AUXILIARY BLADE MOWING DECK

Abstract: An improved mowing unit having two main spaced apart unsynchronized cutting blades (11, 12) followed by a smaller auxiliary cutting blade (13), the smaller auxiliary cutting blade (13) mowing the vegetation that passes through the space (24) between the two main cutting blades (11, 12).

Description: AUXILIARY BLADE MOWING DECK Field To Which Invention Relates This invention relates to mowing decks for mowers. It is especially suitable for use for smaller narrow wheel- base lawn mowers. Statement Of The Invention It is an object of this invention to eliminate the need for synchronization mechanisms in multi-blade cutting units of lawn mowers. It is an object of this invention to improve the operation of cutting units of lawn mowers. It is an object of this invention to provide for an improved cutting action in mower cutting units. It is an object of this invention to provide for a substantially balanced cut vegetation dispersion by mowing cutting units. Another object is to substantially equalize .the discharge of cut grass from dual cutting blades driven by a common source of power. Another object is to minimize the amount of uncut grass in a patch or strip intermediate dual counter rotat¬ ing blades of a cutting unit carried by, and driven by, . a tractor. It is an object of the invention to increase the servicability of mowing cutting units. It is an object of this invention to minimize the adverse effects of a full grass catcher upon the efficiency of the cutting unit. It is an object of this invention to greatly reduce the possibility of clogging of the cutting unit discharge tube with cut grass or clippings. It is an object of this invention to facilitate the clearing out of the cutting unit discharge tube from grass clippings upon the grass catcher filling up and resisting further flow of grass clippings through the tube to the catcher. OMPI ^S Othe advantages and a fuller understanding of the invention may be had by referring to the following description and claims, taken in conjunction with the accompanying drawings, in which: FIGURE 1 is a bottom view of a lawn mower cutting unit incorporating the invention of this application; FIGURE 2 is a top view of the cutting unit of FIGURE 1. This FIGURE 2 includes drive'belts; FIGURE 3 is a schematic diagram of the cutting unit of FIGURE 1.. This FIGURE 3 details the geometry of the cutting unit of FIGURE 1. FIGURE 4 is a front perspective view of the cutting unit of FIGURE 1 in combination with allied grass catchers disposed to receive cut grass from the cutting unit. FIGURE 5 is a rear perspective view of the mowing deck and allied grass catchers of FIGURE 4 as mounted on the tractor of a riding lawn mower. FIGURE 6 is an enlarged side view of the cutting unit discharge tube of FIGURES 4 and 5. FIGURE 7 is a cross-sectional view of the dis¬ charge tube of FIGURE 6 taken generally through the lines 7-7 of that FIGURE 6. FIGURE 8 is a cross-sectional view of the dis¬ charge tube of FIGURE 6 taken generally through the lines 8-8 of that FIGURE 6; FIGURE 9 is a cross-sectional view of the dis¬ charge tube of FIGURE 6 taken generally through the lines 9-9 of that FIGURE 6; FIGURE 10 is a cross-sectional view of the dis- charge tube shown in FIGURE 6 taken generally through the lines 10-10 of that FIGURE 6. FIGURE 11 is a side view of the discharge tube of FIGURE 6 mounted to the cutting unit (partially shown in broken lines) and to the grass catcher (partially shown in broken lines) of my improved lawn mower as shown in FIGURE 5. ΕE ^ OMΪI o Description of the Invention Herein Disclosed The cutting unit incorporating the preferred form of the invention of this application has a deck 10 , a first rotary cutting blade 11, a second rotary cutting blade 12 and an auxiliary rotary cutting blade 13. See FIGURE 1. The deck 10 may be a casting or may be a stamping. The first rotary cutting blade 11, disposed be¬ low the deck 10, is rotatably connected at its axis of rotation to the deck 10 by .means of a bearing 16 carried by deck 10. A drive shaft 15 extends through the drive bearing 16 and deck 10 to protrude above the deck 10. A drive pulley 17 (see FIGURE 2) is fixedly attached to the upper protruding end of the drive shaft 15. The first rotary cutting blade 11 is rotated in a counter-clockwise direction as illustrated by arrows (when viewed from below as in FIGURE 1) . The opposite ends of