Abstract:
A rotary cutting deck for a mower includes a cutting deck supported by wheels at three of the four corners of the deck. The other corner of the cutting deck, namely a corner of the deck that is close to the mower, is supported by a corner suspension that lifts upwardly with a biasing force sufficient to elevate that corner of the deck above the ground. This corner suspension takes the place of the caster wheel that would normally support this corner of the deck, and thus permits the deck to be moved closer to the side of the mower, thus reducing overall mower width without decreasing the width of the cutting swath.

Description:
TECHNICAL FIELD 
     This invention relates to a rotary cutting deck for a mower. More particularly, this invention relates to a suspension for elevating at least one corner of the cutting deck above the ground, thereby eliminating the need for a wheel to support that corner of the cutting deck. 
     BACKGROUND OF THE INVENTION 
     Mowers are known for mowing large areas of grass, such as those in parks, golf courses, athletic fields, and the like. Many such mowers comprise a self-propelled traction frame that is part of a vehicle on which the operator sits as the mower is operated. At least one cutting deck, and often a plurality of cutting decks, are attached to the traction frame to cut a swath of grass as the traction frame moves forwardly. In a typical configuration, such a mower often has a front cutting deck extending forwardly of the traction frame and two side or wing cutting decks extending laterally from the sides of the traction frame. 
     The cutting decks are normally equipped with ground engaging wheels to allow the cutting decks to roll over the ground as the traction frame moves forwardly. A lift arm extends between the traction frame of the mower and the cutting deck to allow the cutting deck to be selectively lifted off the ground and placed in a transport position. In the case of the wing decks, the transport position comprises one in which the wing decks are folded up against the sides of the traction frame. When the cutting decks are not so lifted off the ground and placed in their transport position, they roll over the ground and “float” relative to the traction frame to allow the cutting decks to follow the ground contours. 
     In some prior art designs, the wing decks on such a mower are supported by a pair of outrigger wheels attached to the wing deck adjacent the outer front and rear corners of the wing deck. The inner front and rear corners of the wing deck carry no wheels at all. Instead, whatever support is provided from The traction frame, such as the lift arm, is used to keep the inner front and rear corners of the wing deck elevated above the ground. U.S. Pat. No. 5,715,667 to Goman et al. shows wing decks of this type, i.e. wing decks supported by only a pair of outrigger wheels on the outer corners of the frame and a support arm extending from the traction frame. 
     In decks of the type just described, the Applicants have found that using just a single pair of outrigger wheels on the outside of the wing deck presents problems in achieving a consistently good quality of cut. It should be kept in mind that such wing decks often cut over hilly, uneven terrain in which the wing deck rolls about a longitudinal axis through the wing deck. The Applicants have found that when cutting over this type of terrain, the lack of inner support wheels results in a variation in the height of cut over the width of the path being cut by the wing deck. In other words, the grass cut over the inside of the cutting deck might be cut higher or lower than the grass being cut over the outside of the cutting deck where the support wheels provide a more consistent height of cut. Since this variation in the height of cut can often be seen with the naked eye and detracts from the appearance of the cut grass, it is a disadvantage and desirably should be avoided. 
     Some mowers are known in which the wing deck is supported by wheels adjacent all the corners of the deck. The Applicants have found that this avoids the height of cut variation described above when only a pair of support wheels are used. However, using four support wheels adjacent each corner of the deck has problems of its own. 
     First, at least some of the support wheels are typically caster wheels, i.e. wheels capable of pivoting about a vertical support axis as they roll over the ground. Because of the varied and uneven terrain over which the mower operates, all of the support wheels, and particularly the caster wheels, wear quickly and must be periodically replaced. This is a disadvantage. 
     Moreover, it is desirable that a particular mower be as narrow as possible when the mower has the cutting decks placed in their transport position with the wing decks folded up along the sides of the mower. By minimizing the width of the mower in its transport configuration, the mower is more maneuverable and also fits within as tight a space as possible. This requires that the wing decks be close to the traction frame. When caster wheels are used on the inner corners of the wing decks, these caster wheels may be too close to the frame to avoid interfering with the frame. Thus, the wing deck must typically be moved out from the frame a little further than the designer might prefer in order to accommodate the inner caster wheels. Again, this also is a disadvantage. 
