US2169946A - Scraper - Google Patents

Description

Aug. 15, 1939 H. c. FRENTZEL. JR ET AL SCRAPER Filed June 25, 195'! 4 Sheets-Sheet 1 mew ATTORNEY.

H. c. FRENTZEL. JR., El AL 2,169,946

SCRAPER Aug. 15, 1939.

I 4 Sheets-Sheet 2 Filed June 25, 1957 INV NTORS j ATTORNEY.

I Aug; 15, 1939- H. c. FRENTZEL. JR., E-FAL' 2,169,946

SCRAPER 4 Sheets-Sheet 5 Filed June 25, 1937 Patented Aug. 15, 1939 UNITED STATES PATENT orrics SCRAPER Application June 25, 1937, Serial No. 150,232

19 Claims.

Our present invention relates generally to improvements in the art of excavating and grading, and relates more specifically to improvements in the construction and operation of scrapers of the type which are capable of both leveling ground and transporting excess earth from place to place.

An object of our present invention is to provide an improved grading and transporting 1o. scraper assemblage which is simple and durable in construction, and which is also highly eflicient in operation.

Many so-called dig and carry scrapers have heretofore been proposed and used with more 5. or less success, but all of the prior scraper assemblages are objectionable for various reasons. Such a mechanism must not only be relatively simple and extremely durable in construction. but it must also possess large carrying capacity within a limited space and must furthermore be conveniently operable with minimum power. Due to the varying nature of the soil, many difficulties are encountered in attempting to adapt the same scraper assemblage for all uses, and some materials which may be readily loaded are diflicult to unload and vice versa. It has also been found that the disposition of the cutting blade and of the dirt receiving bowl of such scrapers are important factors in obtaining maximum efliciency; and while hydraulic jacks have heretofore been utilized to actuate the various parts of dig and carry scrapers, these jack assemblages have been rather complex, obstructive, and ineffective in use. These and many other difliculties have combined to make the prior scrapers and dirt movers of this general type rather unsatisfactory for diversified usage and have materially restricted the capacity and general utility thereof.

It is therefore a more specific object of our present invention to provide an improved dig and carry scraper which obviates the various objectionable features of. the prior devices, and

which has a wider range of use with minimum power consumption for given capacity.

Another specific object of our invention is the provision of a new and useful power actuated dirt mover wherein the various movable parts are adjustable with the aid of simplified and effective hydraulic jack mechanism.

A further specific object of our invention is to provide improved mechanism for enabling the operation of the loading and unloading rig of a 55 power scraper with minimum effort and maximum speed, so that least time is required during normal operation of the equipment.

Still another specific object of the invention is the provision of a scraper assemblage which is extremely rugged and durable in construction, 6 and which may be conveniently manufactured and subsequently operated at moderate cost.

An additional specific object of our present invention is to provide various improvements in the construction of scraper frames and dirt carrying 30 bowls, whereby the strength and utility thereof. is enhanced to a maximum. while the general dimensions are reduced to a minimum without sacrificing capacity, thus vastly improving the appearance and usefulness of such devices. 15

These and other objects and advantages of our invention will be apparent from the following description.

A clear conception of embodiments of the various features constituting our present invention, 20 and of the mode of constructing and of operating scrapers built in accordance with our improvements, may be had by referring to the drawings accompanying and forming a part of this specification wherein like reference characters designate the same or similar parts in the various views. f

Fig. l is a rather diagrammatic longitudinal vertical section through an improved dig and carry scraper, showing the dirt carrying bowl in 30 loading or dirt receiving position;

Fig. 2 is a similar section through the scraper, showing the bowl loaded but not elevated away from the cut, and the front apron lowered to confine the load;

Fig. 3 is a similar sectional view showing the elements of the scraper in load carrying or transporting position;

Fig. 4is another similar sectional view illustrating the parts in bowl unloading position;

Fig. 5 is a more detailed side view of a commercial scraper assemblage, showing the bowl in loading position with the front apron lowered;

Fig. 6 is a rear view of the commercial assemblage, some of the hidden details having been dotted in the left half, but omitted from the right half of the view, for the sake of clearness;

Fig.7 is a fragmentary part sectional side view of the rear bowl elevating hydraulic jack;

Fig. 8 is a full top view of the commercial assemblage of Figs. 5 and 6; and

Fig. 9 is a fragmentary longitudinal horizontal section taken through one side of the main frame of the commercial machine.