the cutting blade 11 are denoted as 11A and 11B. During rotation, the tips 11A, 11B of the blade 11 define a tip circle 18 shown in dotted lines in FIGURE 1. The second rotary cutting blade 12 is rotatably connected at its axis of rotation to the deck 10 by a second shaft 19 extending through bearing 20 carried by deck 10. The drive shaft 19 extends upwardly through the bearing 20 and above the deck 10 to protrude above the top of the deck 10. A second drive pulley 21 is fixedly attached to the protruding upper end of the drive shaft 19. The second rotary cutting blade 12 is rotated in a clockwise direction as illustrated by arrows (when viewed from below as in FIGURE 1) . The opposite ends of cutting blade 12 are denoted as 12A and 12B. During rotation, the tips 12A, 12B of the blade 12 define a tip circle 22 shown in dotted lines. A line 23 extending through the axis of rotation of the first 11 and second 12 rotary cutting blades is substantially perpendicular to the normal direction of forward cutting travel of the tractor carrying the cut- ting unit. The tip circles 18, 22 of the first 11 and second 12 rotary cutting blades, respectively, are spaced apart a relatively small distance indicated by the refer¬ ence character 24 in FIGURE 1. Ordinarily this space 24 between circles 18 and 22 would leave an unmowed strip of grass remaining on an otherwise mowed lawn. In the invention of this applica¬ tion a small auxiliary or supplemental cutting blade 13 mows the strip of grass. This auxiliary cutting blade 13 is located rearwardly from line 23 through the axes of shafts 15 and 19. The axis of blade 13 is parallel to the axes of shafts 15 and 19. In the normal forward travel of the cutting unit (upwardly in the views of FIGURES 1 and 2) , the rearward supplementary blade follows the two blades 11 and 12. The auxiliary rotary cutting blade 13, also on the underside of deck 10, is rotatably connected at its axis of rotation to the deck 10 by a third shaft 25 ex¬ tending through bearing 26 mounted on deck 10. The drive shaft 25 extends through the bearing 26 and deck 10 to protrude upwardly above the deck 10. A third drive pulley 27 is fixedly attached to the upwardly protruding end of the drive shaft 25. The auxiliary rotary cutting blade 13 is rotated in a counter-clockwise direction as illustrated by arrows (when viewed from below as in FIGURE 1) . During rotation, the tips 13A, 13B at the opposite ends of auxiliary rotary cutting blade -13, define a tip circle 28 shown in a dotted line in FIGURE 1. The tip circle 28 of the auxiliary rotary cutting blade 13 is spaced equidistantly from the tip circle 18 of the first cutting blade 11 and from the tip circle 22 of the second cutting blade 12. The first ' cutting blade 11 and second cutting blade 12 are rotatably driven by a single main drive belt 29 which is driven by pulley 30. The pulley 30 is rotated by power from the tractor upon which the cutting unit is mounted. (See FIGURE 2) In order to provide for counter- rotation a small idler pulley 31 is rotatably connected to the deck 10 in a manner to reverse the direction of rotation of the second cutting blade 12 relative to the direction of rotation of blade 11. The blades 11 and 12 are thus counter-rotatable. The drive belt 29 extends from the engine driven pulley 30 about the drive pulley 17 of the first cutting blade 11, around the idler pulley 31 and around the drive pulley 21 driving the second cutting blade 12. A second auxiliary drive belt 32 drivingly connects the drive pulley 17 of the first cutting blade 11 to the drive pulley 27 of the auxiliary or supplemental cutting blade 13. The drive pulley 27 is of a smaller diameter than the drive pulley 17. The ratio between these pulleys 17-27 is chosen such that the auxiliary blade 13 has a tip speed substantially equal to the tip speed of the main cutting blades 11, 12. The relative sizes and locations of the first blade li . second blade 12 and auxiliary blade 13 are geometrically inter-related as seen in FIGURE 3. The tip circle 18 of the. first rotary cutting blade 11 and the tip circle 22 of the second rotary cutting blade 12 are spaced apart at location 24. A line 23 is shown extending through the axis of rotation (drive shaft 15) of the first cutting blade 11 and the axis of rotation (drive shaft 19) of the second cutting blade 12. The axis of rotation (drive shaft 25) of the auxiliary cutting blade 13 is located on