     SUMMARY OF THE INVENTION 
     One aspect of this invention relates to a rotary cutting deck for a mower. The cutting deck has at least one rotary cutting element rotating about a substantially vertical axis in a substantially horizontal cutting plane when the cutting deck and rotary cutting element are in operation. The cutting deck when coupled to the mower has two corners that are closest to the mower and two corners that are furthest from the mower. A plurality of spaced support wheels are carried adjacent at least the two corners of the cutting deck that are furthest from the mower. A corner suspension is connected to at least one of the two corners of the deck that are closest to the mower. The corner suspension comprises at least one upwardly biased connecting link attached to the at least one corner of the cutting deck, the bias on the connecting link being sufficient to elevate the at least one corner of the cutting deck above the ground without using a support wheel adjacent the at least one corner. 
     Another aspect of this invention relates to a rotary cutting deck for a mower. The cutting deck has at least one rotary cutting element rotating about a substantially vertical axis in a substantially horizontal cutting plane when the cutting deck and rotary cutting element are in operation. An attachment is provided on the cutting deck for coupling to a pivotal lift arm extending laterally outwardly from one side of the mower. The cutting deck when so coupled to the lift arm has inner front and rear corners that are closest to the mower and outer front and rear corners that are furthest from the mower. Three support wheels are carried adjacent the inner front, the outer front and the outer rear corners of the cutting deck. A corner suspension comprises at least one upwardly biased connecting link attached to the inner rear corner of the cutting deck. The bias on the connecting link is sufficient to elevate the inner rear corner of the cutting deck above the ground without using a support wheel on the inner rear corner. 
     Yet another aspect of this invention relates to a rotary cutting deck for a mower. The cutting deck has four corners. Ground engaging wheels are located adjacent three of the four corners of the deck. A corner suspension is provided for the fourth corner of the deck. The corner suspension includes an upwardly biased connecting link acting between the mower and the fourth corner of the deck. The connecting link is biased to lift upwardly on the fourth corner of the deck with a biasing force sufficiently strong to elevate the fourth corner of the deck above the ground. The corner suspension takes the place of a ground engaging wheel on the fourth corner of the deck. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     This invention will be described hereafter in the Detailed Description, taken in conjunction with the following drawings, in which like reference numerals refer to like elements or parts throughout. 
     FIG. 1 is a perspective view of a rotary cutting deck according to this invention, particularly illustrating the deck installed as a wing deck extending laterally to one side of the traction frame of a mower; 
     FIG. 2 is an enlarged perspective view of a portion of the rotary cutting deck of FIG. 1, particularly illustrating the corner suspension for elevating one corner of the cutting deck in lieu of a support wheel; and 
     FIG. 3 is an enlarged top plan view of a portion of the rotary cutting deck of FIG. 1, particularly illustrating the corner suspension for elevating one corner of the cutting deck. 
    
    
     DETAILED DESCRIPTION 
     One embodiment of a rotary cutting deck according to this invention is shown in FIGS. 1-3 with the rotary cutting deck being generally illustrated as  2 . Cutting deck  2  is of the type that is intended to be attached to a traction frame  4  of a mower  6  so that cutting deck  2  is propelled over the ground as mower  6  travels over the ground. One cutting deck  2  or multiple cutting decks  2  may be attached to mower  6 . Only a portion of mower  6  is shown in FIG. 1, namely a portion of traction frame  4  and one of the front drive wheels  8  of mower  6 . 
     Cutting deck  2  houses or carries one or more rotary cutting elements (not shown), such as rigid blades, that rotate in substantially horizontal cutting planes about substantially vertical axes. A hydraulic motor  10  may be mounted on top of cutting deck  2  for providing power for rotating the cutting elements carried within a cutting chamber on the underside of cutting deck  2 . Other power sources for rotating the cutting elements can be used. 
