Title:
MULTI-ELEVATOR SCRAPER
United States Patent 3758966


Abstract:
A tractor drawn earth moving scraper having a cutting edge for guiding earth into the open forward end of a bowl is provided with a pair of side-by-side powered elevators disposed above the cutting edge to forcibly assist the movement of earth into the bowl. The elevators are fastened to the bowl by linkage which provides for independent rising and falling of each elevator in response to the volume and resistance of earth beneath each individual elevator. This construction increases earth handling efficiency, reduces the stress on elevator flights and facilitates transportation of very large scrapers. One elevator may be driven from the scraper tractor engine while the other elevator is driven from the rear wheel engine to make more efficient use of available power.



Inventors:
MILLER L
Application Number:
05/207388
Publication Date:
09/18/1973
Filing Date:
12/13/1971
Assignee:
CATERPILLAR TRACTOR CO,US
Primary Class:
Other Classes:
198/607
International Classes:
E02F3/64; (IPC1-7): B60P1/36
Field of Search:
37/4,8 198
View Patent Images:
US Patent References:
3646693IMPROVED ELEVATOR CONTROL FOR EARTH-MOVING APPARATUS1972-03-07Simmons
3512277CONTROL SYSTEM FOR TWO-ENGINE VEHICLE1970-05-19Stuller
3296715Self-loading scraper1967-01-10Jass et al.
2874824Flexible fin draper1959-02-24Sund
2791044Dirt handling apparatus1957-05-07Hancock
2709011Tractor mounted loading apparatus1955-05-24Radin et al.
2684752Conveyer for corn cutting machines1954-07-27Schultz
2017477Excavator and loader1935-10-15Shippee
1974668Automatic loader1934-09-25Souter
1829198Delivery mechanism for snowplows1931-10-27Speer
1780299Shock loading and unloading machine1930-11-04Jackson



Primary Examiner:
Pulfrey, Robert E.
Assistant Examiner:
Eickholt, Eugene H.
Claims:
What is claimed is

1. A scraper having bowl means with a cutting edge at the lower forward end thereof further comprising a plurality of powered elevators disposed above said cutting edge in side-by-side relationship and being coupled to said bowl by means providing for rising and falling, relative to said cutting edge, of each elevator independently of rising and falling motions of the others thereof.

2. The combination defined in claim 1 wherein each of said elevators is coupled to said bowl means through a pair of upper links each having one end pivotally coupled to said elevator and an opposite end pivotally coupled to said bowl means, and by a pair of lower links each having one end pivotally coupled to said elevator and an opposite end pivotally coupled to said bowl means, said upper and lower links of each of said elevators being pivotal relative to said elevators and relative to said bowl independently of pivoting motion of said links of the others of said elevators.

3. A scraper having bowl means with a cutting edge at the lower forward end thereof further comprising a plurality of powered elevators disposed above said cutting edge in side-by-side relationship and being coupled to said bowl by means providing for rising and falling of each elevator independently of the others thereof,

4. The combination defined in claim 1 wherein said scraper has front wheels and an engine for driving said front wheels and further has back wheels and a separate engine for driving said back wheels further comprising first and second hydraulic motors operatively disposed on first and second ones of said elevators, said first motor driving said first elevator and said second motor independently driving said second elevator, first pump means driven by said front wheel engine for supplying driving fluid to a first of said hydraulic motors and second pump means driven by said rear wheel engine for supplying hydraulic fluid to the second of said motors.

5. The combination defined in claim 1 wherein said plurality of powered elevators comprises two elevators disposed in side-by-side relationship above said cutting edge of said bowl.

6. A scraper comprising:

Description:
BACKGROUND OF THE INVENTION

This invention relates to scrapers for cutting and moving earth or the like and more particularly to self loading scrapers of the form having elevators for assisting loading operations.

A variety of self contained loading assist mechanisms have been employed on scrapers which otherwise may require the use of pusher tractors to assure complete loading. One of the most commonly used loading assist mechanisms is a chain and flight elevator situated at the forward portion of the bowl over the cutting edge to force earth backward and upward into the bowl. Such elevators are generally attached to the bowl through pivotal linkage which enables the elevator to rise and drop as necessary to accommodate to differences in the amount and resistance of material passing over the cutting edge.