a line 33 running perpendicular to the line 23 through the first 11 and second 12 cutting blade axes. OMPI < The auxiliary cutting blade 13 is at least of a size such that it cuts or mows all of the unmowed strip of vegetation that passes through the space 24 between the first 11 and second 12 cutting blades. This size of supplemental blade 13 is determined by a consideration of the tip circles 18, 22 in combination with the point and minimum radius of turn of the cutting unit mounted on a law mower tractor when making a turn. When the cutting unit is carri'ed on a tractor which powers the unit through pulley 30 when in operation, 0 there will be a pair of laterally spaced points 34 about which the mowing unit will turn in a turning radius (one point for left hand turn, one point for right hand turn) . These points preferably are in-line with line 23, for ex¬ ample points A or B, or elsewhere, for example points C. 5 If the mower tractor turns symmetrically, these pair of points 34 will also be symmetrical. If the tractor doea not turn symmetrically, the pair of points- 34 will also not be symmetrical. When the tractor to which the cutting unit is at¬ 0 tached turns about a given point 34, the place where the respective tip circles 18 , 22 contact space 24 will trace an arc 35. The arc 35 is centered about the point 34. The arc 35 has a radius sybstantially equal to the dis¬ tance between the point 34 and the place where the re¬ 5 spective tip circle 18, 22 contact space 24. For example, in FIGURE 3, if the tractor turned in one direction about point 34Athe arc would be arc 35A. While if the tractor turned in the same direction about point 34B, the arc would be arc 35B. 30 The auxiliary cutting blade 13 is sized such that its tip circle 28 intersects or at least contacts the arc 35. With such a size auxiliary cutting blade 13, there would be no unmowed strip passed by the cutting unit under any normal mowing conditions. ^ 5 it is preferred that the auxiliary or supplemental cutting blade 13 be slightly longer than necessary to merely contact these arbitrary circles 35A, 35B. This increased size would insure the mowing of all vegetation covered by the mowing deck. The larger size would also enable the rotative speed to be reduced. The auxiliary blade 13 should be rotated at a speed generally matching the cutting tip speed of the main cutting blades 11, 12. It is also preferred that the axis of rotation (drive shaft 25) of the auxiliary blade 13 be in ad- vance of a line 36 tangent to both of the tip circles 18 and 22. Such a location keeps the mowing deck com¬ pact, and all blades as close together as possible with¬ out interfering with each other. Please note that the auxiliary cutting blade 13 could be located in advance of the main cutting blades 11, 12. The functions of the auxiliary cutting blade 13 could also be performed by more than one auxiliary cutting blade. These derivations would, however, increase the load on the auxiliary cutting blade and/or increase the complexity of the mowing unit. Due to the space at location 24 between the tip circles 18, 22 of the main cutting blades 11, 12 in combi¬ nation with the auxiliary mowing blade, it is unnecessary to synchronize the main cutting blades 11, 12. There is no need for expensive synchronization mechanisms such as gear drives, timing belts, and the like. The main cutting blades.11, 12 rotate without interference because of their being spaced apart and located as shown. By rea¬ son of the structure and arrangement shown, severe torque loads (such as hitting a stump with a blade) can be ab¬ sorbed by the blades of the cutting unit without adverse effects. The mowing deck 10 itself is designed with dual spiral deep deck air flow shapes, as seen ' in FIGURE 4. Each of these dual air flow shapes tapers from an initial OMPI location 37 to a discharge opening 38, one on each lateral side of the unit (see also FIGURES 1 and 2) . Two tubes 39 connect the discharge openings 38 to two grass catchers 40 carried by the tractor at its rear end. The two tubes 39 are of a unique structure and highly efficient form (see FIGURES 6-11) . The tubes 39 each include an intake port 42 followed by a closed and confined section 43, Thereafter, the tube 39 has an open bottom section 44 open to atmosphere along its length. The tube 39 has discharge port at its end opposite of intake port 42. The intake port 42 of each tube 39 extends into the