     Cutting deck  2  is shown as a wing deck attached to one side of traction frame  4  of mower  6 . As is well known in the art, a lift arm  12  attaches cutting deck  2  to traction frame  4 . An outer end  14  of lift arm  12  is pivotally coupled to an attachment  18  at the approximate center of cutting deck  2  by various pivot joints  16   a,    16   b,  and  16   c  that permit pitching, rolling, and yawing of cutting deck  2  about the three x, y and z axes of an xyz coordinate system. Instead of the separate pivot joints  16   a - 16   c  shown, a single ball joint could be used to provide the same motion for cutting deck  2 . An inner end  20  of lift arm  12  is connected to traction frame  4  by a pivot shaft  22 . 
     A hydraulic cylinder  24  is provided on traction frame  4  for selective operation by the operator of mower  6 . This cylinder is connected between traction frame  4  and inner end  20  of lift arm  12  to pivot lift arm  12  upwardly and downwardly about pivot shaft  22 . This will raise and lower cutting deck  2  between its substantially horizontal cutting position (shown in FIG. 1) and a raised generally upright transport position (not shown) in which cutting deck  2  has been folded up along the side of traction frame  4 . Thus, lift arm  12  is used for moving traction frame  4  between its operating and its transport positions. Lift arm  12  also serves to propel cutting deck  2  as traction frame  4  of mower  6  is driven over the ground. 
     In addition to lift arm  12 , a second support arm  26  extends between traction frame  4  and a rear portion of cutting deck  2 . This second support arm comprises a shock absorber for bi-directionally absorbing impact shocks and resisting the yawing action of cutting deck  2  about the vertical pivot axis. The details of the shock absorber comprising the second support arm  26  are, inter alia, the subject of another patent application assigned to the assignee of this invention, namely U.S. Ser. No. 09/507,313, which is copending herewith. 
     Referring to FIG. 1, cutting deck  2  has three support wheels adjacent three corners of cutting deck  2 . There is an inner front support wheel  28  adjacent the inner front corner of cutting deck  2 , and outer front support wheel  30  adjacent the outer front corner of cutting deck  2 , and an outer rear support wheel  32  adjacent the outer rear corner of cutting deck  2 . The two front support wheels  28  and  30  are not caster wheels but are rotatable support wheels that rotate about pivot shafts that do not themselves rotate about vertical axes. The outer rear support wheel  32  comprises a caster wheel that is capable of rotating about a substantially vertical pivot axis  34 . 
     Each of the support wheels  28 ,  30  and  32  can be adjusted relative to cutting deck  2  to change the height of cut. This is done in generally conventional ways known in the art. For example, the front support wheels  28  and  30  can be adjusted up and down by virtue of various support pins received in one of a plurality of adjustment holes  34  provided on the height of cut mechanism. The rear caster wheel is provided with a rotatable adjustment knob  36  which, when rotated, raises and lowers the yoke  38  that supports the rear caster wheel. The precise type of height adjustment mechanism used in conjunction with the support wheels can be varied. 
     A corner suspension is provided for the remaining corner of cutting deck  2  to keep this corner elevated above the ground during operation of cutting deck  2  without having to use a support wheel at that corner. The corner suspension is indicated generally as  40  in FIGS. 1-3. Corner suspension  40  acts on the inner rear corner of cutting deck  2 . 
     As shown in FIGS. 1-3, corner suspension  40  acts between cutting deck  2  and a portion of second support arm  26  that overlies cutting deck  2 . Since second support arm  26  is pivotally connected at either end to cutting deck  2  and traction frame  4 , second support arm  26  will move up and down with cutting deck  2  as cutting deck  2  floats and follows the ground contours. By locating corner suspension  40  on that portion of second support arm  26  overlying cutting deck  2 , the location and placement of corner suspension  40  is simplified with corner suspension  40  also moving generally in concert with cutting deck  2 . 
