US2253924A - Lawn mower - Google Patents

Description

E. H. WORTHINGTON when Aug. 26, 1941.

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E; H. woRTHlNGToN LAWN lIOWER Filed July 23, 1940 2 Shets-Sheet 2 lill!! .lllllflflfl ,ll/l

IEEE -aNvENTR "Mw Il www/wmv 2 0mg/MM ATTORNEY Patented Aug. v 26, 1941 UNITED STATES PATIENT ,OFFICE LAWN Mom sama n. worsmngson. nmem, N. J. Application Jui', za, 1940. seran No. 34am' 1s calm. (c1. ss-zss) The present invention relates to lawnmowers and, in particular, with bed knife supporting means permitting the use of a bed knife of a-de sirable type and form not practically usable in a lawnmower having the usualbed knife supporting means.. I

The rotating y knife of a lawnmower of the abovev mentionedtype, customarily comprises a ily knife including a plurality of helical cutting blades, each of which should engage and press against the bed knife during each revolution of the y knife, at a contact point which moves progressively from one endv of the cutting edge to the other, and ordinarily the bed knife lis thus engaged at all times at a plurality of points along its length, by a corresponding plurality of fly knife cutting blades. Advantageously, the4 ily knife should bear against the bed knife at all times with a substantial pressure. That pressure which ordinarily should increase with the size of the lawnmower, may vary through a considerable range, but usually may well be of the order of ve `pounds per foot of `bed knife length.

Heretofore it has been customary to Journal the rotating fly knife in a framework connecting front and rear ground engaging wheels or other elements and thereby maintained in definite relation to the ground level, to secure the bed knife to a bed knife backing plate or support mounted in the same framework, with provisions for ad:- Justment of the backing plate, and thereby of the bed knife, .tol compensate for cutting edge wear and to maintain the bed knife cutting edge in suitable parallelism with'the axis ofv ily knife rotation'.

In the preferred form of the present inventionA the bed knife .issupported on a backing orV supporting member which forms a rigid, non-adjustable element of the framework connecting the front and rear ground engagingl elements: and the fly knife is Journalled in. a separate frame of the ily knife toward and laway from a normal operatingposition in which the fly knife blades I engages and bears against the bed knife: and said framework and frame are connectedby antichattering or cutter contact regulating means, which permits the ily knife to move toward the bed knife 'as required to compensate for cutter wear whilel positively opposing movements of the fly knife away from the bed knife. 1

By mounting the fLv knife in a supporting frame separate from and movlable relative to the framework in which the bed knife backing member is incorporated as described, I obtain certain practically important structural and operative advantages, not obtainable with prior lawnmowvers in which the bed knife backing or supporting member is adjustably mounted in lthe framework in which thefly knife is journalled.

' In particular, the invention permits of the conthe bed knife backing part forming a rigid, nonadjustable' portion ofthe lawnmower framework, the tendency, inherent in .prior arrangements to movement of the bed knife cutting edge out of parallelism with the ily knife axis as a result of the bending or relative movements of diil'erent portions of the framework, may eliminated.

Furthermore, the bed knife supporting means may be shaped and disposed to accommodate a bedknife of simple cross section, appropriate for use when the bed knife is formed of some known be practically hard alloy material specially suitable for the purpose, but so tough and brittle that it is diflicult or impossible to subject it to drilling, punching and other machine operations. to which bed knives arecustomarily subjected in adapting them for use with the supporting means heretofore used.

'-Ihe'present invention is adapted for use in teriae my invention are pointed-out with partie-- mounted in said framework for bodily movement 55' uitrit! in the claims tojand forming a standing of the invention, however, its advantages, and specific objects attainedwith its use.'

reference should be had to the accompanying drawings and descriptive matter in which I have illustrated and described. a preferred embodiment of the invention.

