Height of cut adjustment system for reel mower

[0001] This invention relates generally to a height of cut adjustment system for a reel type grass cutting unit.

[0002] Reel type grass cutting units typically used on golf courses and athletic fields are designed so the height at which the grass is cut can be adjusted to various levels as desired. This is an important adjustment because the appearance and health of the turf, and the quality of the athletic activity may be affected by the cut height. Throughout the growing season, the cut height may need to be changed to suit the growing conditions. Additionally, the cut height may need to be changed for different areas. On a golf course, for example, areas such as fairways are usually cut at different heights than roughs or approaches.

[0003] On a manually adjusted reel type grass cutting unit, the height of cut adjustment is labor intensive, time consuming, and requires a high level of skill. Turf managers may not change the cut height as frequently as may be needed because of the time and work involved in the adjustment process. Many facilities will have multiple mowers, each dedicated to a specific cut height, instead of re-adjusting the height of cut of a machine.

[0004] A self-adjusting reel type grass cutting unit has been developed that sets the cut height automatically when commanded through a user interface. This adjustment system has two separate frameworks: the cutting unit frame and the ground contacting frame. A pair of adjusting screws actuated by dc electric motors may raise and lower the cutting unit frame with respect to the ground contacting frame. A four bar linkage on each end of the cutting unit frame sets the attitude of the cutting unit frame and keeps the cutting unit frame approximately parallel with the ground as the cut height is adjusted. A self adjusting reel is shown in U.S. Pat. No. 7,114,318 assigned to Deere & Company of Moline, Ill.

[0005] The self adjusting reel described above has many advantages over manually adjusting the height of cut, including savings in time, skill and effort required to make the adjustment, and high accuracy. It would be desirable to further reduce the work required to set or change the height of cut of a reel type grass cutting unit.

[0006] A height of cut adjustment system for a reel type grass cutting unit includes independent adjustment mechanisms mounted to each corner of a frame of the cutting unit. Each independent adjustment mechanism operates to raise and lower a vertical post supporting a corner of the cutting unit. Linkages between the independent adjustment mechanisms allow the posts to be raised or lowered synchronously to set the cutting height. The height of cut can be set or changed from a single adjustment point.

[0010] FIGS. 1-3 show a height of cut adjustment system 101 for a reel type grass cutting unit according to a first embodiment of the invention. The reel type grass cutting unit has a horizontal shaft 102 that rotates to turn cutting reel 103, to cut grass between the cutting reel and bedknife 104. Motor 105 may be used to rotate shaft 102, and may be electric or hydraulic.

[0011] In one embodiment, height of cut adjustment system 101 includes four independent adjustment mechanisms, each of which may be rigidly attached to and support a corner of cutting unit frame 106. The independent adjustment mechanisms may be adjustment screw mechanisms 108-11. Front ground roller 112 may be attached to the lower portion of a pair of front adjustment screw mechanisms 108-09, and rear ground roller 113 may be attached to the lower portion of a pair of rear adjustment screw mechanisms 110-11. The opposing ends of the front and rear ground rollers may be rotatably mounted to the lower portions of the adjustment screw mechanisms so that the ground rollers may rotate as they roll across the turf and support the cutting unit at a desired cutting height.

[0012] In one embodiment, each adjustment screw mechanism 108-11 can change the position of a vertical post 121-24 mounted to the end of a ground roller. Each post 121-24 can move vertically up or down within a sleeve 116-19 rigidly mounted to a corner of the cutting unit frame.

[0013] In one embodiment, each post 121-24 can move vertically up or down within a sleeve 116-19 by turning an adjustment screw 126-29. Each adjustment screw 126-29 includes externally threaded screw shaft 175-78 and worm gear 164-67. Externally threaded screw shaft 175-78 engages internal threads in an axial bore through post 121-24. Worm gears 164-67, at the top end of adjustment screws 126-29, are concentric to the screw shafts. Each sleeve may be covered by a cap 171-74.

[0014] In one embodiment, each adjustment screw 126-29 may be turned by rotating worm shaft 144-47 that engages worm gear 164-67. Each worm shaft 144-47 is perpendicular to worm gear 164-67. Each worm shaft 144-47 may extend through a case 151-54 open to the side of a sleeve 116-19, so that it can engage each worm gear 164-67. Additionally, each worm shaft 144-47 may have a hex head extending out from the end of the case so that it can be gripped and turned with a wrench or power drill socket, or the worm shaft may be turned by other devices such as those described in more detail below. When viewed from above, each worm shaft 144-47 may be approximately 25 mm to the side of the worm gear axis.

