US2204255A - Lawn mower - Google Patents

Description

June 11, 1940.

A. F. MoYER 2,204,255

LAWN MOWER Filed Jan. 2'?, 193e 2' sheets-sheet 1 WLM fawn:

June 11, 1940. A. F. MOYER LAWN MOWER fnl/@afar ,4A/fos F. Mo Yee 'Ml-l j im 2 Sheets-Sheet 2 Filed Jan. 27, 1938 A TToB/vs Y@ Patented June 11, 1940 LAWN PATENT OFFICE MOW ER Amos F. Moyer, Minneapolis, Minn., assigner to Toro Manufacturing Corporation of Minnesota,

Minneapolis, Minn., a corporation of Minnesota Application January 27, 1938, Serial No. 187,194

8 Claims.

This invention pertains to lawn mowers `of the type having a plurality of helical knives in the form of a cutting reel, which is revolvedlin cooperative relation with a stationary knife herein called a bed knife. Such cutting reels are accurately ground and sharpened so that when they are revolved, the cutting edges travel in a cylinimportant factor in the cutting vability of lthe,

mower, the maintenance of sharpness .of the cutting knives and the bedkn'ife, and in the ease of operation of the mower. Improper adjustment often quickly dulls and destroys the required accurate shape of the cutting edge and even damages the internal grain structure of themetal in the knives to such an extent that they. can again be made serviceable only with difficulty.

It is therefore a general object of theinvention to providea bed knife adjusting means of simplied` construction that is easy to manipulate and sensitive in the attainable precision ofadjustment, and which is capable of being positively locked or retained in adjusted position with the `least possibility that the act of locking the same shall alter the adjustment.

In many types of bed knife adjustments presently used, separate screw members are employed, one to urge the bed knife toward the reel and another to urge it away. Eachscrew'when tightened places the intervening members under strain and serves to lock or retain the adjustment against slipping. The final position of the bed knife is uncertain due to the elasticity of the parts, the slack between various members, and the fact that the effect of theadjustment depends both upon which of the adjusting screws J is tightened last, and the degree of tightness with which it is tightened. Considerable mechanical skill is, therefore, necessary in order to obtain a satisfactory adjustment with such a mechanism, and the average operator frequently does more harm than good when an attempt is made to adjust the bed knife.

It is accordingly a further object to provide a simplified bed knife adjustment means in which a single adjustment member provides the adjustment of the knife both towardv and from the bar, and in which means are provided for effectively locking such member after adjustment. More specifically, it is an object to provide such an arrangement in which means are provided for applying pressure to the adjustment member when in adjusted position, and for releasing the pressure during readjustment.

It is a specic object of the invention to provide a mowing machine bed bar adjustment in which a pivotally mounted bed bar is held in cutting relationship with a cutting reel by` means of an adjustment screw connectingthe bed bar and the machine frame, which screw is held against longitudinal movement and locked against rotary adjustment movement by an integral flange which "is held between a suitable locking member and a part of the frame, the pivotal axis beingA parallel with the cutting edge of the `bed knife, and generally disposed rearwardly thereof.

It is another object of the invention to provide a hand operated clamping device for the bed bar adjustment member of a vmowing machine. f

Other objects and features of the invention are those inherent and suggested by the drawings, and those inherent and suggested by the embodiments of the invention described hereinafter, all of which are features of the invention.

In the description hereinafter given, reference is had to the accompanying drawings in which like characters represent corresponding partsin all views.

Figure 1 is a side elevation of the lawn mower showing the' bed knife adjustment device of the present invention; Y

FigureA 2 is a fragmentary section along the lines 2-2 of Figure 1;

Figure 3 is a bottom View of the parts shown in Figure 2;

Figure 4 is a fragmentary enlargement partly in section of the adjusting mechanism showny in Figure l; i

Figure 5 is a side elevation of a modification of the invention;

Figure 6 isa fragmentary view along the line 5 6 of the modification shown in Figure 5; and

Figure 7 is a fragmentary view partly in section along the line 1 1 of Figure 6.