Of the drawings:

Fig. 1 is a plan view of a lawnmower;

Fig. 2 is an elevation in ysection on the line 2--2 of Fig. l;

Fig. 3 is an elevation in section on the line 3 3 of Fig. 1 through one of the contact regulators; and

Figs. 4, 5, and 6 are elevations taken similarly to Fig. 3 and each illustrating a different modification of the regulator shown in Fig. 3.

In Figs. 1-3 of the drawings, I have illustrated the use of the invention in a so-called high wheel, hand operated lawnmower, comprising a ily knife supporting frame formed by gear case members latter extend through the horizontal body por- A, and a main tie member B rigidly connected'A at its ends to the gear case members A and in front of the revolving cutter or fly-knife C. The latter comprises a plurality of helical cutter blades C', blade supporting rings C, and a shaft C3 which has its ends joumalled in the gear case members A to turn about an axis parallel to the member B. The two driving wheels D of the lawnmower are located at the outer sides of, and are journalled in, the corresponding gear case members A. As shown, the tie bar B is displaced upwardly and forwardly from the coml mon axis of the members A and wheels D, but in larger machines in which the 'fly knife is displaced from said axis, the tie bar B may beI coaxial with and form an axle for the wheels D. 'I'hrough gearing within the gear cases A, the rotation of the wheels D rotates the ily knife C at a suitably velocity. In respect to itsv above mentioned features, the lawnmower'may be of any usual known type and form, and is shown as of the particular type and form disclosed in my prior Patent 2,049,883, granted August 4, 1936. e

The bed knife E which cooperates with the ily knife C. is supported in a framework shown as comprising side frame members F which have their forward ends pivoted on axle portions A' of the members A coaxial with the wheels D, and at their rear ends supported by a trailing ground roll H journalled in vertically adjustable bearing members G, carried by the members F.

In the preferred construction shown, the inembers F are rigidly connected by a bed knife support o r backing member I, in the form of a flanged steel bar welded at its ends to the members F, and comprising a substantially horizontal body flange and an uprising vertical flange I'l at the rear edge of the body flange. The bed knife E is shown as in the form of a flat bar with an uprising cutting edge rib E' at its front edge.

Advantageously, and as shown, the forward edge of the backing member body extends into the position'in which it is beneath and directly supports the cutting edge portion of the knife E. The framework comprising the side frame members F and the bed knife support I, thus connects, and is supported by front ground engaging roller elements formed, as shown, by the driving wheels D, and a rear ground engaging -roller element, shown 'as formed by the roll H.

- The flat barlike body of the knife E, issecured to the member I by clamping means which comprise a clamping member J and bolts K. The

tion of the member I, and through the horizontal body portion of the clamping member J. 'I'he member J is a flanged bar having an uprising rear flange J' abutting against, and advantageously welded to, the uprising flange I' of the member I. The horizontal portions of the members I and J are spaced apart to form a bed knife receiving slot in front of the bolts K. The latter, when tightened. bend the bodyl ofthe member J into clamping engagement with bed knife. The welding together of the members I and J adds to the stiness of the bed plate supporting frame, and does not interfere with the insertion or removal of the bed knife, after the clamping bolts are loosened and the fly knife is raised from its normal position in -which its cutting edges bear against the top edge of the bed knife rib E. The displacement of each enti of the bed knife E from the flange I', is fixed .by a corresponding adjusting screw KA mounted in the support I.

`The gear case members A and their tie connection B, form a rigid fly knife supporting frame which is angularly adjustable vrelative to the bed knife supporting frame, about the common axis of the axles A' and wheels D. Tobpermit such adjustment the side frames F are formed with large central openings F through which the ily knife shaft C3 extends. With theily knife shaft C3 well to the re'ar of said axis, as shown in the drawings, the weight of the ily knife C gives the latter and its supporting frame a desirable bias for angular movement in the direction to bring the fly knife cutting blades C' into engagement with the bed knife E, with the desired contact pressure. In operation, however, unevenness in the ground over which the lawnmover moves, and

variations in the cutting stresses, tend to cause.

