US2780034A

US2780034A - Lawnmower sharpener

Info

Publication number: US2780034A
Application number: US436576A
Authority: US
Inventors: Charles L Turner
Original assignee: MARJORY C TURNER
Current assignee: MARJORY C TURNER
Priority date: 1954-06-14
Filing date: 1954-06-14
Publication date: 1957-02-05
Anticipated expiration: 1974-02-05

Description

5 Sheets-Sheet 2 Filed June 14, 1954 II I T lllllllflill /NVE NTOR. CH9 rues L. Tue/v0? BY HAS HTTOPNEYG. HflRRIS, Mic/4, FOSTER & HHRR/S to either raise or lower the side 2,780,034 Patented Feb. 5, 1957 LAWNMOWER SHARPENER Charles L. Turner, Pocatello, Idaho,

assignor of one-half to Marjory C. Turner,

Lawnmowers of the type illustrated and described herein are very common, millions of them being in use in the United States. These lawnmowers consist of two wheels between which there is mounted a reel which is geared to these wheels and rotated thereby. Mounted uponthe reel are a plurality of curved reel knives, each of which is designed to contact a bed knife mounted between the two wheels in such a manner as to cut grass. The knives of such lawnmowers become dull in use and must periodically be sharpened. Such sharpening is preferably done by means of a grinding wheel which sharpens the blades of a lawnmower mounted in a lawnmower sharpener. It is an object of the present invention to provide an improved form of a lawnmower sharpener which is designed to be used in sharpening the reel knives of a lawnmower.

My invention may be briefly summarized as embodying a frame and novel means for supporting a lawnmower in said frame so that a power-driven grinding wheel may be accurately applied to the reel knives of the mower. More specifically, my invention is defined by the claims forming a part of the following specification. Further details of the invention will be apparent from the remainder of this specification and the accompanying drawings, in which:

Fig. l is an isometric view of a lawnmower sharpener of the present invention;

Fig. 2 is a partially cross-sectional view taken generally along line 22 of Fig. 1;

Fig. 3 is a partial top view taken in the direction of the arrow 3 in Fig. 1;

Fig. 4 is a partially sectional view taken at line 4-4 of Fig. 3;

Fig. 5 is a of Fig. 2;

Fig. 6 is an enlarged view showing guide means employed with the invention, this view being taken inthe direction of the arrow 6 in Fig. 5; and

Fig. 7 is a partially sectional view taken along the line 7--7 of Fig. 5.

In Fig. 1 there is shown partially sectional view taken at line 5-5 a lawnmower sharpener 10 including a machine frame 11 serving as a base for the sharpener. This machine frame 11 consists of

legs

12, 14, 15 and 16, crossbraces 17, top supports 18, and a generally flat top section 19.

Mounted upon the machine frame 11 is what is gen erally designated a roller support frame 21. This latter frame is secured to the machine frame 11 by means of bolts 22 attaching side braces 23 of the roller support frame 21 to angle members 24 fastened to the top 19. These side braces 23 each carry threaded bearings 25 through which there project threaded cranks 26 having lower support surfaces 27 which are adapted to bear against the top 19 of the machine frame 11. As will be readily apparent, these cranks 26 may be rotated so as braces 23 about the bolts 22. Each of the side braces 23 also has an upstanding end support 23 mounted on the end 29 of the side braces 23 remote from the bolt 22. These upstanding end supports 28 are provided with several generally aligned V- shaped supports 30 which are adapted to hold an angle iron brace 31 in an inverted position with the apex 31 or" this angle iron brace in a generally downward position, as indicated in Fig. 2 of the drawings. This angle brace 31 is adapted to carry support braces 32 consisting of a lower member 33 fitting within the angle brace 31, and upstanding members 34 having upper V-shaped notches 35 which are adapted to hold the roller of a lawnmower above the angle brace 31 when the size of the lawnmower makes this desirable. The support braces 32 also carry clamping flanges 36 attached to the lower member 33. The clamping flanges 36 each carry a threaded bearing 37 and a threaded crank 38 which is adapted to be rotated within the bearing 37 so as to hold the support brace 32 at any desired location along the angle brace 31. Preferably, these support braces 32 are positioned substantially as shown in Figs. 1 and 2 of the drawings so as to hold the ends 41 of a roller 42 attached to a lawnmower 43.