Elevators of this kind are less effective if the bowl is made longer for the purpose of increasing scraper capacity. Increasing the height of the bowl for this purpose has the disadvantage of creating an undesirable top heaviness and consequent instability of the vehicle as a whole. Increasing the width of the bowl for a similar purpose tends to aggravate certain disadvantages of the conventional elevator configuration.

Among these disadvantages of the conventional elevator structure is the fact that the entire elevator rises as a unit when a mound of earth or boulder or other concentration of material crosses the cutting edge at only one particular portion of the edge. Under that condition, the elevator may not function efficiently to move earth across the other portions of the cutting edge. There may in fact be some loss of material which must then be reloaded.

Further, elevator flights are supported only at the ends and thus are subjected to considerable bending stress. If made broader to accommodate to a wider bowl, then the flights and certain other elevator components as well must be made more massive and heavy.

Further, the conventional elevator is necessarily a sizeable component of the scraper and adds considerably to the overall weight thereof. If made wider, this massiveness and weight contributes appreciably to problems in disassembly for transporting the scraper over long distances and in reassembling the scraper at the work site.

Still further, the elevator is often powered by a hydraulic motor which receives driving fluid from pumps operated by the engine or engines which drive the wheels of the scraper. In scrapers where separate engines are used to drive the front and rear wheels, it has been desirable to drive the elevator with fluid from two pumps, each operated by a separate one of the engines in order to avoid an excessive diversion of available power from one set of wheels. This requires considerable hydraulic circuit complication to assure that the same amount of fluid is returned to each pump as is received therefrom.

SUMMARY OF THE INVENTION

This invention relieves the problems discussed above by providing two or more side-by-side elevators at the forward portion of the bowl of the scraper. Each elevator is separately attached to the bowl so that each may rise and fall in response to variable loading independently of such motion of the other. Elevator flights are less lengthy than would be required for a single elevator in a bowl of comparable breadth and transport and assembly of the scraper is greatly facilitated. In a preferred form of the invention, the multiple elevators may be driven by different ones of the plurality of engines which are present on many scraper designs.

Accordingly, it is an object of this invention to increase the efficiency of scrapers of the form employing powered elevators to assist loading operations.

It is another object of this invention to provide for more continuous and complete engagement of the elevator means of an elevating scraper with material passing over the cutting edge thereof where different amounts of material may pass over different portions of the cutting edge at certain times.

It is another object of the invention to reduce the bending stresses upon the flights of an elevator means of a scraper and to facilitate disassembly, transportation and reassembly of components of an elevating scraper.

The invention, together with further objects and advantages thereof, will best be understood by reference to the following description of a preferred embodiment taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a side elevation view of an elevating scraper embodying the invention;

FIG. 2 is a perspective view of the bowl and elevator means of the scraper of FIG. 1 further illustrating the structure thereof;

FIG. 3 is a section view taken along lines III--III of FIG. 2 further clarifying the structure of means for attaching the elevator to the bowl of the scraper; and,

FIG. 4 is a schematic diagram showing suitable fluid circuit means for driving the elevators of the scraper of FIGS. 1 to 3.

DESCRIPTION OF A PREFERRED EMBODIMENT

Referring initially to FIG. 1 of the drawings, a scraper 11 embodying the present invention may be of essentially conventional construction except for the elevator means 12 and certain associated components as will hereinafter be described although the invention enables the use of a broader scraper construction than has heretofore been customary. Thus such a scraper 11 may typically include a bowl 13 supported at the back end by frame means 14 riding on rear wheels 16 driven by a rear engine 17. A two wheeled tractor 18 driven by a forward engine 19 supports the bowl 13 at the forward end through a goose neck 21 and draft arms 22 which are pivoted to the central region of the bowl sidewalls. Hydraulic jacks 23 are connected between goose neck 21 and the upper forward portion of the bowl 13 to provide for raising and lowering of the forward end of the bowl by pivoting motion about the axis of the rear wheels 16. The rear wall of bowl 13 is defined by an upright ejector plate 24 which may be advanced by operation of a hydraulic jack 26 to discharge material from the bowl. Suitable detailed constructions for the bowl 13, and support and traction means described above are well known to the art.

