of the present invention are equally applicable to other applications, such as the modulation of snow plow blades on vehicles. 
   The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.