discharge opening 38 of the mowing deck 10 to form a unitary discharge path for the cuttings or clippings. Notches 46 in the tube 39 accommodate and fit over a rod 47 that is attached to the mowing deck 10. This notch 46- rod 47 interconnection maintains each tube 39 in position . in respect to a discharge opening 38. A small extension part or tongue 48 extends into the deck 10 adjacent and along the bottom edge of the discharge opening 38 of cutting unit 10. This tongue 48, as a threshold sill, insures the efficient discharge of the cuttings or clip¬ pings from the mowing deck 10 into the tubes 39. (See FIGURE 11) . After the intake port 42, the tube 39 has a closed section 43 of gradually decreasing cross sectional area. The bottom of this section 43 of the tube 39 is closed by plate 49. This gradually decreasing section 43 serves to accelerate the speed of the cuttings or clippings. This section 43 also directs the cuttings (as well as rocks and foreign matter) upwardly in the tube 39. The tube 39 then has an open bottom section 44. This section 44 guides the cuttings towards the discharge port 45 of the tube 39. The open space at the bottom of section 44 is denoted by the reference character 50. Due to the speed and initial direction of the cuttings upon entry into this section 44, a full bottom plate or closing is unnecessary to provide for an efficient passage of cuttings or clippings along this section 44. The depth of section 44 increases slightly from its junction with the closed section 43 to the discharge port 45 (contrast FIGURE 8 with FIGURE 10) . This increase in depth compen¬ sates for the loss of momentum of the cuttings or clippings along the length of the section 44. The discharge port 45 of the tube 39 protrudes a short distance into the grass catcher 40. A small plate 51 extending between the sides of the tube 39 holds them apart. The tube 39 itself rests on a transverse rod 52 carried by the grass catcher 40 extending across the bottom of the entrance opening into the grass catcher 40. The incorporation of an opening in section 44 of . ; the tube 30 reduces the possibility .of clogging of the tube 39. If the grass catcher 40 associated with a tube 39 becomes full and hence resists further flow of grass cuttings or clippings through the tube into the catcher, the excess cuttings being discharged from the cutting unit 10 are permitted to fall down through the open space 50 in the bottom of section 44 and to be discharged onto the ground rather than to clog the tube. (And in the un¬ likely event of clogging the open space 50 in the bottom of section 44 allows the tube 39 to be cleared in place without removal of the tube 39 from the tractor) . The open section 44 allows the tractor to efficiently mow with a full grass catcher 40 by having excess grass clip¬ pings readily fall to the ground without resistance to discharge of clippings from the cutting unit 10. The cutting action of the mower is unimpeded by the fact that the grass catchers 40 are already filled with clippings. When the grass catcher 40 is removed, an automatic OMPI ^ * plate (not shown) may be mounted to close the discharge port 45 of the tube 39. Due to the open section 44 of the tube 39 allowing grass clippings to fall to the ground when resistance is met to flow of clippings from the dis- charge port 45, the mowing efficiency of the tractor is not compromised if the tractor is operated with the grass catcher 40 removed. The counter rotating main cutting blades 11, 12 combine with the dual spiral air flow shape of the mowing unit 10 to produce an even and steady cutting and dis¬ charging action. ' Both cutting blades operate independ¬ ently of the other. One blade is not under greater ten¬ sion or work load than the other as in normal single dis¬ charge port decks having two blades. The mowing deck 10 of this invention, the tubes 39 and the two grass catchers 40 are shown in FIGURE 5 mounted on a lawn mower tractor 41. Each of the two grass catchers 40 can -be independently removed from the lawn mower 41 and emptied. Two automatic plates (not shown) deflect the mowing clippings downward in the event of operation of the lawn mower 41 when the grass catchers are removed. Although this invention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the pre¬ ferred form has been made only by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and the scope of the invention as hereinafter claimed.