Figure 1 shows a lawn mower of the type in which the cutting reel is propelled by drive wheels of the machine.v This construction consists of a frame comprising side plates I on which are mounted drive wheels 2. The frame is supported at its trailing edge by a wiper roll 3. Intermediate the drive wheels and the wiper roll cylindrical path so as to cooperate with the bed knife 8.

The bed knife 8 is carried by bed bar 9 which is pivotally mounted on side plates I by means of screws I0 which pass through holes in the sidel plates. The screws ID are of such a size as to fit tightly into boss II of the bed bar and also of such a size as to form a closely journaled fit with the holes in side plates I, and without being in locked engagement with plate I.

At each of the outer ends of the bed bar 9 there is formed an overhanging lug or protuloerancev I2 which is threaded so as to receive adjusting screw` I3 which is generally parallel with the side plate and passes through a relatively large opening I4 in the side plate lower flange. The upper end .of `the adjusting screw- I3 is provided with a hand wheel I5`by which it may be turned. At an intermediate part of the adjusting screw I3 an integrally formed collar I6 is provided as shown in Figure 4. This collar has a spherical under surface I1 which cooperates with a loosely fitted washer I8 which has one spherical surface I9 and one plane surface 2D.

The adjusting screw I3 and spherical washer I8 are held in position by a locking arrangement comprising a forked locking plate 23 which is made of spring steel so as to be slightly flexible, and is shaped so as to have a slight bend and a central aperture 25. The forked e-nd 26 of locking plate 23 straddles the adjusting screw I3 and is held against collar I6 by the action of cam 24 which operates about pivot screw 2B threaded into the side frame I at 29. 'Ihe under surface of the cam 24 is grooved transversely, and when it is in the position shownin Figure 44, the cam groove 21 is parallel with the ridge at the bend in `spring plate 23, and thus does not compress the plate, but when the'cam is rotated ninety degrees, the cam groove 21 is` crosswise of the ridge and hence contacts with and flexes the spring plate downwardly into locking position. The unlocked position ofthe cam is shown in- Figure 4, at which time the cam surface 21.gen erally parallels'the convex upper surface 3| of the forked locking'plate. A

The upper end `of the pivot screw 2B isvprovided with a plurality of locknuts 30 which may be adjusted so as to bring the cam surface 21 of hand-operated cam 24 into engagement 'with the upper surface 3| of the forked locking'plate 23. The slight resiliency of plate 23 itself comn pensates for slight wear, and further Wear which may take place between thecam surface 21 of cam 24 and the upper surface 3I of the forked locking plate 23, and wear upon the upper surface of collar I6, may be compensated for bya slight tightening of lock nuts 30. As shown in Figure 1, cam 24 is provided with a hand grip 32 which is arranged so as to be parallel with side plate I when the cam surface 21 is in locking position so as not to catch grass and weeds which brush along the side plate I` when the mower is in operation.

The slight resiliency of plate23 also insures that the pressure applied to flange I6 for locking screw I3 will be the same save for infinitesimal wear, after successive manipulation of v cam 24 to the released position and back to en.

gaged position, and such manipulation therefore causes the knife adjustment to depend only upon the angle through which screw I3 is turned in one direction or the other before locking; whereas in other adjusting and locking devices the final adjustment of the knife depends both upon the angle through which one of the adjusting screws is turned and upon the tightness with which the other screw is locked.

The operation of the adjusting mechanism is as follows:

The hand grip 32 of the cam 24 is rotated away from the frame I to a position roughly perpendicular to the side frame I, as indicated in dot-and-dash lines in Figure 2. When in this position the cam surface 21 will relieve the tension on forked locking plate 23 and thus permit `easy rotationl of adjusting screw I3 by hand Wheel I5. The hand wheel is turned a required or assumed amount and cam 24 returned to engaged position, thereby pressing surface 21 against surface 3I of forked locking plate 23 and flexing the plate to forcibly engage forked end 2B against collar II.` Thereupon, the relationship of cutting edge 33 of bed knife 8, with respect to cutting edges 1 of spiral knives 6 on cutting reel 4 can `be checked, and determination made as to whether or not further adjustment of screw I3 by hand wheel I5 is necessary.

