US1989315A - Road machine - Google Patents

Description

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Patented VJan. 29,' "19.35

UNITED sTATEs ROAD MACHINE Carl A. Gustafson, Minneapolis, Minn., assignor, to Caterpillar Tractor Co., San Leandro, Calif., a corporation of California Application June 15, 1932, semi No. 617,291

19 Claims.

application Serial N0. 533,179, led April 27, 1931,

relating to Road machine.

In road machines having a grader blade adapted for a wide variety of uses such as plowing, cutting high angle banks, ditching, etc., a great deal of cutting isdone at the end of the moldboard.

Providing cutting edges by bevelling the ends of the moldboard has not proven satisfactory be'- cause the ends of the moldboard wear irregularly and become ragged and shorter, necessitating premature replacement of the entire moldboard.

In grader blades where a separate cutting section is provided along the lower edge of the moldboard, the ends of both moldboard and cutting section can be bevelled but this construction has the additional disadvantage that a continuous cutting edge is not obtained. A

I'he invention disclosed herein solves the problem of providing cutting edges at the ends of grader blades by the provision of separate cutting sections, or end bits, which are adapted to be secured to the ends of the moldboard. vThere are many advantages of this construction. 'Ihe ends of the moldboard are protected from wear by the end bits. Its period of service is thereby materially lengthened and the cost of upkeep of the machine is diminished. An effective, eicient cutting edge can be maintained by reason of the fact y Y that the cutting edges are readily detached for sharpening, or for replacement by new. cutting edges, or extra cutting edges already sharpened and ready for attachment whenever needed, for example, when the road machine is at work at a place inconvenient to the necessary facilities for Y sharpening. 'Ihe end bits can be made of inaterial especially suitable for cutting'edges and so shaped that they cut better and wear much longer. A continuous cutting edge is presented to the earth atthe end of the moldboard. The moldboard is well-shed with cutting sections along all the edges which could be presented to the earth, namely, the bottom and the ends, so that a moldboard equipped in this manner furnishes a graderv blade of superior characteristics and capable of performing a variety of operations, heretofore not expected of a grader blade. Thus the utility of the road machine, as an implement, is increased and its eld of work is extended.

A particularly advantageous feature of the preferred form of end bit or cutting section disclosed herein is the provision of a longitudinal abutting edge on the end bit which is adapted to engage the end of the moldboard to absorb most of the strain imposed on the connection during operation thereby preventing the transmission 0fv any shearingstresses to the fastening means lengthwise of the moldboard. This abutting edge is preferably in the form of a rib on the back ofthe bit and it serves also as a stiffener to enable the necessary strength and rigidity to be obtained without making the bit excessively thick or using an unnecessary amount of metal. Another advantage obtained by the construction of the preferred embodiment is that the ends of the moldboard and the cutting sections along the lower edge thereof may be left square, the cutting edge of the end bit being formed substantially thicker than the `portion thereof which is bolted to the moldboard, whereby no surface other than the cutting edge itself is presented to the earth. Preferably the end bit overlaps the end of the cutting section attached to the bottom of the moldboard, so that its end need not be bevelled, but is left square. A plurality of cutting sections can be employed on the bottom edge of the moldboard and since by the use of end bits their ends can be left square, they can be interchanged to compensate for wear and can be made alike, thereby facilitating manufacture and replacement. l

It has been found that the life of a cutting section and thedulling period thereof depend to a large extent not only on the character of metal employed but also upon the method of manufacture. In the novel method of forming cutting sections described herein, I have a method particularly adapted for producing cutting sections, which is eiilcientl and economical, which produces a section of superior quality and durability. Sections produced by this method are capable of long life and service and have a lowv manufacturing cost.

Fig. 1 is a front elevationpf the blade of a road machine.

Fig. 2 is a rear elevation.

Fig. 3 is a view of the blade'in plowing position.

Figs. 4 and 5 are views ofthe en d bit shown in Figs. 1 and 3 and on the left end of the blade in Fig. 2.

Fig. 4 is/a side elevation. l

Fig. 5 isfa section fromA une 5 5 1n Fig. 4.

Figs. 6 to 10 are views of a preferred form of end bit shown applied to the right end of the blade in Fig. 2.

Fig. 6 is a front elevation of the end bit applied to theblade.

Fig. 7 is a side elevation with parts broken away to show the fastening means.

Fig. `8 is a fragmentary side elevation.