Claims: WHAT IS CLAIMED IS: 1. In a cutting unit mountable on a tractor of a grass mower, the cutting unit having a deck with dis¬ charge ports disposed on opposite lateral sides thereof and air flow toroidal chambers formed in the deck lead¬ ing to said discharge ports, respectively, the improve¬ ment of a pair of counter rotational cutting blades, carried by the deck on opposite lateral sides thereof, said pair of cutting blades having their axes of rotation parallel to each other and laterally spaced apart to leave a space between the circles generated by the tips of the said pair of blades, upon rotation said space being sufficient in degree to avoid interference between the blades in non-synchronous driving arrangement, and a supplemental cutting blade carried by the " deck having its axis of rotation located between the said circles generated by the tips of the said pair of blades and lo¬ cated between spaced lines tangent to both said circles generated by the tips of said pair of blades, said pair of blades and said supplemental blade being rotational in unison to cut grass below the deck, the grass between the said circles being cut between said cirles being discharged into one of said toroidal chambers and hence out through one of said discharge ports. 2. The improvement claimed ' in Claim 1, and in which the axis of rotation of said supplemental cutting blade is located between spaced. lines extending laterally through the axes of the said pair of cutting blades. 3. The improvement claimed in Claim 1, and including driving means carried by the deck for rotating said pair of blades in unison with said pair of blades being in counter rotation and said supplemental blade rotating in the same direction as one of said pair of blades, said driving means being arranged to provide substantially equal rotational tip speeds for said pair of blades and said supplemental blade. OMPI 4. The improvement claimed in Claim 1, in which the circle generated by the supplemental blade upon rotation intersects or at least contacts the circle generated by one of said pair of blades upon turning of the cutting unit on a tractor in a turning direction toward the side of the unit upon which the said one of the pair of blades is carried. 5. The cutting unit of Claim 1 characterized by the addition of grass catcher means and tubes leading from said discharge ports to the grass catcher means and wherein each of the tubes have an open space in the bottom of the tube for discharge of cuttings therethrough upon resistance to discharge of cuttings into the grass catcher. 6. A grass cutting unit adapted to be carried and powered by a mower tractor, comprising the combina¬ tion of a mower deck having discharge ports disposed adjacent opposite lateral sides of the deck for dis¬ charge of cut grass from the same, the deck having downwardly disposed cavities on opposite lateral sides of said deck communicating with said discharge ports, respectively, a pair of counter-rotatable cutting blades disposed in said cavities, respectively, for cutting grass extending into the cavities and blowing the cut grass out through the said discharge ports, said pair of cutting blades being of.substantially the same length and rotatab ' le at substantially the same speed for cutting substantially the same amount of grass and blowing the same out through said discharge ports, the opposite ends of each of said pair of cutting blades generating a circle upon rotation of each of said cutting blades, a supplemental cutting blade carried by said deck adjacent a lateral border of said deck relative to forward motion of the cutting unit, said supplemental unit having alength less than half the length of each of said pair of counter-rotating blades, the opposite ends of said supplemental blade generating a circle upon rotation of the supplemental blade, the major portion of the circle generated by the supplemental blade being disposed intermediate the two circles generated by said pair of counter-rotating cutting blades, said supplemental blade cutting grass located below it and blowing the grass cut by it into one of said cavities to be blown therefrom by the cutting blade rotatable in said one cavity, and operating means carried by the- deck and powered by the said mower tractor for rotating all said blades in unison with the pair of blades in counter rotation and the supplemental blade in rotational direction corresponding to the rotational direction of one of said pair of blades, 7. The combination claimed in Claim 6 and in which the supplemental cutting blade is rotatable on an axis dis ¬ posed between spaced lines drawn tangent to both the circles generated by said pair of counter rotatable cutting blades. 8. The combination claimed in Claim 7 and in which the axis on which the supplemental cutting blade rotates is disposed on a line normal to a line drawn through the axes of said pair of counter rotating cutting blades. 