     Corner suspension  40  comprises a bellcrank  42  that is pivotally mounted on a pivot rod  44  that is carried on second support arm  26 . A generally vertical connecting link  46  extends between one arm of bellcrank  42  and the inner rear corner of cutting deck  2 . The lower end  47  of connecting link  46  is connected to the inner rear corner of cutting deck  2  through a height adjustment mechanism  48 . Namely, lower end  47  of connecting link  46  can be pinned in one of a plurality of vertically spaced adjustment holes  50  provided on height adjustment brackets  52  carried on the inner rear corner of cutting deck  2 . In addition, the upper end  49  of connecting link  46  can be connected to one of a plurality of vertically spaced holes  54  provided on the first arm of bellcrank  42 , to further increase the number of height adjustment settings that are possible. 
     Height adjustment mechanism  48  between the inner rear corner of cutting deck  2  and connecting link  46  can obviously be varied. For example, the use of plural adjustment holes  54  on the first arm of bellcrank  42  can be deleted with the upper end  49  of connecting link  46  simply pinned to the first arm of bellcrank  42  in only one location. Secondly, connecting link  46  has its lower end  47  shown located between two height adjustment brackets  52  with its lower end  47  being pinned to both brackets. However, only one height adjustment bracket  52  could be used in place of the two brackets  52  that are shown. In addition, other height adjustment mechanisms for connecting lower end  47  of connecting link  46  to cutting deck  2  could be used. 
     The second arm of bellcrank  42  is connected to a spring  60  that extends between the second arm of bellcrank  42  and an anchor  62  that is located on second support arm  26 . Spring  60  imposes a force tending to rotate bellcrank  42  in the direction of the arrow A. See FIG.  2 . This force is thus arranged to pull up on connecting link  46 , and thus to pull up on the inner rear corner of cutting deck  2 , as shown by the arrow B adjacent connecting link  46 . Again see FIG.  2 . Spring  60  provides a biasing force which is chosen to be sufficient to keep the inner rear corner of cutting deck  2  elevated above the ground during normal cutting operation of cutting deck  2 . This force also helps keep the three support wheels  28 ,  30  and  32  in contact with the ground. 
     Using a resilient spring force to impose a load on the inner rear corner of cutting deck  2  elevates that corner of cutting deck  2  without having to use any support wheel on that corner. Thus, the caster wheel that would normally be found on that corner of cutting deck  2  can simply be deleted. This is advantageous since there is one less caster wheel that sees wear and would eventually have to be replaced. It also allows cutting deck  2  to be spaced more closely to frame  4  with no interference occurring between the caster wheel and the side of traction frame  4  when cutting deck  2  is folded up into its transport position. Accordingly, the transverse width of mower  6  can be minimized when the cutting decks  2  are raised and mower  6  is in its transport mode. 
     The Applicants have found that the above-described corner suspension  40  effectively supports the inner rear corner of cutting deck  2  without the need for any support wheel. This corner suspension  40 , in concert with the other three support wheels  28 ,  30  and  32 , allows cutting deck  2  to float and adjust to ground contours and provides an even and consistent height of cut over that swath of grass being cut by cutting deck  2 . Since all of the support wheels  28 ,  30  and  32  are desirably equipped with height of cut adjustment mechanisms, it is necessary for corner suspension  40  to also have this ability, which has been implemented by having lower end  47  of connecting link  46  connect to cutting deck  2  through a height of cut adjustment mechanism  48 . 
     In some operational conditions, it has been found that the inner rear corner of cutting deck  2  bounces up and down during operation. In order to minimize this undesired bouncing, an oil filled damper  70  is used between the second arm of bellcrank  42  and another anchor  72  on second support arm  26 . This damper  70  tends to smooth out and eliminate undesirable bouncing of cutting deck  2 . However, damper  70  could be eliminated if so desired and corner suspension  40  including spring  60  would still be useful for elevating the inner rear corner of cutting deck  2  without using a support wheel. 
     Various modifications of this invention will be apparent to those skilled in the art. While corner suspension  40  has been shown as being applied to only the inner rear corner of cutting deck  2 , a similar corner suspension could also be used on the inner front corner of cutting deck  2  in place of inner front support wheel  28 . Thus, the scope of this invention is to be limited only by the appended claims.