US3452458A

US3452458A - Self-loading scraper with elevator mounting coupled to ejection means

Info

Publication number: US3452458A
Application number: US563403A
Authority: US
Inventors: Trevor G Campbell; Robert W Lichti; Richard K Liess
Original assignee: Caterpillar Tractor Co
Current assignee: Caterpillar Inc
Priority date: 1966-07-07
Filing date: 1966-07-07
Publication date: 1969-07-01
Anticipated expiration: 1986-07-01
Also published as: DE1634752A1; GB1156748A

Description

July 1, 1969 T. G. CAMPBELL ET AL 3,452,458

SELP-LOADING SCRAPER WITH ELEVATOR MOUNTING COUPLED TO EJECTION MEANS Filed July 7. 1966 of 4 Sheet u 5 H T.PHSP m rm VAUL T We .M m 6 7 RMR wam as Rom TRR @M f July 1, 1969 T. G. CAMPBELL ET AL 3,452,458

SELF-LOADING SCRAPER WITH ELEVATOR MOUNTING COUPLED TO EJECTION MEANS Filed July 7, 1966 Sheet 2 of -4 INVENTORS. TREVOR G. CAMPBELL ROBERT W. L\ ;HT\ RlCHARD K. mass y ,969 T. e. CAMPBELL- ET AL 3,452,458" TOR MOUNTING ANS SELF-LOADING SCRAPER WITH ELEVA COUPLED TO EJECTION ME Filed July 7. 1966 INVENTORS. TREVOR Cw. CAMPBELL ROBERT W. L \C,HT\ R\C.HARD K. \F 5S BY Q JW #Pkfi? ATTORNE July 1, 1969 T G, CAMPBELL SELF-LOADING SCRAPER WITH ELEVATOR MOUNTING COUPLED TO EJECTION Filed July '7. 1966 ET AL 3,452,458

MEANS Sheet of 4 INVENTORS- TREVOR G. CAMPBELL ROBERT'W. L\C.HT\ R\c.HARD K. mass ATTORNEY U.S. Cl. 37-8 6 Claims ABSTRACT OF THE DISCLOSURE A scraper has a chain and flight elevator for assisting the movement of earth or the like into a load carrying bowl. The elevator is supported by four pivot arms which provide for movement of the elevator to adjust to varying depths of cut and to override obstacles with the mechanism being arranged for movement of the lower end of the elevator along a path approximately coincident with the soil failure plane. To avoid wedging of earth against the elevator during ejection, the upper pivot arms connect to the load ejector of the scraper whereby the upper end of the elevator is moved forward and upward automatically upon operation of the ejector.

This invention relates to tractor drawn earthmoving scrapers and more particularly to elevator mounting structure for scrapers of the self-loading class.

Tractor drawn scrapers of the type having a soil cutting blade at the lower forward edge of a load carrying bowl may be provided with a continuous chain conveyor extending upwardly from the blade and forming the front boundary of the bowl. The elevator functions to lift soil from the region of the blade and thereby reduces the resistance which the load offers to the movement of additional soil into the bowl. This usually eliminates any need for using a separate pusher tractor with the scraper in order to fully load the bowl.

If the elevator is rigidly mounted on the scraper, excessive stalling and other problems occur. It has therefore been the practice to provide a floating mounting in which the elevator is attached to the scraper by a series of pivot arms. In these systems the elevator can rise to override large stones and other obstructions and can adjust itself to variations in the depth of cut. However, the floating elevator mountings heretofore employed in the art have not been fully satisfactory in that several serious operational problems are encountered.

A first difiiculty occurs in connection with the unloading or ejection of the contents of the bowl. In selfloading scrapers ejection may be accomplished by pivoting the base of the bowl backwardly and upwardly or by mechanism which has an essentially similar effect. It has been found that this pivoting tends to wedge the contents of the bowl against the elevator thereby interfering with the ejection process and with the action of the elevator itself. Prior forms of floating elevator mounting do not pivot in a manner which will avoid these effects. The practical consequences may include a reduction in the payload which can be carried by as much as twenty-five percent.

Further problems with the packing of earth in conventional floating mountings occur around the extreme lower end of the elevator where the supporting pivot arms connect thereto.