The lawnmower 43 includes wheels 44, a reel 45 mounted upon a shaft 46 extending between the wheels 44, a bed knife 47 carried upon an appropriate conventional carrying member 48 secured between the two wheels 44, and a top tie rod 49. The reel 45 includes hubs 59 carrying reel knives 51 (Fig. 2.). The roller 42 is connected to the rest of the mower 43 by means of supporting arms 52.

The lawnmower 43 is held in position with the roller 42 in the location indicated by means of a balancing assembly 56 which includes a pipe 57 rotatably held within U-shaped brackets 58 mounted upon the legs 12 and 14- of the machine frame 11. jacent its center an extended rod 59 to which there is secured a second rod 60 by means of a bearing assembly 61 including cranks 62 designed to secure the rods 59 and 60 to one another. The rod 60 is attached to at least one Z-shaped bracket 63 (Fig. 2) containing a bottom wall 64 attached to the rod 60, an upstanding wall 65 projecting generally parallel to the rod 60, and a top wall 66 which is substantially perpendicular to the wall 65 and parallel to the wall 64. The Z-shaped bracket 63 is adapted to be positioned over the tie rod 49 of the lawnmower 43 substantially as shown with the rods 59 and 60 being adjusted as necessary.

As illustrated in Fig. 2 of the drawings, when the balancing assembly 56 is used for the purpose described, the tie rod 49 of the lawnmower 43 is held between the

walls

64 and 65 of the Z-shaped bracket 63. If desired, the tie rod could be held between the

walls

66 and 65 of this same bracket by rotating the rod 60. The precise shape of the bracket 63 is designed so that either side of this bracket can be utilized for holding the tie rod 49. In order to prevent movement of the lawnmower 43 during operation of the lawnmower sharpener 10, a link 67 is attached to the rod 60 adjacent the Z-shaped bracket 63, and this link in turn is connected to a spring 68 which is fastened to the cross braces 17 as indicated in Fig. 1 of the drawings. In effect, the arrangement created in the balancing assembly 56 is one in which the lawnmower 43 is held in what may be termed an overcenter locked position in which rotation of the lawnmower 43 towards the pipe 57 is prevented because of the fixed position of the rod 60.

Immediately above the lawnmower 43 there is placed a grinder support frame 71 including upstanding supports 72 mounted upon the top supports 18 by means of bolts 73 so as to be rotatable about these bolts with respect to the machine frame 11. Each of the supports 72 is provided with a crank bracket 74 carrying a threaded crank 75, one end of which is secured rotatably within a bushing 76. The bushings 76 are mounted upon the

legs

12 and 14 as indicated in Fig. l of the drawings.

The pipe 57 carries ad- By virtue of this construction, it is possible to adjust the location of the supports 72 as desired.

The ends '77 of these supports 72 are formed in the shape of curved notches which are intended to carry 'cylindricalend,sections 78 (Figs. 3 and 4) of a cylindrical' support 79 projecting between the supports 72 above the lawnmower 43 and the other items previously described. As is apparent from Figs. 3 and 4 of the drawings, the support 79 includes end flanges serving to retain the end sections 78 within the ends 77. As shown in the drawings, these end sections 715 are preferably of smaller diameter than the support 79. The cylindrical support 79 is rotatable in the curved notches in the' ends 77 of the supports 72. This permits the support'79 to be rotated during the lifetime of the machine, thereby distributing the wear on the support around its entire circumference.

The support 79 is adapted to carry a grinder assembly 85 including rollers 86 carried by a frame 87 projecting generally'below the support 79. This frame 87 holds an attached electric motor 88, a motor control switch 89, a grinding wheel 90, and a grinding guide 91. As is apparent from Figs. 1 and 2 of the drawings, a belt 92 mounted on pulleys 93 attached to the motor 88 and the grinding wheel 90 is used to rotate this grinding wheel. As best seen in Figs. 2, and 7, a guide frame 94' is secured to the frame 37 so as to be positioned on the side of the grinding wheel 90 remote from the frame 87. This frame 94 includes a slot 95 and parallel guide ridges 96. In use a guide 97 having a flat side 98 is held in position between these ridges against the frame 94 by means of a bolt 99 projecting through the slot 95. The guide 97 includes a curved bottom 101 leading to a projecting tongue 102. This tongue 102 is adapted to be adjusted soar; to bear against a reel knife 51 when using the. sharpener 10.

