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Publication numberUS1355509 A
Publication typeGrant
Publication dateOct 12, 1920
Filing dateDec 8, 1919
Priority dateDec 8, 1919
Publication numberUS 1355509 A, US 1355509A, US-A-1355509, US1355509 A, US1355509A
InventorsRoss Cleland Coldwell
Original AssigneeRoss Cleland Coldwell
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Stationary knife for lawn-mowers
US 1355509 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)





T 0 all whom it may concern:

Be it known that I, CLELAND GoLDwnLL Ross, a citizen of the United States, residing at Newburgh, in the county of Orange and State of New York, have invented certain new and useful Improvements in Stationary Knives for Lawn-Mowers; and I do hereby declare the following to be a full, clear and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention consists in the novel features hereinafter described, reference being had to the accompanying drawings which illustrate one embodiment of my invention, selected by me for purposes of illustration, and the said invention is fully disclosed in the following description and claims. My invention relates particularly to the stationary knife or blade of a lawn mowing machine. These stationary knives, as ordinarily constructed, comprise a cast or malleable iron lmife bar extending transversely across the machine and carrying the stationary blade or cutter, which is usually a flat thin piece of steel secured by means of throughout its entire length with the spiral blades of the rotary cutter or wiper. This chipping, bending, or deflection of the stationary blade occurs more frequently in machines for cutting a comparatively wide swath such as high-class hand machines, horse mowers, and motor mowers. It has been proposed, for the purpose of remedying this ,difliculty to form the stationary blade of wrought metal inthe form of a channel, the angular flanges of the channel serving to stiffen the blade structure and prevent its bending, while at the same time providing twocutting edges, so. that the blade-maybe reversed with respect -to the knife bar when one of its cutting edges has become seriously worn. This. channel knife Speeification of Letters Patent. Patented 0 1 ,12 1920. Application filed. December 8, 1919. Serial no. 343,344.

tory in use, it is expensive to manufacture, and its use has been limited to a large extent, on that account, to lawn mowers of the higher grades, and more expensive types such as the higher priced hand lawn mowers, and mowers operated by horse and by motors.

The object of my invention is to provide a channel knife which will obtain the advantages -of the structure disclosed in the Coldwell patent above referred to, but which can be much more cheaply manufactured, so that the advantages of the channel knife bar can be extended to the cheaper grades oflawn mowers, and for the purpose of effecting greater economy in the usetemplated embodying my invention, and

which I have selected for the purpose of illustrating the same,

Figure 1 represents a side elevation of a hand lawn mower having my invention 1 embodied therein, a portion of one of the side frames being broken away for the purpose of showing the-knife bar and cutting blade which are illustrated in section.

Fig. 2 is a perspective view of the knife bar and cutting blade securedvthereto, de-

tached from themachine.

Fig. 3 is a transverse sectional view of the knife bar and cutting blade.

Fig. 4 is an enlarged detail section of the body portion of the blade showing the manner in which it is shaped for the reception of the cutting edge sections. v

Fig. 5 is an enlarged detail section of the completed blade.

Referring to the accompanying drawing in which I have illustrated my invention applied to a lawn mower, 1 represents the driving wheels which transmit power to the rotary cutter, indicated at 2, and provided with the usual spiral knife blade 3, the rear end of the mower being supported upon the usual adjustable ground roller 4, and the mower being movable in the direction of the arrow in Fig. 1. The specific construction of these parts and the driving gearing for the rotary cutter have no bearing on my present invention, and they will not be further illustrated or described.