Referring now to FIGS. 1 and 2 in conjunction, the bowl 13 in this example of the invention has sidewalls 27 and a floor 28 with the rear wall being defined by the movable ejector plate 24 as previously described. The bowl 13 in this example is of the known form which carries an auxiliary bowl 29 at the lower forward end. Auxiliary bowl 29 is provided with a floor 31 which forms a forward extension of the main bowl floor 28 and has upwardly extending sidemembers 32 at each side which are pivoted to the sidewalls 27 of the main bowl by pivot means 33 whereby the auxiliary bowl 29 may be swung upward and forward by suitable hydraulic jacks 34 to provide an opening between floors 31 and 28 through which material may be ejected by advancement of ejector 24. Elevator means 12 is swung upward with the auxiliary bowl 29 by means which will be hereinafter described.

A cutting blade 36 extends forward and downward from the front edge of auxiliary bowl floor 31 to intercept a surface layer of earth when the bowl 13 is lowered to perform a loading operation. A striker plate 37 extends forward and downward from the forward edge of main bowl floor 28 to smooth deposited earth during the ejection operation.

Considering now the structure of the elevator means 12, with reference to FIG. 2 in particular, a pair of chain and flight elevators, including left elevator 41a and right elevator 41b are situated at the front end of bowl 27 above cutting edge 36 in side-by-side relationship. Each such elevator 41 in this example has a rectangular frame comprised of side members 43 joined by spaced apart cross members 44 including tubular cross members 46 and 47 at the top and bottom respectively. A sprocket gear 48 is mounted on an axle 49 extending through each tubular cross member 46 and 47 at each end thereof. Endless chains 51 extend along each side of each elevator 41a and 41b and each is engaged on the sprocket gears 48 at the top and bottom of that side of the elevator. To manipulate earth, linear flights 52 defined by angle members extend between the chains 51 of each elevator at spaced apart intervals along the chain whereby movement of the chains by rotation of the upper sprocket gears 48 causes the flights 52 to sweep above the cutting edge 36 and forcibly draw material back into the bowl 27. At the front of the elevators 41a and 41b chains 51 are supported at intervals between the associated sprocket gears 48 by idler wheels 53 mounted on brackets 54 which project a small distance forwardly from frame side members 43.

A rotary hydraulic motor 56 is mounted at the top outside corner of each elevator 41a and 41b in coaxial relation to the top axle 49 of the associated elevator and in driving relation thereto. Thus the hydraulic motors 56 drive sprocket gears 48 at the top of each elevator and thereby cause the elevator flights 52 to sweep downward at the front of the elevators and then circularly above the cutting edge 36 and back up at the rear of the elevator in a continuous motion. A hydraulic circuit for driving the motors 56 in an optimized manner will be hereinafter described.

To function efficiently elevators of this kind must be able to rise and fall relative to the cutting edge 36 to accommodate to different volumes of material which may be entering the bowl. For this purpose, each elevator 41a and 41b is attached to the bowl 27 through linkage which includes a pair of lower links 57 and a pair of upper links 58. At each elevator, one of the lower links 57 is pivotally coupled to an extension 47' of lower tubular cross member 47 and extends in a generally backward and upward direction with the back end being pivotally coupled to sidewall 32 of auxiliary bowl 29. The other lower link 57 of each elevator is pivotally coupled to the opposite end of lower tubular cross member 47 and extends backward and upward in a similar direction with the back end being pivotally coupled to a support bracket 59 that extends upward from the center of floor 31 of the auxiliary bowl. Referring now to FIG. 3 in conjunction with FIG. 2, the upper links 58 of each elevator 41a and 41b have back ends pivoted to a separate one of the side members 43 of the associated elevator frame and each such link extends forward and upward therefrom and has a front end pivoted to a bracket 61 mounted on a crossbar 62 which extends between the upper front ends of bowl sidewalls 27 in front of the elevators. Downward motion of the two elevators 41a and 41b, which might otherwise cause abutment of the elevator flights against cutting edge 36, is limited by contact of the frame cross member extensions 47' against forwardly extending shelves 63 formed in the forward edge of sidewalls 32 of auxiliary bowl 29. In this connection, it should be observed that this abutment of extensions 47' against shelves 63 serves to lift the elevators upward when the auxiliary bowl is raised for the purpose of ejecting material as previously described.