A bushing 105 forming, together with the various attached members. indicated below, the grinding guide 91, is secured to the frame 87 below the grinding wheel 90; this bushing is provided with an opening 106 carrying a threadedshaft 107, the end of which adjacent to the lawnmower 43 is provided with a hook follower 108 and the other end of which is provided with a handle 109. The shaft 107 is provided with a flat face 110 against which a block 111 is normally held during operation of the device by means'of a leaf spring 112, as is apparent from Fig. 6 of the drawings. This leaf spring is secured to the bushing 105 and to the block 111 by means of screws 114. The shaft 107 carries a threaded follower'115 positioned on the side of the bushing 105 remote from the block 111. This follower 115 includes a handle 116, a depressed center portion 117, and a flange 118 which is located immediately adjacent to the bushing 105. A hook 119 secured to the bushing 105 engages this flange 118, preventing movement of the follower 115 away from the bushing as this follower 115 is turned. Unintentional rotation of the follower 115 is prevented by means of a spring 120 which is attached to the bushing by screws 114 so as to bear against the flange 118.

The operation of the lawnmower sharpening machine is essentially very simple. In using this device, the lawnmower 43 is moved into position by means of a hoist 125 of essentially conventional design mounted on an upward extension 126 of the leg 14. The various component parts of the machine 10 are adjusted substantially as illustrated in the drawings in order to receive this lawnmower, and to hold it so that the grinding wheel 90 and the grinding guide 91 are immediately adjacent the reel 45 and the bed knife 47. positions of these parts, adjustment of the various cranks, etc. is, of course, necessary.

After the mower has been located in this manner, the grinder assembly 85 is moved upon the support 79 to adacent a stop 127, and the switch 89is actuated, turn- In order to obtain the ing on the motor 83 causing the grinding wheel 90 to rotate. The grinding assembly 8d is manually moved from adjacent the adjustable stop 127 to adjacent another adjustable stop 128. The grinder assembly is pulled across the reel knives of the mower 43 by a cord 130 which is attached to the frame 87 and runs over a pulley 131, a weight 129 providing a tension force in the cord 13%). The force applied to the frame 8'7 by the cord 130 may be adjusted by varying the weight 129 so that the grinding of the reel knives 51 proceeds at a pace corresponding to the amount of grinding needed for these knives.

The support member 79 is adjusted with respect to the reel knives 51 so that theforce of gravity acting on the grinder assembly tends to move the grinder assembly away from the reel knives. The guide assembly 91 maintains the grinder wheel 91} in the desired position by means of the hook end 108 which rides on the top surface of the bed knife 47. By this arrangement, the clearance between the bed knife and the ground reel knife is maintained constant regardless of the variations in the contour of the bed knife. The relationship of the cylindrical support member 79 and the reel knives 51 may be adjusted so that the pressure exerted by the grinder wheel on the reel knives is at an optimum value for efficient blade sharpening. It is essential that this pressure is not too great so that the cord 13% and weight 129 can traverse the grinder along the knife. The grinder wheel rotates clockwise, as seen in Fig. 2, applying a counterclockwise torque to the reel 45, causing the reel knife to rest the tongue 1492.

After a particular reel knife 51 has been ground, the handle 109 is rotated, disengaging the hook 108 from the bed knife 47, and the grinder assembly 85 is pulled away from the lawnmower 43 and brought back adjacent the stop 127 where the handle 109 is rotated, locking another reel knife 51 in contact with the grinder wheel 90 and again hooking the hook 108 over the bed knife 47. The grinder assembly 85 is brought against the stop 128 by a weight 129 pulling on a cord 130 attaching the frame 87 to the upstanding support 72. The cord 130 goes over

pulleys

131 and 132 substantially as shown. The grinding step indicated is then repeated.

Those skilled in the art will realize that the machine herein described is exceedingly efiicient for the purpose intended and may be readily manufactured with a minimum of difficulty. Because of the fact that all the moving parts with the machine are located in what may be generally termed an inaccessible position, it may be located in a crowded shop where customers are apt to come in contact with the machine while transacting business.