5 represents the lmife bar which may be of any usual or desired Construction. I prefer to form 1 it in the manner herein shown, and to provide iton its bottom face with a pair of ribs'66 extending longitudinally of the bar and separated by a recess, indicated at 7, so. that in machining these bars for the reception of the blade, it is only necessary to plane the bottom fa'ces'of the ribs. The'bar 5 is provided at each end with means for attaching it to the side frames of the mower, and I prefer to attach i the bar pivotally to the mower frames,- and in lawn mower construction.

to provide means for adjusting the bar and the knife carried thereby, around the axis of such pivotal connection, as is customary the knife bar'is provided at each end with an attaching lug Shaving an aperture 9 therein for the passage of a pivot-bolt 10 which secures it to the adjacent side frame of the mower, and each attaching-lug is provided in this instance on each side of the blade form a body portion 13 which is shown in detail in Fig. 4, and whichis provided with a flat central portion, having at each edge an upwardly extending lip, indicated at 14. This portion is formed of wrought metal, preferably wrought iron or wsoft steel, and may be made of comparati'vely inexpensive and low grade material, as

' it is not required to be tempered. The body portion of the knife is formed by rolling. machining, or in any other desired manner,

7 in the shape or form illustrated in Fig. 4,

and provides at each edge a longitudinal re-' cess 15 having an upwardly and outwardly inclined bottom face 16, and a shoulder 17 at its inner edge, which shoulder is preferably 7 perpendicular to the inclined bottom face 16 of the recess. The lower faces of the lips i are preferably inclined, as indicated at 18, and are substantially parallel with the upper faces 16. These bars may be rolled in any desired lengths and cut oif in sections to form knife bar bodies of different lengths accordin'g'to the requirements of the lawn mowers with which such knives are to be used. Knives are completed by fitting into the recesses 15-45 strips or edge pieces19 of steel of good quality, capable of being hardened, and producing a serviceable cutting edge. These strips are'seatedinthe-re- To this ,end

In the'formation of my improved "cutting V cesses 1515 with their inner edges abutting against the shoulders 17: 1;7 and their outer edges extending perpendicularly to the plane of thecentral portion of the main body,thus forming an acute angle cutting edge, indicated at 20, the upper face of which isinclined sharply upward. The edge portions19 of the knife arese'cured to the main body 13 preferably so as to form an integral structure therewith. This is accomplished by welding the edge pieces 19 to the body portion of the knife, and this is my preferred construction. They may be secured by brazing, riveting, or otherwise, but I prefer to weld these strips to the knife bar. Y

It will be noted that the resulting knife is of substantially channel shape. The edge portions are hardened in any usual or desired manner, and the resulting structure therefore produces a channel bar having hardened upwardly inclined cutting" edges which impart great stiffness and rigidity to the knife blade, while enabling it to be manufactured more cheaply than where the entire knife is formed of high grade steel. My improved knife'is secured in any usual or desired manner to the bottom ofthe knife bare, preferably in engagement with the lower faces of the ribs 66 thereof. In this instance I have shown the central portion 13 of the knife blade provided with screw holes, one of which is indicated at 21, to receive a retaining screw 22yextending into threaded apertures in the knife bar, and this is a convenient manner of attaching the knife bar to the knife.- It will be noted, by reference to Fig. .3, in which the sweep of the cutting edges of the rotary cutter isincheated by the dotted line 23, that when the knife is in'adjusted position, one of the acute angular edges 20 is presented'to the spiral cutting edges of the rotary cutter in such a manner that the upper face of the cutting 7 portion of the blade extends downwardly and rearwardly away from the path of the rotary cutting blades, so that as the cutting edge20 wears, the portion which frictionally engages the rotary cutting blades will be very small even when the knife has been considerably worn, thus enablingv the cutting edge to be used for a long time without materially increasing the frictional resistance and wear on the coeperating cutting blades,

which results where the upper face of the cutting edgeof the stationary knife is sub stantially horizontal. When one of the cutting edges has been worn away,'it is only necessary to detach the knife blade, and reverse it to present the other cutting edge 20, and thus'secure a fresh and unworn cutting edge. By my improved construction I am enabled to obtain the advantages of the channel knife bar construction, while greatly reducing the cost of manufacture. In addition tachea ness of manufacture, my improved channel knife is in fact, by reason of the co-action of the hardened edges, welded or otherwise secured in the shouldered recesses, at the edges of the knife body, more rigid than a channel knife formed by rolling the stock with upturned edges, and less liable to chip, and is more durable.

