Patent Publication Number: US-6336311-B1

Title: Gang-type rotary lawn mower with rear roller

Description:
This is a continuation of U.S. patent application Ser. No. 08/794,141, filed Feb. 3, 1997, now U.S. Pat. No. 6,047,530. 
    
    
     BACKGROUND OF THE INVENTION 
     The invention relates to rotary lawn mowers and to gang-type lawn mowers. 
     Historically, reel mowers have been used to cut golf course roughs. It is generally recognized that rotary mowers are better suited for cutting tall grass, where scalping is not a problem, while reel mowers are better for shorter cutting. A gang of reels can be either attached directly to the frame on which the operator rides, or pulled behind a tractor. Pull-behind or tow-behind rotary gangs are also known. These can be driven either by a power takeoff or by a separate engine. Tow-behind gangs, whether reel or rotary, are generally undesirable for cutting a golf course rough because close trimming is difficult. Thus, rotary mowers have not been used to cut golf course roughs, which require close trimming and the ability to cut undulating terrain at a relatively short length. 
     SUMMARY OF THE INVENTION 
     The invention provides a gang-type rotary lawn mower suitable for cutting a golf course rough. This is a tremendous improvement over the known prior art, because a rotary mower typically requires substantially less maintenance than a reel mower. The lawn mower has single-spindle cutting decks attached directly to the frame on which the operator rides, with a front row of two or more cutting decks in front of the front wheels, and with a rear row of one or more cutting decks between the front and rear wheels. The invention also provides an improved arrangement for mounting a rotary cutting deck on a lawn mower frame. Each deck is mounted on its own lifting arm so that the deck can move vertically relative to the frame and can pivot relative to the frame about three mutually perpendicular axes. 
     More particularly, the invention provides a gang-type rotary lawn mower comprising a frame supported by front and rear wheels, an operator&#39;s seat mounted on the frame, at least two side-by-side front cutting deck assemblies mounted on the frame in front of the front wheels, and at least one rear cutting deck assembly mounted on the frame behind the front wheels and in front of the rear wheels. Each of the front and rear deck assemblies includes a pair of laterally-spaced, generally vertically-extending side plates, front wheels supporting the side plates for movement over the ground, and a rear roller extending between the side plates and supporting the side plates for movement over the ground. Each deck assembly also includes a single-spindle cutting deck located between the side plates and in front of the roller, the deck being mounted on the side plates such that the height of the deck relative to the ground is adjustable. The roller extends across substantially the entire width of the deck. The roller resists scalping and stripes the grass, both of which are aesthetically desirable. 
     Each deck assembly is connected to the frame by a generally L-shaped, horizontally-extending lifting arm operable to lift the deck assembly relative to the frame. Each deck assembly is connected to the frame by its own lifting arm. Each lifting arm has an inner end pivotally connected to the frame. A cross member is mounted on the outer end of the lifting arm for pivotal movement about a generally vertical axis and about a generally horizontal axis extending in the forward-rearward direction. One end of the cross member is connected to one of the deck assembly side plates for pivotal movement about a generally horizontal, laterally-extending axis adjacent the forward ends of the side plates, and the other end of the cross member is connected to the other side plate for pivotal movement about the same axis. 
     This construction enables the lawn mower to cut the undulating terrain of a golf course rough and to be controlled for close trimming. Also, as mentioned above, the lawn mower requires much less maintenance than the reel mowers historically used to cut a golf course rough. 
     Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims and drawings. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a top plan view of a lawn mower embodying the invention. 
     FIG. 2 is a perspective view of a cutting deck assembly. 
     FIG. 3 is a top plan view of the cutting deck assembly. 
     FIG. 4 is a side elevational view of the cutting deck assembly. 
     FIG. 5 is a rear elevational view of the cutting deck assembly. 
     FIG. 6 is a view taken along line  6 — 6  in FIG.  3 . 
    