While our invention has been shown and describedherein as being specifically embodied in a dig and carry scraper of the type embodying a bowl with rear and front aprons cooperable with the bowl and movable relative thereto by means of hydraulic Jacks, it is not the intent to thereby unnecessarily restrict the scope, since some of the improved features are obviously more generally applicable to other types of scrapers.

Referring to the drawings, the improved dig and carry scraper unit shown therein, comprises in general a main frame I 4 pivotally supported at its front central portion upon a wheeled draft carriage l5 and having rearwardly extending laterally spaced hollow side arms I6 which are rigidly interconnected at their rear ends by a transverse beam IT; a main open ended dirt carrying bowl having a flat bottom l8 provided with a front cutting blade I! and being rigidly suspended by parallel side walls 20 from the side arms l6; a rear apron 2| normally closing the rear open end of the bowl and movable between the side walls 20 and along the bowl bottom l8 toward the blade l9 by means of a hydraulic jack 22; a front apron 23 swingably suspended from the bowl side walls 20 and movable toward and away from the open front end of the bowl and the blade I! by a second hydraulic jack 24; an auxiliary frame 25 having its front end pivotally connected to the rear lower portion of the, bowl by a transverse pivot 26, and its rear portion pivotally suspended from rear transporting wheels 21; and a third hydraulic jack 28 interposed between the medial portion of the auxiliary frame 25 and a set of laterally spaced ears 29 rigidly attached to the cross-beam ll of the main frame M.

The main frame l4 with its'side arms 16, crossbeam I 1, and the bowl, are preferably formed of heavy metal plates welded together to provide a rigid integral structure, so that the bowl as sembiage will swing with the main frame about the pivotal support afforded by the draft carriage IS. The draft carriage I 5 is adapted to be connected to a propelling tractor with the aid of a suitable draw bar; and the tractor is'ordinarily provided with a liquid circulating pump driven by the propelling motor of the vehicle, and with control levers manpulable by the driver, for effecting operation of the several hydraulic jacks 22, 24, 28. Such location of the pump and control levers upon the traction vehicle, is well known in the art, but the main frame l4 of our improved scraper, is preferably formed with a liquid supply reservoir 30 of ample capacity formed directly therein above the carriage l5. The reservoir 30 has flexible suction and return pipes 3|, 32 communicable with the liquid circulating pump on the tractor, and control valve mechanisms 33, 34, 35 which are mounted upon the mainframe I 4 of the scraper above the reservoir 30 are operable through flexible cable connections 36 by the manually manipulable control levers on the tractor so as to effect independent operation of the three hydraulic jacks 22, 24, 26. While the speciflc system for controlling the delivery of liquid to and from the hydraulic jacks, constitutes no essential part of our present invention, the formation of the main frame l4 with the liquid supply reservoir 30 directly therein, and the disposition of the valve mechanisms 33, 34, 35 directly upon the frame i4 adjacent to this reservoir 30, are features of this improvement; and the hollow side arms I6 are formed to receive and to enclose liquid conducting pipes 31, one set of which communicates with the valve mechanism 33 and G 1- ducts liquid to and from the rear jack 22, and

the valve mechanism 35 and conducts liquid to and from the rear jack 28, see Figs. 5 and 9. The remaining valve mechanism 34 is connected by suitable flexible conduits (not shown) to the front hydraulic jack 24, and as previously indicated, the three jacks 22, 24, 28 are operable independently of-each other.