In forming the body of the knife I have stated that it may be rolled from stock in suitable lengths. I may also in some instances find it desirable to form this knife body from ordinary rectangular rolled stock of the form indicated in dotted lines in Fig. 4, in which case the recesses 1515 and the angular bottom faces 18 of the lip 14 may be machined by milling or planing portions to form the lips 1.4:, the cutting edge pieces 19 being welded or otherwise secured in the recess 15, in the manner hereinbefore described.

What I claim and desire to secure by Letters Patent is 1. A stationary lmife for lawn mowers, comprising a main body consisting of a fiat sheet of wrought metal of substantially uniform thickness throughout its main portions, and provided along a longitudinal edge, with an upwardly extending inclined lip of less thickness than the main portion of the blade, and a tempered cutting edge portion united to said lip and the adjacent portions of the main body, said edge portion lying upon the upper face of said lip and being provided with a cutting edge at the upper edge of its outer face, located above said lip and above the plane of the main portion of the main body of the knife. 7 2. A stationary knife for lawn mowers comprising a main body consisting of a fiat sheet of wrought metal, the central longitudinal portion of which is of substantially uniform thickness, and provided along its opposite longitudinal edges with upwardly extending oppositely inclined lips of less thickness than the central por tion of the main body, and forming a longitudinal recess on the upper side of each lip terminating at its inner edge in a shoulder, and a cutting edge portion of tempered steel located in each of said recesses on the upper faces of said lips and engaging said shoulders, and united to the main body to reinforce and stiffen the same, said edge portions being inclined upwardly in opposite directions, and each provided at the upper edge of its outer face with an acute ngular cutting edge located above the plane of the upper face of the central portion of the main body. 7

v 3. A stationary knife for lawn mowers comprising a main body consisting of a flat sheet of wrought metal having its central longitudinal portion of substantially uniform thickness and provided along its opposite longitudinal. edges with upwardly eX- tending oppositely inclined lips of less thickness than the central portion of the main body, each lip having its outer face substantially perpendicular to the plane of the central portion of the main body, and the upper edge of said face substantially in the plane of the upper face of said central portion, an angular recess being formed above each of said lips terminating at the inner edge in an angular shoulder, andseparately formed cutting portions of hardened steel welded to the main body, and lying in said recesses, said cutting portions being inclined upwardlyv in opposite directions, and each having its inner edge in engagement with one of said shoulders and its exterior face in alinement with the exterior face of the adjacent lip, the upper edges of said exterior faces of the said cutting portions forming acute angular cutting edges to engage the blades of the rotary cutter.

4. In a lawn mower, the combination with a main frame, a rotary cutter mounted.

therein, and a stationary knife bar secured to said main frame, of a stationary knife consisting of a flat sheet of wrought metal, the central longitudinal portion thereof being of uniform thickness and provided with means for detachably connecting it to the knife bar, said main body being provided along its longitudinal edges with upwardly extending oppositely inclined lips having their upper faces located below the plane of the central portion, and edge strips of hardened steel of substantially uniform thickness throughout secured upon said lips and maintained in oppositely inclined positions, and provided at their outer faces with acute angular sharpened cutting edges.

In testimony whereof I afiix my signature.


Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2496973 *Mar 16, 1946Feb 7, 1950Edward H WorthingtonBed knife for lawn mowers
US5293734 *Aug 2, 1990Mar 15, 1994Ransomes Sims & Jefferies LimitedBottom blade for grass cutting unit and method of producing
US7434380 *Mar 31, 2005Oct 14, 2008Textron Inc.Magnetic attachment of a bed knife in a reel mower assembly
WO1991003923A1 *Aug 2, 1990Apr 4, 1991Ransomes Sims & Jefferies LtdBottom blade for grass cutting unit
U.S. Classification56/294, 56/8, 56/DIG.170
International ClassificationA01D34/42
Cooperative ClassificationA01D2101/00, Y10S56/17, A01D34/42
European ClassificationA01D34/42