[0015] In one embodiment, worm shafts 144, 146 on the left side of the cutting unit are concentric. The concentricity of worm shafts 144, 146 allow the two left adjustment screw mechanisms to be driven synchronously by connecting the worm shafts together with drive shafts 131, 133. Similarly, worm shafts 145, 147 on the right side of the cutting unit are concentric, and are connected together with drive shafts 132, 134 to allow driving the two right adjustment screw mechanisms synchronously. Shaft connectors 140 may slide over the ends of the drive shafts and worm shafts to connect them together. The shaft connectors may be removed to disconnect the shafts as necessary, so that an operator can manually preset parallelism and/or attitude of the cutting units.

[0016] In one embodiment, the adjustment screw mechanisms on the left side and right side of the cutting unit may be linked together so that all four mechanisms can be driven synchronously, to change the cut height, from a single adjustment point. For example, the mechanical linkage may be drive shaft 135 that connects between the left and right adjustment screw mechanisms. Worm shafts 148-49 may be attached to the opposing ends of drive shaft 135 using shaft connectors. Each worm shaft 148-49 may extend through a case 158-59. Each case 158-59 may be open to the side of sleeve 156-57 so that worm shaft 148-49 can engage screw gear 137-38. Screw gears 137-38 extend through sleeves 156-57 mounted to frame 106. Screw gear 137 may be connected between drive shafts 132 and 134 using shaft connectors and spacer 161. A screw gear (not shown) also may be connected between drive shafts 131 and 133 using shaft connectors and spacer 162.

[0017] Instead of drive shafts linking the adjustment screw mechanisms, the mechanical linkage may be a synchronous belt or chain drive that links the mechanisms together. Driving all four adjustment screw mechanisms synchronously allows an operator to adjust the entire cut height at one adjustment point. Alternatively, each pair of adjustment screw mechanisms (e.g., the front pair of mechanisms, and the rear pair of mechanisms) may be linked together so that each pair may be driven synchronously from one adjustment point, and the cut height may be changed from only two adjustment points.

[0018] In one embodiment, the adjustment point may be a hex head on the end of each worm shaft that may be driven by a hand wrench in a manual adjustment system. Alternatively, the adjustment point may be a hex head on the end of the worm shaft that may be driven using a portable power source such as an electric drill unattached from the cutting unit. Alternatively, as described above, the adjustment point may be driven by a power source attached to the frame of the reel cutting unit, such as dedicated electric motor 142 shown in FIGS. 1-3. The dedicated electric motor may be a DC motor mounted to cutting unit frame 106 so that it may turn drive shaft 135 and drive all four adjustment screw mechanisms synchronously. Additionally, the electric motor may be connected to a control computer and user interface as part of a self adjusting reel system.

[0019] In one embodiment, a mechanical counter may be mounted to one of the drive shafts. The mechanical counter may increment with each rotation of the drive shaft, and indicate actual cut height. For example, if adjustment screws 126-29 have a pitch of 20 threads per inch, each rotation of the adjustment screw will change the cut height 0.05 inch. If the worm gear drive ratio is 50:1, each rotation of a drive shaft 131-35 will turn the adjustment screw 1/50^th of a turn. As a result, each turn of the drive shaft will change the cut height 0.001 inch. The mechanical counter may indicate the cut height to 0.001 inch resolution.

[0020] In one embodiment, the drive ratio of the linkage that connects the drive shafts may be arranged such that the attitude of the cutting mechanism increases with increasing cutting height. For example, if the front and rear drive shafts are driven at the same rate, the front of the cutting unit may raise as the adjusting screws turn at the same rate.

[0021] The height of cut adjustment system of the present invention provides adjustment flexibility because the ground rollers can be adjusted to be parallel with each other and the bedknife. A pair of adjustment screws, or all four adjustment screws, may be linked together synchronously so that the cut height may be set or changed at one adjustment point. This reduces the work required to set or adjust the height of cut. Optionally, each adjustment point may have a mechanical and/or digital display indicating the cut height. The adjustment point may be powered by a portable electric tool, so that the adjustment may be performed quickly. Alternatively, the adjustment point may be powered by a dedicated actuator as part of a self adjusting reel system.

[0022] Having described a preferred embodiment, it will become apparent that various modifications can be made without departing from the scope of the invention as defined in the accompanying claims.