The bowl bottom l8 has a substantially flat upper surface and the cutting blade i9 is reversibly attached to the front of the bottom I! being disposed at the proper inclination so as to insure most eflicient severance of the ground when the bowl is in lowered position. The side walls 26 which rigidly suspend the bowl bottom I6, from the side arms I6 of the main frame i4, and from the ends of the box-beam H, are preferably disposed parallel to each other and extend rearwardly beyond the bottom l8 so as to form a support for the pivot 26; and the bowl bottom It is provided with a large central cut-out or opening 38 at its extreme rear end, which does not however extend up to the adjacent port'ons of the side walls 20. It is to be noted, that the construction of the main frame l4 and of the load retaining bowl, is such that the entire top of the bowl is open and unobstructed at all times, thus permitting free loading of the scraper from above with the aid of an excavating shovel or the like.

The rear apron 2| which normally closes the rear end of the load confining bowl, is movably supported directly upon the bowl bottom 18 by means of a pair of rollers 39 coacting with the upper surface of the bowl bottom beyond the ends of the opening 38, and is guided for free movement between the parallel side walls 20 by means of a pair of guide rollers 40. The rollers 39 are rotatable about aiined horizontal axes while the rollers 40 are rotatable about substantially vertical parallel axes, and these rollers provide anti-friction supports and guides for the rear apron 2|. The lower extremity of the apron 2| carries a pivoted scraper flap 4| which constantly engages the bowl bottom i 8 forwardly of the opening 38 and is movable along the upper surface of the bowl bottom as the apron is advanced therealong. The rear,apron 2| is adapted to coact with the transverse beam l'! of the frame I4, when in retracted position, and the apron 2| is also provided with laterally spaced rearwardly projecting parallel arms or brackets 42 which project from within the bowl beneath the cross-beam H as clearly shown in Figs. 1 to 4 inclusive. The brackets 42 are disposed on opposite sides of the hydraulic jacks 22, 28 and between the spaced ears 2! of the main frame l4, and the rear extremities of the brackets 42 are pivotall'y'attached to the swinging ends of laterally spaced levers 43 which are swingably suspended from the ears 2!! by alined pivots 44. The hydraulic jack 22 which is swingably suspended from the lower rear portion of the bowl and from the front portion of the auxiliary frame 25 by means of the pivot 26 which connects these elements,.has a movable piston 45 which is pivotally attached to the medial portions of the levers 43, so that operation of the jack 22 will produce swinging motion of the levers 43 resulting in movement of the rear apron 2i within the dirt confining bowl.

The front apron 23 is swlngably suspended from the side walls 20 of the scraper bowl by means of side arms 46, the forward ends of which are rigidly attached to the apron 23 and the rear extremities of which are secured to the outer sides of the walls 28 by pivot pins 81, see Figs. and 8. The apron suspension arms 46 thus swing externally of the bowl, and the apron they will not interfere with the 23, has integral parallel side walls or flanges 48 which are slidable along the inner surfaces of the bowl walls 28 so as to prevent spilling of the load. The lower extremity of the front apron 23 is moreover provided with a transverse cutoff plate 49 which is cooperable with the cutter blade l9 when the front apron is lowered to close the front end of the bowl as indicated in Fig. 2; and the front apron actuating jack 24 is suspended from the forward portion of the main frame It by means of trunnion pivots 50 and has a movable piston 5| which is pivotally attached to the external front portion of the apron 23 as shown in Figs. 5 and 8.