Fig. 9 is a fragmentary bottom view taken from line 9 9 in Fig. 8. v Fig. 10 is a section taken from line 10-10 in Fig. 7.

Figfll is a diagram illustrating the method for producing the end bit in its preferred form. Fig. 12 illustrates the roller section.

Description of device The invention is. disclosed as embodied in a grader, a portion of the main framework of which is shown at 25 in Fig. 1. The frame of the machine is suitably supported on wheels and axles, wheels 200, 201 being the rear wheels of the vehi cle. Wheels 200, 201 are rotatably mounted on lbell cranks 228, 229 pivoted at 204, 205 in brackets 206, 207 secured to the ends of rear axle 208. The upwardly extending arms of cranks 228, 229 are interconnected by bar 230 which is shifted laterally to tilt the wheels.

Blade 300 (Fig. 1) consists of cutting edges 301 secured to mold board 302 and end bits 303, 304 secured to moldboard 302 and overlapping cutting edges 301. Angle bracket 305 (Figs. 1 and 2) is secured to moldboard 302 and angle 306 is secured to the trailing edge of angle 305. Brackets 309 are secured to angle bracket 305. Corresponding brackets 313 are secured to moldboard 302. Brackets 309. 313 are used for connecting the blade to the circle assembly in different positions.

Beam 317 (Fig. 3) has a central portion 318 l which is bent into a semi-circle of substantially the same radius as circle 315. This central semicircular portion of the beam encompasses approximately one-half of the circle and is riveted thereto. End portions 319, 320 of beam 317 extend tangentially from the circle and downwardly, their lower ends being apertured for Yconnection to brackets 309 (Fig. 1) on angle 305 by means of pins 323. In order to rigidly 'connect the ends ofthe beam to the circle,

`the axis of pins 323 to alter the inclination of cutting edges 301 to the surface of the ground. To lock the blade in adjusted position, links 335 are connected by pins to brackets 313 on the moldj board. The inner faces of links 335 are serrated at 339 to engage with corresponding serrations in clamping blocks 341 on the beam. A plurality of brackets 309, 313 is provided so 'that the blade may be connected to the beam in different transverse positions with respect. to the surface `so that the blade can be made t'o extend farther outwardly to the left or -right of the machine as desired.

The Vcircle is revolvably mounted in a framework consisting of forwardly converging' side bars 342,343 and rear cross bar 344. vThe rear end of side bar 342 is rigidly connected with the right end of bar 344' by bracket 345 to the webs 346, 347 of which they are bolted. Similarly the rear end of side bar 343 is rigidly connected with the left end of bar 344 by bracket 348. The front ends of the sidebars are secured to a hollow connection block 349 (Fig. 3)* in which is pin 350 for a purpose hereinafter described. The intermediate portions `of the side bars are rigidlyconnectedtogether by casting 351. The inwardly cxtendim flange of the circle rests on arcuate M352 (Fig. 1) which are formed integrally provided in casting 351. The arcuate ledges provide a support for the circle on which the circle can be revolved and rub irons are provided which serve to take up wear in the parts and to reduce the amount of play between the circle and the support.

The circle supporting framework is connected by draw bars 359 (Fig. 3) to the front end of the main frame where a rearwardly extending fork 361' is provided. Drawbars 359 converge forwardly to a connection 362 to which they are bolted. In connection 362 is a bolt 363 having an apertured head 364 which is connected by pin 365 in fork 361. zontal plane about the vertical axis of pin 365, and, due to the rounded edges of the aperture in the head 364 and the wide spacing of the jaws of the fork 361, bolt 363 is capable of a limited oscillation in the vertical plane, as well. The rear ends of drawbars 359'are pivotally connected to the circle supportingframeworkat 367. By reason of these pivotal connections between the drawbars and the circle supporting framework, the framework, together with the circle and the blade, can be raised and lowered with respect to the drawbars, or, in other words, the angle between the drawbars and the plane of the circle can be varied. Also, the drawbars, together with the circle and blade assembly, as a unit, are capable of a limited universal movement about the intersection of the axes of pin 365 and bolt 363 as a center.

To summarize the movements of adjustment of which the circle is capable, they are, an arcuate movement in a horizontal plane about the vertical axis of pin 365; an arcuate movement in vertical planes containing the axis of pin 365; oscillation about the axis of bolt 363; a jack-knife movement between the circle and the drawbars; and oscillation of the `circle about its center. The desired circle adjustment is usually obtained by combinations of these movements.