' acting between the bed knife and ily knife supporting frames, and tending to prevent movement of the fly knife away from the bed knife.

As collectively shown in Figs. 1, 2 and 3, the means regulating the bed and fly knife contact relation, comprise two similar regulators L, one at each side of the lawnmower, and each connecting the adjacent frame member F to the adjacent gear case A. As shown in Fig. 3, each regulator L comprises a rod M having an eye M' at its lower end which surrounds a stud M2 carried by the corresponding gear case member A, to which the rod M is thus pivotally connected. The rod M extends axially through the hollow cylinder L' which constitutes the body member of the regulator L, and which has rigidly connected to it a trunnion-like part l..2 which extends through the adjacent bed knife supporting frame member F and is held in place by a nut or collarL3 secured to the part L by a set screw. The cylinder body L' of each regu- `of the parts in the opposite direction.

The clutch provisions shown in Fig. 3, are of the ball clutch type, comprising three balls N spaced about, and in engagement with the rod M, and also in engagement with the -conical inner surface O? of a hollow piston-like part O,

within the cylinder L' and surrounding the rod M. and normally engaging the lower end L* of the cylinder, As' shown, the balls N are held in spaced .relation with one another by means of a tubular cage or guide` member P through which the member lili loosely extends,v and which comprises an annular head or body portion formed' with ball receiving spaces P' and an elongated sleeve or hub portion Fa which extendsthrough an opening in the cylinder bottom wall L4.' A .spring Q actingbetween the wall L4 and the portion of the member vP, biases the latter for movement in the direction in which the balls M iam between the surface o' and the rod M, and thereby hold the latter against axial movement relative to 'said surface.

As shown in Fig. 3, the member is normally but yieldingly held against -the end wall L* of the cylinder L' by a spring R acting between the part O and a member S threaded into the upper end of the'body part L. The member S thus forms an adjustable abutment for the upper end of the spring R. By axial adjustment of the member S the tension of the spring R may be varied through a suitable operating range' having a minimum value greater than the tension of the spring Q. The spring R thus nor= mally holds the part O in fixed axial relation with the cylinder L', and thereby normally prevents movement of the y knife away from the imite, butdo not prevent movement of the y knife away from the bed knife on the development oi' an abnormal force tending to' separate the two knives.y That abnormal force may result from a shock or jolt forcing the ny knife mi the bed knife, so as tov create a knife engaging pressure sumciently greater than the normal pressure to lock the 'blades together, with the ible result of stripping gears, or otherwise injuring the lawnmower, but for the ally connected to the side 'frames F throughA pivots formed by the parts L? and L.

Where the automatic safety release function of the spring R shown in Fis. Zi is not required, I may make use of a simpel' iorrn of contact regulator such as thaty shown in Fig. 4, fromv which the spring R and abutment member S of Fig. 3 are omitted. and in which the member O of Fig. 3 is replaced by a member 0A threaded into the upper end of the body cylinder member L'.

The general anti-chattering clutch action ob` talnable with the constructions shown in Figs. 3 and ft, can vbe obtained with very different mechanisms. For example, it can begobtained with sucha hydraulic clutch or dashpot mechanism as isshown in Fig-5. The mechanism shown in Fig. 5 comprises a cylinder LB, which may be connected to the bed knife supporting framework, as the cylinder 'L' of Figs. 1 3 is connected to the framework in which the bedknife is mounted. Aopiston M5 working in the cylinder LB is connected to one end of a piston stem MB 'which may be connected at its other end f to a gear housing .A as is the rod M of Figs. 1-3.

safety action of the spring R, which then yields to permit the elevation of the ily knife. e spring R also serves as e. relief device when sonrie object caught between the blades, is too strong to be out or broken by the blade action, and thus subjects the two knives to an abnol separating force.