The required relationship of the cutting edges depends on one or more of several factors, such as the ease of operation if the mower is pushed by hand, the toughness of grass to be cut, the sharpness of the cutting edges, or the precise circular relationship of the several cutting edges on the reel. If a reel is slightly sprung, as by accidentally striking. a hard object at high speed,

it vis a simple matter by the improved sensitivity of this adjusting means, to cause the bed knife to rub lightly on that part of the spiral knives thatvmay be sprung outwardly and maintain a clearance at other places that is small enough to still Vout the grass. Operation of the mower in this condition causes the contacting portion of the spiral knives to wear away, thus restoring a circular form of cutting edges on the reel. A

further advantage in the ability to adjust the knives precisely to a very light contact is to produce thev well known self-sharpening due to natural wear.' It is not so Well known, particularly by operators, that the diflculty in manipulating other types of adjustment often causes excessive pressure between the cutting edges. This causes uneven wear and, indeed, local hardening of the metal at certain spots, due to the hammering action that takes place. In consequence, the cutting qualities of the knives are often quickly destroyed -by such accidentally produced, but faulty, adjustment. The uncertainties that heretofore have been a prolific cause of such troubles areeliminated by this improved adjustment.

It will be noted that no part of the adjustment mechanism comprising adjustment screw I3, bed bar 9, boss I2, or bed bar mounting screws IU is placed under stress when the adjustment is in locked position, since the locking force of forked end' 26 is concentrated upon collar I6 which directly overlies spherical washer I8, which is in turn in direct contact with surface 20 of the side frame I. The result is that the locking of the adjustment does not tend appreciably to change the adjustment of the bed knife 8, even if the adjustment of nuts 3l] is altered. The spherical Surface I9 of washer I8 and the spherical undersurface I 'I Aof collar I6 permit the adjustment screw I3 to "turn and move slightly to accommodate the arcuate motion of bed bar 9 about pivot point IIJ. Moreover, the cam 24 is` closely adjacent the collar IE wherebya great force is not necessary to effectively lock the adjustment and there is a minimum of elastic deformation in any parts anda freedom from strain imposed on the pivot that would alter the predetermined adjustment.

It will also be noted that the adjustment screw I3 and cam 24 may both be operated from above the mower since the hand wheel I5 and hand grip 32 are accessible from these positions.

Where the mowing machine is of narrow width, such as edging mowers, the bed bar 9 may, if desired, be made of sufficient rigidityr that only one adjusting screw I3 is necessary in order to hold the bed knife in correct cutting relationship with respect to reel 4. For greater widths an adjusting screw I3 and cam surfaces 21-3I may be provided at each end of the bed bar 9.

In the modification shown in Figures 5, 6 and 'l the cutting reel 4 is suspended from a superframe 35 by means of side plate 36, and the cutting reel 4 is driven by means of a suitable gearing from a motor device mounted above frame 35. The gearing and motor have not been shown since they do not form a part of the present invention. The bed knife 8 is mounted upon bed knife carrying bar 9 which is pivoted to side plates 36 by pivot screws Ii! as in the modification previously described. The bed knife carrying bar 9 is formed with an inner boss 3l into which adjusting screw 38 is threaded. Screw 38 passes through a relatively large opening 39 in boss 40 which is formed on the inside of side plate 36 and thus forms a suspension by which the bar is positioned. The adjusting screw 38 is provided with a fiange 4I and a slotted head 42.

The locking arrangement in this modification consists of a plate 43 which has a forked end 44 which straddles head 42 and rests against the upper surface 45 of the adjusting screw 38. The locking plate 43 is drawn downwardly against the flange 4i by means of a locking screw 46 which passes through a central aperture 4'l of the locking plate and is threaded into the boss 40 at 4B.