    
     Before one embodiment of the invention is explained in detail, it is to be understood that the invention is not limited in its application to the details of the construction and the arrangements of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. 
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A lawn mower  10  embodying the invention is illustrated in FIG.  1 . Except as described below, the lawn mower  10  is identical to the lawn mower disclosed in U.S. patent application Ser. No. 08/787,389, filed Jan. 22, 1997, titled “PARALLEL-SERIES FOUR-WHEEL-DRIVE HYDRAULIC CIRCUIT FOR A RIDING LAWN MOWER” and assigned to the assignee hereof. The lawn mower  10  comprises a frame  12  (partially shown in FIGS. 2-5) supported by front wheels  14  and rear wheels  16  for movement over the ground. While the illustrated lawn mower  10  is rear-steering and has four-wheel drive, it should be understood that the invention is applicable to front-steering or two-wheel-drive lawn mowers. 
     The lawn mower  10  further comprises a power source  18  supported by the frame  12 . The power source may be any type known in the art, such as a gasoline-powered, internal-combustion engine. The engine drives a hydraulic pump (not shown) that supplies hydraulic fluid to hydraulic motors (not shown) drivingly connected to the wheels  14  and  16 . The lawn mower  10  further comprises an operator&#39;s seat  20 , and a conventional steering system, including a steering wheel  22 , enabling the operator to steer the lawn mower  10 . In the illustrated construction, the steering system is hydraulic and is connected to the rear wheels  16  to steer the lawn mower  10 . 
     The lawn mower  10  further comprises front and rear rows  26  and  30 , respectively, of cutting deck assemblies  34 . More particularly, in the illustrated construction, the lawn mower  10  has three side-by-side front cutting deck assemblies  34  in front of the front wheels  14 , and two rear cutting deck assemblies  34  behind the front wheels  14  and in front of the rear wheels  16 . As is known in the art, each rear deck assembly  34  is aligned with the gap between two adjacent front deck assemblies  34 . 
     Each of the cutting deck assemblies  34  includes (see FIGS. 2-5) a single-spindle mulching deck  38  defining a downwardly opening space  42  (FIG.  4 ). The deck  38  is located between and supported by a pair of laterally-spaced, generally vertically-extending side plates  46  and  48 . The term “lateral” is used herein to mean the direction from one side of the lawn mower to the other, i.e., perpendicular to the forward-rearward direction. Two front wheels  50  rotate about an axle  54  (FIGS. 2 and 3) extending between the side plates  46  and  48  in front of the deck  38 , such that each front wheel  50  supports one of the side plates  46  and  48  and the deck  38  for movement over the ground. A rear roller  58  extends between the side plates  46  and  48  and also supports the side plates  46  and  48  and the deck  38  for movement over the ground. The roller  58  is behind the deck  38  and extends across substantially the entire width of the deck  38 . The roller  58  resists scalping and stripes the grass. 
     The deck  38  is mounted on the side plates  46  and  48  such that the height of the deck  38  relative to the ground is adjustable. In the illustrated construction, the deck  38  includes spaced deck plates  66  and  68  (FIGS. 3 and 5) extending upwardly adjacent the side plates  46  and  48 , respectively. The upper end of each side plate  46  or  48  has thereon (see FIG. 2) generally horizontal, inwardly-extending ears  69  and  70 , with the ear  69  adjacent the front of the side plate and the ear  70  adjacent the rear of the side plate. Fixed to the ears  69  and  70  of each side plate  46  or  48  is an elongated plate member  71  having outwardly-extending ears  72  and  73  respectively secured to the ears  69  and  70  by suitable means such as bolts or screws  74 . Each side plate  46  or  48  and the corresponding plate member  71  has therein (see FIGS. 4 and 6) a series of holes  76 . Each of the deck plates  66  and  68  has therein several vertically-spaced series of holes  78 . Bolts  80  extending through holes  76  in the side plates  46  and  48  and in the plate members  71  and through holes  78  in the deck plates  66  and  68  secure the deck  38  to the side plates  46  and  48 . The height of the deck  38  is adjusted by changing the holes  78  in the deck plates  66  and  68  and/or the holes in the side plates  46  and  48  and in the plate members  71  through which the bolts  80  extend. 
     A single spindle  84  (FIG. 4) is mounted for rotation about a generally vertical axis within the space  42  defined by the deck  38 . The spindle  84  is driven by a hydraulic motor  88  on top of the deck  38 . The above-mentioned pump supplies hydraulic fluid to the motor  88 . It should be understood that other means could be used to drive the spindle  84 . 
     A set of cutting blades is mounted on the spindle  84  for rotation therewith. In the illustrated construction, as shown in FIGS. 3 and 4, each blade set includes a lower, leading blade  92  and an upper, trailing blade  96 . The leading blade  92  has a leading cutting edge and an upwardly angled trailing edge or lift. Preferably, the lift of the leading blade  92  is angled upwardly at an angle of approximately forty-five degrees. The trailing blade  96  has a leading cutting edge for cutting clippings deflected upwardly by the lift of the leading blade  92 . The blades are preferably identical to those disclosed in U.S. patent application Ser. No. 08/787,383, filed Jan. 22, 1997, titled “ROTARY LAWN MOWER MULCHING DECK” and assigned to the assignee hereof. In alternative embodiments of the invention, different blade arrangements can be employed. 
     Each of the deck assemblies  34  is mounted on the frame  12  by a generally L-shaped, horizontally-extending lifting arm  112 , such that each deck assembly is mounted on its own lifting arm  112 . The lifting arm  112  has (see FIGS. 2 and 3) a laterally-extending inner leg  116  with an inner end connected to the frame  12  for pivotal movement about a generally horizontal axis  120  extending in the forward-rearward direction. The arm  112  also has an outer leg  124  extending in the forward-rearward direction. A cross member  128  is mounted on the outer end of the outer leg  124  for pivotal movement about a generally vertical axis  132  and about a generally horizontal axis  136  extending in the forward-rearward direction. Each of the opposite, laterally-spaced ends of the cross member  128  has thereon (see FIGS. 2,  3 ,  5  and  6 ) a downwardly and slightly rearwardly extending arm  140 . The lower end of one arm  140  is connected to the side plate  46  for pivotal movement about a generally horizontal, laterally-extending axis  144  adjacent the forward ends of the side plates  46  and  48 . The lower end of the other arm  140  is connected to the side plate  48  for pivotal movement about the axis  144 . 
     A hydraulic assembly  148  (partially shown only in FIG. 5) connected between the arm  112  and the frame  12  pivots the arm about the axis  120  for lifting and lowering the deck  38 . When the deck is lowered for cutting, the hydraulic assembly allows the lifting arm to “float” thereby allowing the deck  38  to move vertically relative to the frame  12 . The connection of the deck  38  to the arm  112  via the cross member  128  allows the deck  38  to pivot relative to the frame  12  about the three mutually perpendicular axes  132 ,  136  and  144 . This mounting arrangement enables the deck  38  to adjust to undulating terrain, thereby substantially avoiding scalping. 
     It should be understood that the lawn mower  10  could have only two or more than three cutting decks in the front row, and only one or more than two cutting decks in the rear row. Also, other arrangements could be used to mount the decks on the frame  12 . 
     Various features of the invention are set forth in the following claims.