Advaneously, means are provided for manually rendering each contact regulator inoperative to oppose movement of the ily knife away from the bed ie. Thus, as shown, by manual adjustment of a release lever T, the ball guide member P may be manually depressed, against the action oi the spring Q, to release the normal clutch connection between the parts M and O. The release iever T is bifurcated at one end, and has its :bifurcations pivotally connected through trunnion pivots T', to the lower end of the sleeve portion P'of the member P. The handle T has two engaging surfaces ".lz and T3 inclined at an angle to one another.

In the normal angular position of the handle T, shown'in full lines in Fig. 3, the surface T bears against the lower end of the member L andthe ball'member P ls then held in its normal operative position by the spring Q, with the to the lower end of the cylinder LB. Such flow y balls N wedged-between the rod M and surface vdisplaced downwardly from its normal position,

so that vthe balls N no longer exertkth'eir normal clutching action between the parts' M and O. With the release'lever 'I'` in its dotted line D081- I The piston M5 is formed with ports Ms for the passage of a glycerin mixture or other suitable dashpotfluid from the lower end to the upper -end of the space in the cylinder shell LB. A nexible washer or valve M secured against the upper side of the piston is adapted to close the ports M@ against how downward therethrough. The piston Mii with its ports M' and the valve Ml, thus cooperate to permit free down movement oi' the stem am and hence'of the ily knife, while automatically opposing chattering up movements of the piston and y knife.

. En the regulator shown in Fig. 5, the portions of the cylinder space above and below the piston .are normally nlled with the dashpot liquid, and the sort of automatic' relief action obtained by the use of the spring R. and movable part O of Fig. ii,v may be obtained with the arrangement shown in Fig..5, by the provision of a by-pass connection L. between the upper and lower ends of the cylinder space, which is normally closed by a valve L10. The valve L10 is biased to its closed position' by'a spring L11. The tension of the spring can be varied by the angular adjustlment of a threaded cap member La closing thek outer end of a spring chamber L, and determines the liquid pressure in the upper end of the cylinder LB required to force the valve L*o away from its seat, and thereby permit liquid flow through the by-pass from the 'upper end permits an up movement of the piston M5, and thereby of the fly knife supporting frame. to which the upper end of the piston stem connected.

In'the regulator shown in- Fig. 6, manually controlled means are employed to releasably. lock the fly knife in the position in which its blades bear with suitable pressure against the bed knife. Said means comprises a clutch mechanism mounted within a cylinder LC which may be exactly like the cylinder L' first described, except that it is formed with anv opening L10 at one side through which clutch parts W' extend. yEach clutch part W' has its end Within the cylin-der LC pivotallyconnected to the base or body portion of a yoke shaped clutch member W which has its parallel arms W2 formed with apertures large enough for the free' movement therethrough of the rod M, when the members W' are moved toward one another into their positions shown in dotted lines in Fig. 6.

Normally, the members W' are spread apart as shown in full lines in Fig. 6 by a spring W3. When so spread apart, each member W' is in gripping relation with the rod M, and the members W' then prevent movement of the rod M in either direction so long as the yoke member W is held against one end of the cylinder LC by the spring RC as shown in Fig. 6. The spring RC serves the same release purpose shown by the spring R shown in Fig. 3. As shown, the spring RC acts against an abutment member SA threaded in an opening in the end oi the cylinder LC.

As shown, the normal position of the uppermost of the two'members W shown in Fig. 6 is fixed by an adjustable stop X threaded through a bracket member X secured to the cylinder LC. A spring Y is shown as acting between the member LC and an abutment shoulder M10 carried by the member M adjacent its eye M.

While in accordance with the provisions of the statutes, I have illustrated and described the best forms of embodiment of my invention now e known to me, it will be apparent to those skilled in the art that changes may be made in the form of the apparatus disclosed without departing from the spirit of myinvention as set forth 4. A lawnmower as specified in claim l, in which the said means comprises a connection between said frame and framework including a clutch interposed between said frame and framework permitting their relative movements in the directlonto move the fly knife toward said bed knife and tending to prevent their relative movements in the-opposite direction. and also including means yielding to permit such relative movement in' the opposite direction when subjected to an abnormal force.