The operation of this modification of the invention is similar to that shown in Figures 1 through (i, except that kthe adjusting screw 38 and lock screw 46 are manipulated by means of a screw driver. The locking screw 46 is ordinarily screwed down until the forked end 44 rests tightly against the upper surface 45 of flange 4I on the adjusting screw 33. When a change inadjustment of bed knife 8 is desired the locking screw 46 is loosened slightly so as to relieve the pressure between forked end 44 and upper surface 45 of the flange, at which time the screw 38 may be turned so as to bring the cutting edge 33 of the bed knife into proper relationship with respect engagement is sufficient to prevent rotation of the screw. The effect of the adjustment made upon the relationship between the knives is then observed.

It will be noted that in this modification also,

any variation in the pressure of the locking plate 44 upon flange 4I does not stress that portion of Vscrew 38 which is between the boss 40 of the side plate 36 and boss 31 on bed knife carrying bar 9. Thus the tightening of the lock screw 4B to one degree or another does not appreciably tend to change the effect of the adjustment which has been made of the adjusting screw. This is important since it permits adjustments to be made with intelligence that is unhampered by obscure mechanical or human factors, and permits an inexperienced operator to readily learn the proper adjustment for his mower.

It is obvious that many changes in details may be made without departing from the spirit of the invention described, and herein claimed. For example, similar principles might be applied-for adjustment of movable reel bearings with respect to a stationary bed knife, etc.

I claim as my invention:

1. A bed knife adjustment for a lawn mower having a frame, a cutting reel rotatably mounted on said frame, and a bed knife mounted on said frame for movement into a position for cooperation with said cutting reel, comprising a flanged adjustment screw connecting said bed knife and frame for adjustably positioning said knife with respect to said frame, and clamping means positioned to bear upon said flange.

2. A bed knife adjustment for a lawn mower having a frame having a positioning surface thereon, a cutting reel rotatably mounted with respect to said frame, and a bed knife mounted on said frame for movement into a position for cooperation with said cutting reel, comprising a flanged adjustment screw threaded into said cutting knife and positioned so as to have said flange adjacent said surface, and means for applying pressure as desired to said ange so as to force it into tight contact with said surface.

3. A bed knife adjustment for a lawn mower having a frame having a protuberance thereon, a cutting reel rotatably mounted with respect to said frame, and a bed knife mounted on said frame for movement into a position for cooperation with said cutting reel, comprising a flanged adjustment screw threaded into said cutting knife and positioned so as to have said flange adjacent said frame protuberance, and a fork positioned on said frame so as to engage said flange.

4. A bed knife adjustment for a lawn mower having a frame having a protuberance thereon, a cutting reel rotatably mounted with respect to said frame, and abed knife mounted on said frame for movement into a position for cooperation with said cutting reel, comprising a flanged adjustment screw threaded into said bed knife and positioned so as to have said fiange adjacent said frame protuberance, a fork positioned on said frame so as to engage said flange, and rotary means for forcing said fork into ange engaging relationship.

5. A bed knife adjustment for a lawn mower having a frame, a cutting reel rotatably mounted on said frame, and a bed knife mounted on said frame for movement into a position for cooperation with said cutting reel, comprising an adjustment screw shaft having a screw threaded portion and a circumferential shoulder portion, said screw shaft directly connecting the bed knife and frame with said screw threaded portion threaded into one of them and having said circumferential shoulder portion in abutment with the other of them, and positive stop means pressing on the screw shaft to hold the shoulder portion thus in abutment.

6. A bed knife adjustment for a lawn mower having a frame, a cutting reel rotatably mounted positive stop means pressing on the flange portion to hold the ange portion thus in abutment. '7. The combination set forth in claim 5 wherein the shoulder portion is a spherical surface.

8. The combination set forth in claim 5 Wherein the means for pressing on the screw shaft is manually actuatable;

- AMOS F. MOYER.

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