A serious source of inefliciency in conventional floating elevator mountings arises from the particular path followed by the lower end of the elevator in its pivoting movement. This motion has not provided for maintaining nited States Fatent O an optimum relationship between the position of the lower end of the elevator and the undisturbed soil surface ahead of the blade. If the elevator pivots in a generally upward direction there is a tendency for soil to be bulldozed ahead of the elevator. If, on the other hand, the elevator pivots too far forwardly, undisturbed soil will be contacted by the elevator flights with consequent jumping and loss of elevator action.

A further problem occurs in connection with providing an adequate holddown force for resisting upward pivoting of the elevator. To avoid excessive jumping and to minimize contact with stops it is desirable that the holddown force become progressively greater as the elevator pivots upwardly. While this requirement has been generally recognized, prior mountings have not necessarily pro vided such an effect as an inherent property of the mecha nism and in some cases it has been necessary to add springs or other complications to provide for such a result.

The present invention is a floating mounting which meets the several problems and requirements discussed above. In particular the elevator is connected to the scraper through four pivot arms in an arrangement through which the upper end of the elevator is pivoted forwardly during ejection to avoid wedging of the contents of the bowl and in which the lower end of the elevator may pivot upwardly along a path fairly closely coincident with the soil failure plane and against a constantly increasing holddown force inherent in the geometry of the pivot structure.

Accordingly it is an object of this invention to provide a floating mounting for the elevator of a self-loading scraper which allows an optimum adjustment of the elevator position to the various operations of the scraper.

It is another object of the invention to provide an elevator mounting structure for a self-loading scraper which avoids wedging of the contents of the scraper bowl during ejection.

It is a further object of the invention to provide a self-adjusting elevator for a scraper which maintains a preferred relationship to the soil surface.

It is still a further object of this invention to provide an elevator supporting structure for a self-loading scraper having a configuration which inherently produces a prO- gressively increasing holddown force resisting upward movement of the elevator.

The invention, together with further objects and advantages thereof, will best be understood by reference to the following specification together with the accompanying drawings, of which:

FIGURE 1 is a side elevation view, partially in section, of a tractor-drawn self-loading scraper having the elevator mounting structure of the present invention thereon;

FIGURE 2 is a side elevation view, partially in section, of the bowl region of the scraper of FIGURE 1 illustrating movement of the upper end of the elevator thereof in the course of ejection of the contents of the bowl;

FIGURE 3 is an additional side elevation view, partially in section, of the bowl region of the scraper illustrating the movement of the elevator thereof in response to variations in the depth of cut, obstacles and the like;

FIGURE 4 is a side elevation view of the lower end of the elevator and associated structure illustrating the position of the elevator relative to the soil surface at a first depth of cut; and

FIGURE 5 is a side elevation view of the lower end of the elevator and associated structure illustrating the changed position of the elevator relative to the soil surface at a depth of cut greater than that of FIGURE 4.

Referring now to the drawing and particularly to FIGURE 1 thereof, the scraper 12 has a bowl assembly 13 mounted on a pair of rear wheels 14 by a frame 16.

The scraper 12 is drawn by a two-wheel tractor 17 through a pair of draft arms 18 which extend along opposite sides of the bowl 13 and are coupled thereto by pivots 19. The forward ends of the draft arms 18 attach to a transverse spreader 21 which is coupled to tractor 17 by a gooseneck 22 and swivel hitch 23.

The bowl assembly 13 is formed in part by sidewalls 24 and an arcuate rearwall 26 and may be raised or lowered by operation of a hydraulic jack 27 connected between the spreader 21 and the forward portion of frame 16 and which is controlled from the operators ompartment of the tractor 17. The lifting and lowering of the bowl 13, through a pivoting movement about the axis of the rear wheels 14, may be for the purpose of adjusting the depth of cut or for raising the bowl to transport a load.

A cutting blade 28 is disposed along the lower forward edge of the bowl 13 and projects forwardly and downwardly therefrom to cut away a layer of the soil surface 29 and to guide the soil into bowl 13.

The base of the bowl 13 is formed by a pivoting platform 31 which in its lower position bridges the gap between the cutting blade support 32 and the lower edge of the bowl rearwall 26. Triangular side plates 33, having reinforcing structural members 34 along the edges thereof, extend upwardly from platform 31 to pivots 36 which couple the platform to the bowl sidewalls 24 and which are situated at the center of curvature of the rearwall 26. Thus platform 31 may be pivoted backward and upward, as indicated by dashed line 31' in FIGURE 2, to eject the contents of the bowl 13 through the bottom thereof.