The ends of rear cross bar 344" (Fig. 1) of the circle supporting framework are connectedby ball and socket joints 400, 401 to links 402, 403 which telescope in links 404, 405 and which can be locked together in different positions to provide lift links of various lengths. Links 404, 405 are connected to lift arms on shafts mounted on the main frame.

Means are provided for (1) shifting the center of the circle transversely of the machine or about the center of pin 365; (2) shifting the circle on its own center, and (3) adjusting the plane of the circle with respect to the drawbars.

(1) For shifting the center of the circle, the supporting frame vof the circle isadapted to be variously connected by a link toa rack on the main frame lwhich can be slidtransversely of the main frame. Rear cross bar 344. (Figyl) Lof the circle supporting framework is provided with apertures 500, 501 adjacent its ends for connection to a link 502 having a hooked end. The other end of link 502 is connected to the rack on the main frame. Movement of the rack causes Bolt 363 can swing in a horilink 502 to draw the circle supporting frame i transversely and thereby shift the center of the of circle 315. Rack 521 is engaged by a'pinion keyed to the lowerend of a vertical shaft which is journaled in casting 351 (Fig. 3) and in houswith 345 and 348. Similar ledges are ing '524.which is secured to casting 851. Within 7 5 cylindrical surfaceof the front face of the moldy housing 524 bevel gearing connects the vertical shaft to a horizontal shaft which is connected by universal joint 528 to square shaft 529which telescopes in hollow square shaft 530, the upper end of which is suitably connected to-operating mechanism therefor on the main frame. Rotation of shaft 530 causes the circle to be shifted about its center. This adjustment is made to vary the angle of cutting edges 301 with respectI to the longitudinal axis of the circle supporting frame, or, in other words, with respect`to the line of draft.

(3) For adjusting the plane of the circle 'with respect to the drawbars, there is provided a screw 560 (Fig. 3) the lower end of which is provided with an eye 561 through which pin 350 passes.

Screw 560 is threaded through hub 562 of bevel.

gear 563 and passes through apertures in bracket 566 which is secured to drawbars 359. The bracket is arranged so that bevel gear A563' and ,its hub 562 are restrained against axial movement, rotation thereof resulting in feeding screw 560 axially. A plate 567 is secured to bracket 566 and extends downwardly between the forward ends of side bars 342, 343 as a guide therefor and is provided with lugs 568 which serve as a limit stop. Bracket 566 is providedwith an apertured boss 569 to support stub shaft 570. Bevel pinion 571 is secured at the `forward end of stub shaft 570 and meshes with bevel gear 563. The rear end of shaft 570 is connected by universal joint 572 to hollow square shaft 573 within which square Y shaft 574 telescopes. Shaft 574 is connected to operating mechanism on the main frame. Operation of shaft. 574 turns bevel gear 563 to project or retract screw 560 thereby adjusting the circle with respect to the drawbars.

From the foregoing description it is seen that'v the adjustment of the plane of the circle with respect to the drawbars either raises or lowers the front end of Vthe circle supporting frame. Such movement varies the angle ofcutting edges 301 with the surface of the ground if the blade is in its transverse position as shown in Fig. l, and raises or lowers the front end of the blade if it is rotated from its transverse position as shownin Fig.- 3, which illustrates one of the uses of this adjustment, the blade being positioned to actas a breaker plow.

Blade and end bits oiset to provide a portion 302B to receive cutting sections 301 which have the same curvature as the moldboard; By this arrangement the front faces of moldboard 302 and cutting sections 301 provide a continuous cylindrical surface which permits easy passage ofl earth without clogging. The longitudinal edges of cutting section 301 are beveled at 301A and 301B, the bevel 301A forming the cutting edge, and the bevel 301B serving to t the cutting section into the offset of the moldboard without interrupting the cylindrical surface. Cutting sections 301 are removably attached to oiset 302B by means of bolts 301C. The end s 302C (Fig. 10) of moldboard 302 are square, that is, their surface is normal to the board. The ends 301D (Fig. 9) of cutting sections 301 are also square and are flush with the ends 302C of the moldboard when assembled. As shown in Figs. 1 and 2, two cutting sections 301 are placed end to end at the bottom of the moldboard to provide the bottom cutting edge of the blade. These cutting sections are substantially identical and, are interchangeable, as shown by vthe symmetrical arrangement of bolts 301C in Fig. 2. They are also readily replaced by similar .sections to maintain the efficiency of the lower cutting edge.