9. The combination claimed in Claim 6 and in which the length of the supplemental cutting blade is less than one-third the length of each of said pair of counter- rotational cutting blades. • 10. The cutting unit of Claim 6 characterized by the addition of grass catcher means and tubes leading from said discharge ports to the grass catcher means and wherein each of the tubes has an open bottom section through which grass cuttings may fall downwardly upon resistance to passage of cuttings from the tubes into the catchers. 11. In a mowing unit movable on a longitudinal line of travel and having first and second main rotary cutting blades rotatably mounted to a deck with a line running through the axes of rotation of such first and second main cutting blades being substantially perpen¬ dicular to the longitudinal line of travel of the mowing unit, and the first and second main cutting blades generating substantially equal radii tip circles when rotated, the improvement of the tip circle of the first main cutting blade being spaced from the tip circle of the second main cutting blade by a distance less than the substantially equal radii of the tip circles and characterized by the addition of an auxiliary rotary cutting blade, said auxiliary cutting blade having an axis of rotation, said auxiliary cutting blade having tips at its opposite ends, said tips defining a tip circle when said auxiliary cutting blade is rotated about said axis of rotation, said auxiliary cutting bade being rotatably mounted to the deck of the mowing unit about said axis of rotation with said axis of rota¬ tion being located between the line running through the axes of rotation of the first and second main cutting blades and a substantially parallel second line running tangent to both of the tip circles of the first and second main cutting blades, and with said tip circle of said auxiliary cutting blade being spaced from the tip circles of the first and second main cutting blades, said auxiliary cutting blade cutting the vegetation that would otherwise pass uncut out of the mowing unit for reason of the said space between the tip circles of the first and second main cutting blades. 12. The improved mowing unit of Claim 11 charac¬ terized in that said axis of rotation of said auxiliary cutting blade is mounted to the deck of the mowing unit with the distance between said axis of rotation of said auxiliary cutting blade and the axis of rotation of the first main cutting blades being substantially equal to the distance between said axis of rotation of said auxiliary cutting blade and the axis of rotation of the second main cutting blade. 13. The improved mowing unit of Claim 12 charac- terized in that said auxiliary cutting blade is mounted to the deck of the mowing unit intermediate the " first, and second main cutting blades. 14. The improved mowing unit of Claim 13 charac¬ terized in that the first main cutting blade rotates in the opposite direction of said second main cutting blade. 15. In a mower having a tube leading from a dis¬ charge port of . a cutting unit to a grass catcher, the improvement of the tube having an opening in the bottom wall of the tube to* permit grass cuttings or clippings to fall downwardly through said opening upon resistance to discharge of cuttings from said tube into the catcher. 16. The improved mower of Claim 15 characterized in that the opening in the bottom wall of the tube extends for less than the full length of the tube and at a distance from the cutting unit. 17. The improved mower of Claim 16 characterized by the addition of means to direct the cuttings from the cutting unit towards the upper wall of the tube such that th cuttings, in absence of resistance to the discharge of cuttings from the discharge port of the tube, pass by said opening in the bottom wall of the tube to the discharge port of the tube. 18. The improved mower of Claim 17 characterized in that said means to direct the cuttings from the cutting unit towards the upper part of the tube comprises a portion having a gradually reduced cross-section in the tube, said .portion part of the tube being located between said opening in the bottom wall of the tube and the discharge port of the cutting unit. OMPI 19. The mower of Claim 18 and including a bottom wall of the tube that gradually rises from its end adja¬ cent the cutting unit to the said opening in the bottom wall of the tube. 20. An improved tube for conducting blown grass clippings from the discharge port of the cutting unit of a grass- mower to a grass catcher, the tube having an open space in the bottom wall thereof for permitting grass clippings in the tube to fall downwardly from the tube upon the blown grass clippings meeting resistance to discharge thereof into the catcher. OMPI

Inventors: KAESGEN HANS-HARTMUT, KAESGEN, HANS-HARTMUT
Applicants: MTD PRODUCTS INC, MTD PRODUCTS INC.
Application year: 1983
Main classification: A01D53
IPC codes: A01D34