The auxiliary rear frame 25 is preferably of rugged construction and may also be formed of heavy metal ,plates welded together, and as previously indicated, the front portion of this frame 25 is connected to the rear lower portion of the bowl assemblage by the pivot 25 while the rear of the frame is pivotally suspended from the transporting wheels 21. The wheels 21 are pref erably disposed within the path of action of the scraper as defined by the bowl side walls 20, as indicated in Fig. 8; and the lower front portions of these walls are provided with laterally outwardly projecting cutters 52 as shown in Fig. 5, for the purpose of cutting a clearance path for the lower bowl extremity. The hydraulic jack 28 for elevating the rear portion of the main frame l4 and the bowl suspended therefrom, is swingably suspended fromthe ears 28 by trunnion pivots 53, and has lower end of which is pivotally attached to the medial portion of the auxiliary frame 25 as depicted in Figs. 5, 6, 7 and 8. In order to assist the jack 28 in raising the bowl and its load, a series of four heavy compression springs 55 are interposed between the relatively movable elements of the jack 28 as illustrated in Fig. '1. These springs 55 are housed within and coact with the upper ends of tubular casings 56 which are firmly attached to the jack cylinder, and the lower ends of the springs 55 react against a lower plate 51 attached to the piston 58. The arrangement of elements is obviously such that when the bowl and its load are elevated tothe position shown in Fig. 3 by expansion of the jack 28 with liquid under pressure, the springs 55 will simultaneously expand and assist the jack 28 in raising the load; whereas contraction of the jack 28 by gravity and liquid under pressure will compress the springs 55 and store therein sufficient energy to make them available as an aid to load lifting operation. The jack 28 and the spring casings 56 are of such dimensions that swinging motion of the levers 43, and the ears 28 which are formed integral with the cross-beam ll of frame l4, may be additionally stiffened andreenforced by cross-braces 58 and side braces 59 as in Figs. 5 and 8. The rear mechanism of the scraper may be additionally protected by a housing 88 as shown in the diagrams of Figs, 1 to 4 inclusive, and the front jack may be protected from the load by a guard 6| as shown in Fig. 5. Other exposed and relatively delicate portions of the scraper assemblage, such as the valve mechanisms 33, 34, 35, may also be protected by'suitable guards.

During normal use of the improved scraper, the front carriage i5 is connected to a draft vehicle a movable piston 54, the

of each other and as desired, by the tractor op-.

erator, and the supply of liquid for actuating these Jacks is derived from the supply reservoir 30. when the several elements are positioned as shown diagrammatically in Fig. 1, and the scraper is being advanced along the ground, the cutter blade I8 is being driven through the soil and is delivering a load 52 into the bowl and against a the rear apron 2| which abuts against the crossbeam II. The bottom l8 of the bowl is in substantially horizontal position, and the cutters 52 are functioning to cut a path or trough through which the lower extremity of the bowl may freely advance. The rear supporting wheels 21. are progressing along this path or groove well within the opposite sides thereof, and the front apron 23 is elevated so as to avoid obstruction to the dirt which enters the bowl. 3

.When the bowl of the scraper has been sufficiently loaded as indicated in Fig. 2, the front apron 23 may be lowered by operation of the hydraulic jack 24, to the position shown in Fig. 2. As the cutter 49 of the front apron 23 approaches the cutter blade i8of the dirt receiving bowl, the blade 48 cuts through the transverse hill or mound of dirt in front of the bowl, and. ultimately confines the load 82 in the manner clearly illustrated in Fig. 2. The loaded bowl may thereafter be quickly elevated away from the ground to the position shown in Fig. 3, by operation cf the hydraulic jack 28. hydraulic jack 28 causes the piston 54 thereof to move downwardly and to swing the rear end of the main frame l4 upwardly, and since the loaded bowl is rigidly attached to the arms l5 and cross beam ll of the mainv frame, the loaded bowl will naturally be withdrawn from the ground and elevated. If the springs 55' are utilized, these springs will naturally assist the jack 28 in elevating the loaded bowl, thereby minimizing the pressure required for. actuation of the jack 28, The loaded scraper assemblage may then be freely transported along the ground, to carry the load 52 to any desired place.

Should it become desirable to dump the load 82, this can readily be accomplished by merely manipulating the hydraulic jacks 24, 22to position the mechanism as shown in Fig. 4. The jack 24 should first be operated to raise the front apron 23, whereupon the rear jack 22 may be actuated so as to swing the levers 43 downwardly about their pivots 44. As the levers 43 are swung downwardly, the swinging end thereof being pivotally attached to the rear ends of the brackets 42, will cause the rear apron 2i to travel forwardly along the bowl bottom i8 and between the side walls 20. The flap 4| at the lower extremityof the rear apron 2| will then travel along the upper surface of the bowl bottom l8 and the entire load 82 will be pushed forwardly and delivered from within the bowl over the scraper blade l9. During this forward tavel of the apron 2|, it will assume different angular positions and when the final forward position of the apron has been reached, this apron will be inclined rearwardly and upwardly so as to permit final discharge of the load 52 by gravity. By virtue of the fact that the rollers 38 which support the apron 2| travel along the bowl bottom I8, and the rollers 48 engage Such operation of the sasement with the cross beam. i1

required to move the apron 2| forwardly is reduced to a minimum; and the apron Ii may obviously be returned to normal position in enby reverse operation of the Jack 22, thus placing the scraper assemblage in condition for subsequent reloading.