End bits 303, 304 are shown in detail in Figs; 4 and 5, from which it appears that the bottom edge of the end bit is provided with a bevel 303C to form a cutting edge and the sides arev beveled at 303A and 303B (Fig.'5) to form a cutting edge on the outer side of the bit and a smooth joining edge on the inner side to facilitate passage of earth over the faces of the moldboardA and end bit.

Preferred form of end bit (600 series numerals) other hand, terminates at squareshoulder 604 on rib 605, which extends throughout the length of end bit 600 on its back. End bit 600 extends along the end of moldboard 3 02 and its bottom portion overlaps the outer end of cutting section 301. Shoulder 604 of rib 605 abuts end 302C of moldboard 302 and end 301D of cutting section 301. Square holes 617 are provided along the inner edge of end, bit 600 and are countersunk at 607 for the reception of conical headed squareshanked bolts 606 which pass through alined apertures in moldboard302 to fasten end bit 600 in place thereon, bolts 606 being fitted with nuts 608.

The outer portion 609 (Fig. 10)` of end bit-600 is thicker than inner portion 601, the rear surface 610 being spaced further from frorit surface 603 than rear surface 602. The cutting edge i's formed by bevel 611. Bevel 612 along the bottom edge of end bit 600 provides acontinuation ci the cutting edge of 4cutting section 301. An inspection of Figs. 7 to 9 will show that the lower corner of the blade is thus provided with a thick,

er, stronger cutting edge. This is a point in the blade where considerable wear takes place. No tice in-Fig. 7 that the combined thickness of portion 601 of end bi't 600 and of cutting section 301 is available for receiving extra stresses. Bevel 301A on cutting section 301 and bevel 612 on portion 601 of end bit 600 cooperate at this point to form a cutting edge which is stronger and more durable than the cutting edge of section 301 alone. Beyond the end 'of section 301,', end bit 600 is made thicker in portion 609 and is provided with a bevel 615 on the rear face, which bevel is substantially para11e1 to bevei- 301A as shown in Fig. 8. 'Ihe lower outside corner of end bit 6110 is cut off at 614 which is the line of intersection of bevels 611 and 612 to make a more durable point and one less apt to break oi than a square corner. Bevel 6-13 alongthe inner-edge of end bit 600 provides alsmooth surface for passage of earth over the end bit and moidboard. j Bottom bolt 606 (Fig. 7) passes through end bit 600, cutting section 301 and offset portion 302B of moldboard 302.

Rib 605 protects the ends of moldboard 302 and cutting section 301, positions end bit 600 thereon, prevents the end bit from working. loose, and transmits end thrusts and twisting strains on the end bit directly to the moldboard, thereby relieving the bolts 606 from strains tending to break or wear the bolts loose.

The blade is provided with a substantially continuous cutting edge around three sides, namely the bottom and sides. As the blade is symmetrical, one-half of this continuous cutting edge comprises 611, 614, 612 and 615, 612 and 301A together, and 301A.

Method of producing end bits The method herein disclosed can be employed for making end bits of different types and forms, and for illustration will be described as producing end bit 600.

The seven steps in the method are illustrated diagrammatically in Fig. 11

(1) A hot billet 620 is passed through rolling means 1 to produce a strip 621 having the crosssectional shape shown in Fig. 12. Comparison of Figs. 10 and 12 show s that the cross-sectional shape of the rolled strip 621 is the cross-sectional shape o'f the end bit 600, and as the two are identical the reference numerals applied to the end bit section in' Fig.A 10 have been applied to the rolled strip section in Fig. 12. As the end bit section has already been described, no further description of the strip section will be given.

Note in Fig.. 11 that bevels 611, 613, and rib 605 run longitudinally in the strip, or parallel to I the material through the rolls. V

(2) Strip 621 is passed through severing means 2 which cuts the strip into pieces 622 of equal length. Pieces 622 being approximately the length -of the end bit 600, as will appear.

(3) Piece 622is passed to beveling vmeans 3 where the end of the piece is beveled. The resultant piece 623 has bevels 612 and 615 formed thereon and is of 'the same length as the end "bit, Thisoperation can be performed'by forging.