5. A lawnmower as specified in claim 1, in which the said means comprises a part connected to said frame, a part connected to said framework, clutch means permitting relative movements of said parts in one direction and opposing relative movement of said parts in the opposite direction.

6. A lawnmower .as specified in claim 1 in which the said means comprises a part, a connection between said part and said frame, a second e part, a connection between said second part and one direction.

in the appended claims and that in some cases certain features of my invention may be used to advantage without a corresponding use of other features.

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. A lawnmower comprising in combination front `and rear ground engaging roller elements, a framework connecting said elements and com- 'prising side frame members `and a bedknife support extending between and having its ends rigidly connected to and in fixed relation with said side frame members, a bed knife rigidly mounted on said support, a revoluble fly knife normally above and engaging said bed knife, a frame in which said flyknife is journalled and which .is pivotally connected to said framework to turn said fly knife toward and away from said bed knife, and means operatively connecting said framework and frame and normally operative to maintain the fly knife inengagement with the bed knife.

2. A lawnmower as specified in claim '1, in which the said means comprises a' clutch interposed between said frame and framework per-v mitting their relative movements ln the direction to move the fly knife toward said bed knife and tending to prevent their relative movements 7. A lawnmower as specified in claim 1 in which the said means comprises a part pivotally connected to said framework, a part pivotally connected to said frame, one of said parts including a rod-like portion and the other of said parts being formed with a conical chamber in which said rod is 'axially disposed and clutch balls tending to wedge between the periphery of said rod and the wall of said cavity and thereby prevent relative movement of said parts in one direction.

8. A lawnmower as specified in claim 1 in which the said means comprises va part pivotally connected to said framework, a part pivotally connected to said frame. one of said parts including a rod-like portion and the other of said parts being formed with 'a conical chamber in which said rod is axially disposed, clutch balls, and resilient means tending to wedge said balls between the periphery of said rod and the wall of said cavity and thereby prevent relative movement of said parts in one direction.

9. A lawnmower as specified in claim l Ain lwhich the said means comprises a part pivotally connected to said frame, a part pivotally connected to said framework. and one of said parts including a rod-like portion and the other of said parts being formed with a conicalV chamber in which said rod is axially disposed and clutch balls tending to wedge between the periphery of said rod and the wall of said parts in one direction, and means manually operable to retract said balls and thereby permit relative movements of said parte in either direction.

10. A lawnmower comprising in combination front and rear ground engaging roller elements. a frame work connecting said elements and including side frame members and a horizontally disposed bed knife supporting member rigidly connected to said side frame members. a bed knife rigidly mounted on said supporting member, a revolvable ily knife normally above and engaging said bed knife, and ily knife supporting means movable relative to said framework to move said fly knife toward said bed knife as required to compensate for knife wear.

2,253,924 V 11.` A `iawnmower as specified in claim 10, in

which the bed knife supporting member extends beneath and directly supports the bedknife adjacent the cuttingvedge of the latter.

12. A lawnmower as specified in claim 10, `in which the bed knife supporting member has a bed vknife supporting beneath and directly supporting the bed knife along substantially the flange of the other and each with a substantially horizontal flange spaced from the horizontal flange of the other to form a horizontal slot or kerf into which the bed'knife extends.

15. A lawnmower comprising in combination front and rear ground engaging roller elements, a framework connectingsaid elements and comprising side frame members and a bar-like member having itsends welded to said side frame members and having a substantially horizontal bed knife supporting surface, a bed knife on and clamped against said surface, a revolvable ily knife normally above and engaging said bed knife, fly knifesupporting means -movable relative to said frame work to move said fly knife toward and away from said bed knife, and means:

normally operative to maintain said fly knife inengagement with the bed knife.

. v EDWARD H. WORTHINGTON.

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