From the foregoing specific description, it .will be apparent that the present invention provides an improved scraper assemblage which can be readily manipulated, and which may be eflectively loaded and unloaded with minimum effort. The side flanges ll of the front apron 23 will effectively confine the load it within the scraper bowl, and if any dirt should succeed in passing the scraper flap ll, such dirt will fall through theopening II at the rear end of the bowl bottom l8, and will drop to the ground. The scrapor flap II is particularly advantageous when stick material is being handled, and will insure complete removal of all soil from within the scraper bowl. It is also important to note that the number of hydraulic Jacks required, is reduced to a minimum, there being but a single jack 22 for actuating the rear apron II, a second jack 24 for actuating the front apron It, and a third jack 2| for elevating and lowering the bowl. All of these jack mechanisms crestfectively protected against possible damage, and do not interfere with each other during normal operation of the scraper mechanisms. While the front and rear ends of the bowl are open,

these ends of the bowl are effectively enclosed by the aprons 2|, 23 to confine the load within the bowl, and the scraper assemblage can be loaded from the top without interference by the aprons and hydraulic jacks. The entire assemblage can obviously be constructed in a rigid manner and at minimum cost by utilizing welded plates to form the main frame H, the bowl, and the auxiliary frame 25, and the disposition of the transporting wheels for the structure is such that they will not in any manner interfere with the scraping, loading, and unloading operations.

Special attention is directed to the fact that our improved scraper assemblage is relatively simple, compact, and durable in construction, and can be conveniently manipulated with minimum power. Our improved scraper assemblage also has maximum capacity with minimum width, and thedirt confining bowl may obviously be made of considerable length in order to increase the capacity to a maximum. -The formation of the main frame I with the liquid confining reservoir ill therein and with the, liquid conducting pipes 31 disposed within the side beams II, also enable simplification of the assemblage and improvement in the appearance thereof, without sacrificing strength. The scraper blade I! and the cutter 49 may obviously be readily reversed or renewed, and all portions of the assemblage are inspection and repair.

It should be understood that it is not desired to limit this invention to the exact details of construction or to the precise mode of operation herein shown and described, for various modifications within the scope of the claims may occur to persons skilled in the art.

We claim:

1. In a scraper, a'transportable frame, a bowl rigidly suspended from said frame and having parallel flat side walls and a flat bottom connecting said walls to form a forwardly and rearwardly open assemblage, a rear apron movable conveniently accessible for within said bowl with varying angularity, porting rollers for said apron coacting with said bowl bottom, guiding rollers for said apron coacting with said side walls, and a scraper flap carried by said apron and constantly engaging .said bottom in advance of said rollers.

2. In a scraper, a transportable frame', a bowl suspended from said frame and having side walls interconnected by a bottom to provide an open ended trough shaped assemblage, a rear apron movable with varying angularitv within said bowl, supporting rollers for said apron coacting with said bowl bottom, and a scraper flap pivotally suspended from said apron and constantly engaging said bottom in advance of said rollers. 3. In a scraper, a transportable frame, a bowl suspended from said frame and having a flat bottom and side walls extending upwardly from said bottom, a rear apron movable within said bowl between said side walls, anti-friction supports for .said apron coacting with said bowl bottom, and a scraper flap carried by said apron and constantly engaging said bottom in advance of said supports, said bottom being formed to permit material in back of said flap to gravitate freely from within said bowl.