To effect the pivoting movement of platform 31, with reference again to FIGURE 1, a lever 37 has an upper end pivoted to frame 16 behind the bowl 13 and has a lower end which is angled forwardly to extend under the rear portion of the bowl. A straight link 38 connects a pivot 39 at the lower end of lever 37 with a pivot 41 at the underside of platform 31 near the forward edge thereof. A pair of hydraulic jacks 42 are pivotably connected to an intermediate point on the lever 37 and to the frame 16 rearwardly therefrom. Thus ejection of the load from bowl 13 is accomplished by contracting the jacks 42 thereby pivoting platform 31 backward and upward as previously described.

In self-loading scrapers of this general class, the movement of soil from blade 28 into bowl 13 is assisted by an elevator 43 which has a lower end situated above the blade 28 and slightly forward therefrom. The elevator 43 extends up from the blade 28 and is inclined rearwardly in effect forming the forward boundary of the bowl 13.

Elevator 43 may be of the type having a frame 44 with a pair of spaced apart sprocket gears 46 journaled at the top thereof and a pair of idlers 47 at the lower end. An endless chain 48 is engaged on each pair of sprockets 46 and idlers 47 at each side of the frame 44 and carry transverse flights 49. Idler rollers 51 are mounted on the side rails of frame 44 at spaced apart points therealong to support the intermediate portions of the chains 48. To drive the elevator 43, a hydraulic motor 52 is coupled to the upper sprocket gears 46.

Considering now the floating mounting for the elevator 43 through which the hereinbefore identified advantages of the invention are realized, a pair of upper support arms 53 are disposed one at each side of the elevator with the forward ends of the arms being coupled to the elevator frame 44 by pivot joints 54. Arms 53 extend rearwardly and downwardly from pivots 54 and connect, by means of ball and socket joints 56, with projections 57 of the side plates 33 of bowl platform 31. Projections 57 extend a short distance upward from the platform pivots 36 so that pivoting motion of the platform 31 is transmitted to the upper end of the elevator 43 through the upper support arms 53.

As best illustrated in FIGURE 2, upward pivoting of the bowl platform 31 to the ejection position 31' is thus accompanied by a forward pivoting of the upper end of elevator 43 as indicatd at 43. Wedging of the contents of the bowl 13 against the elevator 43 is thereby alleviated and the ejection operation may be accomplished without delays or other difficulties.

A pair of lower support arms 58 are disposed on opposite sides of the elevator 43 with the forward ends of the arms pivotably coupled to the lower portion of the elevator frame 44 by ball and socket joints 59. The joints 59 may be situated at the extreme lower end of the elevator 43, at the axis of the lower idlers 47, with advantageous action insofar as the pivoting of the elevator is concerned. However, it has been found that problems with the packing of material around the arms 58 are alleviated by locating the joints 59 a short distance upward from the lower ends of the frame as in the present embodiment.

With the elevator 43 in its lowermost position relative to blade 28, the lower support arms 58 extend rearwardly and upward from joints 59 to pivots 61 which couple the rearward ends of the arms to the walls 24 of the bowl 13. To limit pivoting movement of the lower end of the elevator 43, an annular stop 62 is secured to each wall 24 of the bowl 13 in coaxial relationship to the pivot 61 thereat. Each such stop 62 has a first raised surface 63 against which a finger 64 on the end of arm 58 abuts to limit downward pivoting of the arm. Finger 64 contacts a second raised surface 66 on the stop 62 to limit upward movement of the arm.

In operation, the above-described structure permits the lower end of the elevator to pivot up and forward to override obstacles and to adjust to varying depths of cut and varying soil textures as shown in FIGURE 3. Considering now an important feature of the invention, it has been found that much more eflicient operation is obtained if the pivoting movement of the lower end of the elevator is arranged to follow as closely as possible along the failure plane of the soil immediately below the elevator. This requires that the lower end of the elevator 43 move forward as it rises. Such motion results primarily from the fact that the lower elevator support arms 58 extend downward as well as forward when the elevator is at its lowest position.