Those skilled in the art will realize that the herein described invention is capable of modification within the scope of the instant disclosure. Such modifications are to be considered as part of the inventive concept insofar as they are defined by the appended claims.

I claim as my invention:

1. A new and improved lawnmower sharpener, which comprises: a machine frame serving as a base for said sharpener; a roller support frame attached to said machine frame, said roller support frame being adapted to support a roller of a lawnmower; a balancing assembly attached to said machine frame for engaging part of a lawnmower and holding said lawnmower in a fixed position with respect to said roller support frame and said machine frame; a grinder support frame secured to said machine frame, said grinder support frame projecting above said roller support frame and said balancing assembly, said grinder support frame including an upper portion positionable substantially vertically above a lawnmower placed upon said roller support frame, the upper portion of said grinder support frame being movable, in an approximately horizontal path, relative to said roller support frame and said balancing assembly; a grinder assembly including a grinder Wheel and a motor and guide means for engaging a lawnmower and guiding said grinder wheel with respect to said lawnmower and said grinder support frame, said grinder assembly being movably attached to said grinder support frame, said guide means restraining said grinder assembly from swinging away from a lawnmower engaged by said guide means; and means for moving said grinder assembly with respect to a lawnmower positioned upon said roller support frame.

2. A lawnmower sharpener as defined in claim 1, wherein said grinder support frame includes a cylindrical support member located generally parallel to said roller support frame above said roller support frame and said balancing assembly a suflicient distance so as to be above a lawnmower placed upon said roller support frame, said grinder assembly being capable of moving about the axis of said cylindrical support member and along the length of said cylindrical support member, said grinder assembly being carried by said cylindrical support member.

3. In a lawnmower sharpener, the combination of: a base; a roller support mounted on said base, said roller support being movable relative to said base in a substantially vertical plane, said roller support being adapted to support a roller of a lawnmower; overcenter locking means rotatably mounted on said base, said overcenter locking means including angle means for engaging part of a lawnmower and spring means coupling said angle means to said base, said spring means urging said angle means toward said roller support when a lawnmower is positioned therebetween; a grinder support frame mounted on said base and including a support member positioned above said roller support and said overcenter locking means, said support member being movable in an approximately horizontal path relative to said roller support; and a grinder assembly movably attached to and dependent from said support member, said grinder assembly including a grinder wheel and guide means, said guide means engaging the bed knife of a lawnmower mounted on said roller support and exerting a force on said grinder assembly contra to the force of gravity thereon, said guide means force urging said grinder wheel toward the lawnmower, said approximately horizontal movement of said support member varying said guide means force.

4. A new and improved lawnmower sharpener, which comprises: a machine frame serving as a base for said sharpener; a roller support frame attached to said machine frame, said roller support frame being adapted to support a roller of a lawnmower; a balancing assembly having a support member rotatably carried by said machine frame, adjustable spacer rod means attached to said support member, angle means attached to said adjustable spacer rod means, and spring means connecting said angle means with said machine frame, said spring means normally tending to rotate said angle means toward said roller support frame so as to force a lawn mower engaged by said angle means against said roller support frame; a grinder support frame secured to said machine frame, said grinder support frame projecting above said roller support frame and said balancing assembly a sufiicient distance so as to be above a lawnmower placed upon said roller support frame, the upper portion of said grinder support frame being movable, in an approximately horizontal path, relative to said roller support frame and said balancing assembly; a grinder assembly including a grinder wheel, a motor and guide means for engaging a lawnmower and guiding said grinder wheel with respect to said lawnmower, said grinder assembly being movably attached to said grinder support frame, said guide means restraining said grinder assembly from swinging away from a lawnmower engaged by said guide means; and means for moving said grinder assembly with respect to a lawnmower positioned upon said roller support frame.

References Cited in the file of this patent UNITED STATES PATENTS 556,868 Schareman Mar. 24, 1896 963,964 Warner Apr. 26, 1910 1,043,948 Mandley Nov. 12, 1912 1,389,588 Klay Sept. 6, 1921 2,180,911 Rogers Nov. 21, 1939 2,281,055 Smith #1 Apr. 28, 1942 2,441,045 Toepfer May 4, 1948 2,456,827 Greeley Dec. 21, 1948 2,493,619 Comstock Jan. 3, 1950 2,530,479 Pater et al. Nov. 21, 1950