4. In a scraper, a transportable frame, a bowl suspended from the rear of said frame and having side walls interconnected at their lower ends by a flat bottom having a rear opening, a rear apron movable along said bottom and between said side walls, anti-friction means for supporting said apron upon said bottom and for guiding the same between said guide walls, a scrap'er flap carried by said apron and constantly engaging said bottom in advance of said anti-friction means and of said opening, and a front apron having side walls movable in close proximity to the inner surfaces of said bowl walls.

5. In a scraper, a transportable main frame pivotally supported at its front end and having a trough shaped bowl rigidly suspended from its rear end, an auxiliary frame having its forward end pivotally attached to the rear of said bowl and its rear end swingably supported by rear wheels, means for relatively swinging said frames to raise and lower said bowl, a rear apron supported to move along and within said bowl and having a rearwardly projecting bracket, a lever pivotally associated with the rear portions of said main frame and of said bracket, and jack means connecting said lever with the pivot portion of said auxiliary frame, said jack means being operable to move said apron with decreasing inclination relative tothe bowl bottom as said apron advances forwardly.

6. In a scraper, a transportable main frame pivotally supported at its front end and having a trough shaped bowl rigidly suspended from its rear end, an auxiliary frame having its forward end pivotallyattached to the rear of said bowl and its rear end swingably supported by rear wheels, means for relatively swinging said frames to raise and lower said bowl, a rear apron supported to move forwardly within said bowl and having a rearwardly projecting integral bracket, a lever pivotally associated with the rear portions of said main frame and of said bracket, and jack means connectin said lever with the rear lower portion of said bowl, said jack means being operable to advance said apron forwardly with diminishing inclination relative to the bottom of said bowl.

'7. In a scraper, a transportable main frame pivotally supported at its front end and having a said lever with the rear of said bowl and with the pivot portion of said auxiliary frame, said jack,- lever and bracket being formed to forwardly advancesaid apron with diminishing inclination relative to the bottom of said bowl.

8. In a scraper, a main frame having front supporting wheels and rearwardly extending rigid side arms rigidly interconnected at their rear ends by a transverse beam, a forwardly and rearwardly open bowl rigidly suspended from said arms, an auxiliary frame having its front end pivotally attached to the rear of said bowl and its'rear end swingably supported by rear supporting wheels, a hydraulic jack connecting the medial portion of said beam with the medial portion of said auxiliary frame to raise and lower said bowl, a rearapron movable along and, within said bowl and having an integral bracket extending rearwardly therefrom beneath said transverse beam, a lever pivotally connecting said main frame and the end of said bracket, and another hydraulic jack connecting the medial portion of said lever with the pivotal connection between said bowl and said auxiliary frame, said last mentioned jack being operable toadvance said apron with varying inclination relative to the bowl bottom.

9. In a scraper, amain frame having front supporting wheels and rearwardly extending rigid side arms rigidly interconnected at their rear end; by a transverse beam, a forwardly and rearwardly open bowl rigidly suspended from said arms, an auxiliary frame having its front end pivotally attached to the rear of said bowl and its rear end swingably supported by rear supporting wheels, a hydraulic jack connecting the medial portion of said beam with the medial portion of said auxiliary frame to raise and lower said bowl, a rear apron movable along and within said bowl and having an integral bracket extending rearwardly therefrom beneath said transverse beam, a lever pivotally connecting said main frame and the. end of said bracket, another hydraulic jack connecting the medial portion of said lever with the pivotal connection between said bowl and said auxiliary frame and being operable to advance said apron with varying inclination relative to the bowl bottom, a front apron cooperating with the forward portion of said bowl, and a third hydraulic jack pivotally connecting the forward portion of said main frame with said front apron.

10. In a scraper, a frame transportably supported by a wheel at the front end thereof and being swingable directly about the axis of said wheel, a bowl rigidly suspended from said frame and being swingable therewith about said wheel axis; said bowl having side walls and a bottom rigidly interconnecting said walls, an apron movable within said bowl and over said bottom with varying inclination relative to the load bearing surface of said bottom, said apron having a.

scraper flap movably suspended therefrom and constantly engaging said bottom surface during movement of the apron, and means for moving said apron along said bottom.