Thus the two elevators 41a and 41b have a normal rest position at which the lower ends of the elevators are in close proximity to the cutting edge 36 while the upper portions of the elevators extend backward and upward within bowl 13. At this position, the elevator flights 52 dig into material entering the bowl 13 over cutting edge 36 and forcibly assist the movement of such material back into the bowl. Owing to the suspension of the elevators by means of the upper and lower links 57 and 58 the elevators may rise if the volume or resistance of the material increases. In contrast to prior elevator scrapers, any such rise does not require that the entire elevator means 12 be raised if the increased concentration of material is confined to only one portion of the cutting edge 36. Thus one elevator may rise in response to such a concentration while the other elevator remains lower in efficient operating position with respect to material passing over the subjacent section of the cutting edge. Thus a more efficient loading action is realized. Moreover, if the elevator means 12 must be detached from the bowl 13 as is customary in transporting scrapers over long distances, such disassembly, transport and the subsequent reassembly at another work site is greatly facilitated because of the reduced size of the individual elevators 41a and 41b relative to a single broad elevator. Still further, the flights 52 have only one half the length of the corresponding flights of a single broad elevator and thus bending stresses on the flights are substantially reduced.

The hydraulic motors 56 of both elevators may be driven with fluid supplied from a pump driven by the engine or engines which propel the scraper in the conventional manner if desired, however the use of a plurality of elevators enables a unique fluid circuit to be employed which makes efficient use of the power available on a scraper of the form which has separate engines for powering the front and rear wheels. Referring now to FIG. 4, most scrapers of the kind which have both a front wheel engine 19 and rear wheel engine 17 are also provided with a source of fluid under pressure driven by such engines. Typically this may consist of a pump 66 driven by the front engine 19 which delivers fluid from a tank 67 to an outlet conduit 68. To establish a maximum constant pressure in outlet conduit 68 a relief valve 69 is connected between conduit 68 and tank 67. Similarly, a pump 71 is driven by rear engine 17 and delivers fluid from a tank 72 to an outlet conduit 73, a relief valve 74 being connected between conduit 73 and tank 72 to establish an upper pressure limit.

In accordance with the present invention the output of the pump 66 which is driven by front motor 19 is utilized to operate elevator 41a while the output of the pump 71 driven by the rear engine 17 is used to power elevator 41b. For this purpose pump output 68 connects with the inlet of a first pilot operated control valve 76 which has an outlet connected to the fluid inlet of motor 56 through a conduit 77. Valve 76 has a normal position at which conduit 77 is blocked from pump outlet 68 thereby inactivating motor 56 while pump outlet 68 is communicated with tank 67 through a drain outlet 78 to return fluid from the pump directly to the tank. Upon the application of a fluid pressure signal to the pilot means 79 of control valve 76 the valve shifts to communicate pump outlet 68 with conduit 77 thereby energizing motor 66 and driving elevator 41a. A conduit 81 returns discharge fluid from motor 56 to the tank 67.

Similarly, the outlet 73 of pump 71 connects with a second control valve 82 which has an outlet conduit 83 communicating with the driving fluid intake of motor 56 of the left elevator 41b. Control valve 82 has a normal position at which pump outlet conduit 73 is communicated with a return line 84 to tank 72 while conduit 83 is blocked to inactivate motor 56. Upon application of a fluid pressure signal to pilot means 86 of control valve 82, the valve shifts to transmit fluid from pump 71 to motor 56 to actuate elevator 41b. Discharge fluid from motor 56 of elevator 41b is returned to tank 72 through a discharge conduit 87.

To operate control valves 76 and 82 and thereby control the elevators 41, a manually operated valve 88 is situated at the operator's station on the scraper and has an outlet conduit 89 for communicating with the pilot means 79 and 86 of the control valves 76 and 82 respectively. Manual valve 88 receives fluid from a tank 91 through an additional pump 92. To establish an upper pressure limit for fluid transmitted through the manual valve 88, an additional relief valve 93 is connected between the outlet of pump 92 and tank 91. The additional pump 92, which may be driven by front engine 19, is utilized rather than drawing fluid from pump 66 since it is then unnecessary that the lengthy pilot signal lines extending from manual valve 88 to the control valves 76 and 82 be of the bulky and expensive form needed to transmit high pressure. Manual control valve 88 has an unoperated position at which the output of pump 92 is blocked from pilot signal conduit 89 but is returned to tank 91 through a return line 94. Thus at the unoperated position of manual valve 88 control valves 76 and 82 are also unoperated and therefore the hydraulic motors 56 are inactive. Manual valve 88 has an operated position at which the output of pump 92 is transmitted to pilot signal line 89 thereby causing control valves 76 and 82 to be operated to initiate operation of motors 56 and thus elevators 41.

While the invention has been described with respect to a single exemplary embodiment, it will be apparent that many modifications are possible and it is not intended to limit the invention except as defined in the following claims.