The operation of forming bevels 612 and 615 automatically produces corner-614 as it is -means 5.

the line of intersection of the planes of the bevels. (4) Piece 623 is passed to perforating means 4. 'I'he resultant piece 624 has square holes 617 therein.

(5) Piece 624 is passed to countersinking The resultant piece 625 has square holes617 countersunk at 607.

0(6) Piece 625 is passed to forming means 6.

The resultant piece 626 has the requisite curvature for the end bit to ilt the moldboard.

(7) Piece 628 is passed to polishing means 7.`

.The resultant piece 627 is the nished end bit 600 ready for attachment to cutting section 301.

I, therefore, claim as my invention:

1.A scraper blade end bit -formed integrally and having an eve concave front face anda convex back fac'e having a longitudinal apertured blade engaging portion, a second thicker moldboard 302 and longitudinal portion, and a longitudinal rib intermediate said portions having a blade engaging face, said blade engaging. portion having abeveled edge, said ,second portion having a beveled cuttingedge, the lower end of said end bit being beveled on the concave face thereof and on the convex face adjacent said second portion.

2. A scraper blade en`d bit having the same transverse coniiguration as that of the scraper blade and shaped to be detachably and rigidly.

secured to said scraper blade so as to overlap a face of said scraper blade and tolie flush against said face to provide a projecting end ,portion of vthe scraper blade proper which lies substantially 'formed thereon, one of said cutting edges forming the end cutting edge of the scraper blade proper.

3. A cutting section for grader blades having a concave front face and a convex back face, the side edges thereof being bevelled said section lying substantially in the surface of said grader blade and being shaped to be detachably and rigidly secured to the grader blade so as to overlap a face of said grader blade and .to lie ush against said face to provide a projecting end portion of the grader blade proper when secured thereto, one of said bevelled side edges forming the end cutting edge of the grader blade proper.

4. A cutting section for grader blades having substantially parallel opposite bevelled faces, a stiiening rib intermediate said `faces and parallel thereto, and a third bevelled face substantially normal to said first named faces.

5., A cutting section for grader blades having longitudinal portions of different thicknesses and a rib intermediate said portions characterized in that said portions and said rib are formed by passing a metal bar through rolling means having the desired contour.

6. In a road grader, a blade having a long edge l and a short edge, means to adjust said blade to cause either edge to be placed in working relationship with the ground, and members secured to said blade along said edges and having cutting edges formed thereon,. said members lying in rand substantially continuing the surface of said blade.

`7. As an article of manufacture, a. metal cutting section adapted for detachable connection to a moldboard, comprising longitudinal portions of diierent thickness, a rib intermediate said portions, said portions and said rib being formed in a single step by rolling the heated metal, and a plurality of cutting edges formed by beveling.

8. Aiscraper blade end bit shaped to be secured to said scraper blade so as to lie substantially in and continue the surface of said scraper blade when secured thereto, said end bit forming a detachable cutting section for an end of said scraper blade and having a lower cutting edge cooperating with the lower cutting edge of the scraper blade, and also having a second cutting edge extending in a direction transverse to said lower cutting edge to provide an end cutting edge for said scraper blade, said cutting edges lying sub.- stantially in the surface of said scraper blade.

9. A scraper .blade end bit formed integrally and shaped to beV secured to said scraper blade so as to lie substantiallyin and continue the surface of said scraper blade when secured thereto, the shape of said end bit being such that the projection thereof on a fiat planar surface forms a rectangle, said end bit forming a detachable cutting section for an end of said scraper.v blade and having a lower cutting edge cooperating with the lower cutting edge ofthe scraper bladeY and `also having a cutting edge extending\ in a direction transverse to said lower cutting edge to provide an end cutting edge for said scraper blade, said cutting edges lying substantially in the surface of said scraper blade.

10. A scraper blade end bit shaped to be secured to said scraper blade so' as to' lie substantially in and continue the surface of said scrape;` blade when secured thereto, said end bit forming a detachable cutting section for an end of said scraper blade and having a lower cutting edge cooperating with the lower cutting edge of the scraper blade, and also having a second cutting edge extending in a direction transverse to said lower cutting edge to provide an end cutting edge for said scraper blade, said cutting edges lying substantially in the surface of said scraper blade,

and means integral with said end bit and extending in a direction transverse with respect to said lower cutting edge to provide a reenforcing abutment for engaging an end of said scraper blade.