Referring now to FIGURE 4, the soil failure plane, which is the slanting surface 67 ahead of cutting blade 28 that defines the boundary between disturbed and undisturbed soil, has an inclination with respect to the soil surface 29 which varies according to soil texture and other factors. The inclination of the failure plane 67 will vary from about 15 to about 45 with 35 being typical. Thus it is not possible to design a fixed system in which the lower end of elevator 43 will follow exactly along the failure plane 67 under all conditions. However, by arranging the support arms 53 and S8 to provide for an upward and forward pivoting motion of the lower end of elevator 43 that follows reasonably closely along the normal soil failure plane 67, as illustrated in FIG- URE 5, the advantage of preventing bulldozing of soil ahead of the elevator while permitting a maximum amount of soil to be moved thereby is largely realized.

A further result of the above-described elevator support structure is that the downward force acting on the elevator 43 increases as the elevator pivots upwardly thereby minimizing hopping of the elevator over obstacles and minimizing contact against stops. The intersection of the axes of the

support arms

53 and 58 may be taken as the instantaneous center of the system and as this center moves rearwardly as the lower end of the elevator pivots up, the gravity force tending to hold the elevator down increases.

What is claimed is:

1. In a self-loading earthmoving scraper of the class having a scraper body with a bowl and a cutting blade at the lower forward end of said bowl and having an ejection member at said bowl which moves between a first and a second position to release the contents thereof wherein said ejection member has a portion which moves forwardly relative to said blade during the discharge of material, said scraper further having an elevator at the forward portion of said bowl above said blade, an elevator mounting comprising a coupling pivotably connecting said elevator to said forwardly moving portion of said ejection member for movement therewith whereby at least the upper end of said elevator is shifted forward by said movement of said ejection member to facilitate said release of the contents of said bowl.

2. An elevator mounting for a self loading scraper as defined in claim 1 wherein said coupling comprises at least one arm extending between said ejection member and said elevator, said arm being pivotably coupled to said ejection member.

3. An elevator mounting for a self loading scraper as defined in claim 1 wherein said ejection member forms at least a portion of the floor of said bowl and pivots to release material through the bottom thereof and wherein said coupling comprises a pair of arms disposed one at each side of said elevator and pivotably connecting said elevator with said ejection member for shifting said elevator forwardly upon movement of said member from said first to said second position thereof.

4. An elevator mounting for a self-loading scraper as defined in claim 1 wherein said ejection member forms at least a portion of the floor of said bowl and pivots upward and rearward from said blade to release said contents of said bowl through the bottom thereof behind said blade, said ejection member being provided with projections which extend above the pivot axis thereof, and wherein said coupling comprises a pair of arms extending between said projections and said elevator and being pivotably coupled to said projections at points thereon which are above said pivot axis.

5. An elevator mounting for a self-loading scraper as defined in claim 1 wherein said coupling comprises a pair of upper arms extending between the upper portion of said elevator and said ejection member and being pivotably connected to each thereof, and comprising the further combination of a pair of lower arms extending between said scraper body and the lower portion of said elevator and being pivotably connected to each thereof, said lower arms being positioned to pivot the lower end of said elevator upward and forward along a path which is substantially coincident with the normal soil failure plane above said cutting blade, and stop means limiting downward pivoting of said elevator at a position at which said lower arms are directed forwardly and downwardly from said scraper body towards said elevator.

6. An elevator mounting for a self-loading scraper as defined in claim 1 and comprising the further combination of a pair of lower arms extending between said scraper body and the lower portion of said elevator and being pivotably connected to each thereof, and wherein said coupling comprises a pair of upper arms extending between said ejection member at said bowl and the upper portion of said elevator and being pivotably coupled to each thereof, said upper arms being connected to said portion of said ejection member which moves forwardly relative to the scraper body as said member moves from said first to said second position thereof.

References Cited UNITED STATES PATENTS 2,791,041 5/1957 Hancock 378 3,090,139 5/1963 Hancock 378 3,331,149 7/1967 Rapp 378 3,210,868 10/1965 Liess 37-8 ROBERT E. PULFR'EY, Primary Examiner. EUGENE H. EICKHOLT, Assistant Examiner.

US. Cl. X.R. 37-126