11. In a scraper, a frame transportably supported by a front wheel and being swingable directly about the wheel axis, a bowl suspended from said frame rearwardly of said wheel and being swingable with the frame about said wheel axis, said bowl having side walls and a bottom rigidly attached to said walls and said bottom having a front cutting edge, an apron movable back and forth between said walls and over said bottom with diminishing inclination relative to the load bearing surface of said bottom when moving toward said edge, said apron having a scraper flap pivotally suspended from its lower portion and constantly engaging said bottom surface during movement of the apron toward said cutting edge, and means for moving said apron along said bottom.

12. In a scraper, a transportable bowl having side walls and a bottom, an apron movable with varying angularity within said bowl between said side walls and over said bottom, supporting rollers for said apron coacting with said bowl bottom, a scraper flap movably suspended from said apron and constantly engaging said bottom in advance of said rollers, and means for moving said apron along said bottom.

13. In a scraper, a transportable bowl having parallel upwardly extending side walls and a bottom rigidly connecting said walls, an apron movable within said bowl with varying inclination relative to said bottom, supporting rollers for said apron coacting with said bowl bottom, a scraper flap carried by' said apron and constantly engaging said bowl bottom in advance of said rollers, antifriction means for guiding said apron along said side walls, and means for moving said apron alon said bottom.

14. In a scraper, a transportable frame, a bowl suspended from said frame and having laterally spaced side walls and a fiat bottom connecting the lower portions of said walls, a rear apron movable along said bowl between said walls, supporting rollers carried. by said apron and coacting with said bowl bottom, and means for moving said apron and said rollers along said bowl, said moving means cooperating with said apron remote from said rollers and being formed to cause said apron to swing about the axis of said rollers and to assume decreasin inclination relative to said bowl bottom as the apron moves forwardly.

15. In a scraper, a transportable frame, a bowl rigidly suspended from said frame and having a flat bottom provided with a front cutting blade, a rear apron carried by rollers coactingwith said bottom and being movable within said bowl to deliver material forwardly over said blade, and means for moving said apron and said rollers along said bowl, said moving means being formed and cooperating with said apron to cause the latter to swing about the roller axis and to assume decreasing inclination relative to said bowl bottom as the apron approaches said blade. I

16. In a scraper, a transportable frame, a bowl rigidly, suspended from said frame and having a flat bottom provided with a front cutting blade, a rear apron carried by rollers coacting with said bottom and being movable within said bowl to deliver material forwardly over said blade, means for moving said apron and said rollers along said bowl, said moving means being formed and cooperating with said apron to cause the latter to swing about the roller axis and to assume decreasing inclination relative to said bowl bottom as the apron approaches said blade, and a front apron cooperable with the front of said bowl and with said blade to confine material within me bowl. 17. In a scraper, a transportable frame, abowl suspended from-said frame and having a flat bottom provided with a front cutting blade, a rear apron pivotally supported upon and movable along'said bowl bottom and having a rigid rear projection, a lever pivotally suspended from said frame and pivotally attached to said apron proa iection, and means for moving said lever to cause said apron to simultaneously advance along said bowl and to assume decreasing inclination relative to said bottom as the apron approaches said blade.

18. In a scraper. a transportable bowl having a flat bottom and a front cutter. a rear apron having a lower supporting pivot movable along and in close proximity to said bottom, anti-friction means i for maintaining said pivot uniformly spaced from said bottom at all times. and means for moving said apron and its pivot along said bowl toward and away from said cutter, said movingmeanscooperatingwithsaid aprontoswing the same about said pivot and to asume decreasing inclination relative to said bowl bottom as the apron approaches said cutter.

19. Inascraper, aloadconflningbowlhavinga cutter andailat bottom extending away from said cutter, a load ejecting apron having a supporting pivot at its lower end movable along said bowl bottom, anti-friction means for maintaining said pivot uniformly spaced from said bottom at all times, and means for moving said apron to advance its pivot along said bowl, said moving means being formed to cause said apron to swing about said pivot and to assume decreasing inclination relative to said bottom as the apron approaches said cutter.

HERMAN C. FRENTZEL, Jl. HENRY C. FRENCH.

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