- 11. A scraper blade end bit shaped to Abe setially in and continue the surface of said scraper blade when secured thereto, said end bit forming a detachable cutting section for an end of said scraper blade and having a lower cutting edge cooperating with the lower cuttingedge of the scraper blade, and also having a second cutting edge extending in a direction transverse to said lower cutting edge to provide an end cutting edge for said scraper blade, said cutting edges lying substantially in the surface of said scraper blade, and means integral with said end bit and extending in a direction transverse with respect to said lower cutting edge to provide a reenforcing abutment for engaging an end of said scraperl blade, the portion of said end bit between said means and said second cutting edge being thicker than the remaining portion of said end bit.

12. A scraper blade having a lower cutting-edge and a detachable end bit secured to each end of said scraper blade, said end bits being shaped to lie substantially in and continue the surface -of said scraper blade to thereby form vpart of the scraper blade proper, each end bit having Va lower cutting edge cooperating with the lower cutting edge of the scraper blade, and also having a second cutting edge extending in a direction transverse to said lower cutting edge -to-prcvide an end cutting edge for said scraper blade, said cutting edges lying substantially in the surface of said scraper blade.

13. A scraper blade having a lower detachable cutting section 'providing a lower cutting edge, a detachable end bit secured to an end of said scraper blade and overlapping said lcutting sec--l tion, said end bit being shaped t0 liesubstantially in and continue the surface lof said scraper blade' to thereby form part' of the scraper blade proper,

the end bit having a lower cutting edge cooperating with the lower cutting edge of the scraper blade, and also-having a second cutting edge.

. vextending in a direction transverse to said lower cutting edgeto provide anend cutting edge for said .scraper blade, said cutting edges lying sub- Y the surface of said scraper blade,

and a plirlity of fastening fmembers passing through said end bitforsecuring' said end bit,

-portion of said end bit.

19.' A scraper-,blade structure including as part o able but rigidly secured end bit 'havinga-lower' said fastening members being arranged to extend in a direction transverse with respect to said lower cutting edge and including a .member passing through saidlower detachable cutting section. 14. In a device of the class described, `a mold board having a lower edge and an end lying in a plane extending substantially at right angles to said edge, an end. bit detachably secured to said moldboard adjacent said end thereof to form a scraper blade, said end bit having a portion thereof in ush engagement "with a face of said moldboard, the remaining portion of said end bit extending beyond said end of said moldboard, and a cutting edge on said projecting portion to provide an end cutting edge -for said scraper. blade, said cutting edge being substantially parallel to said moldboard end and lying substantially in the surface of said moldboard.

15. In a device of the class described, a moldboard having a lower edge and ends lying in planes extending substantially at right` angles to said edge, an end bit detachably and rigidly se- `curedto said moldboard adjacent each end thereend bit extending beyond the end of the vmoldcured to said scraper bladeso as to lie substan- `surface of .said moldboard, and another cutting edgeon each end bit cooperating with the lower edge of said scraper blade.v A

16, An end bit for scraper blades having substantially parallel opposite' bevelled edges, reenforcing means integral with said -bit intermediate said edges and parallel thereto, and a thirdl bevelled edge substantially normal to said ilrstmentioned edges.

17. A detachable end bit fora scraper blade, having a cutting edge lying substantiallyl in the surface of said scraper blade to provide the endl cutting edge of said scraper blade,lsaidend' bit cutting edge lying in a plane extending substan tiallyvat right angles to the lower edge of said scraper blade, and means integral with said end bit and substantially parallel to said end bit cutting edge to provide an abutment.

18. A detachable end bit for a scraper blade,v l

having a cutting edge lyingsubstantially inthe surface of said scraper blade to provide the end cutting edge of said, scraper blade, said end bit cutting edge lying in-a p lane extending substantially at right angles to the lower edge of said scraper blade, andmeans integralrwith said end bit vand substantially parallelto said end bit cutting edge to provide an abutment, the portion of said end bit between said means and saidcutting edge thereof being thicker lthan vthe remaining of the blade proper a scraper blade and a. detachedge to cooperate with the lower-,cutting edge of .the scraper bladefandanother cutting 'edge-extending in a directiontransverse to the lower cuttingedge 'of the blade and serving as the normal end'edge for the blade, said endbit lying flush stantially thesurfaceof vsaidisc'zraper blade.-

` fcsanafcipsrarsonf '1o against said scraperblade` and '.ontinuingsubf

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