US3077681A

US3077681A - Large capacity earthmoving scraper

Info

Publication number: US3077681A
Application number: US65698A
Authority: US
Inventors: Robert A Peterson
Original assignee: Caterpillar Tractor Co
Current assignee: Caterpillar Inc
Priority date: 1960-10-28
Filing date: 1960-10-28
Publication date: 1963-02-19
Anticipated expiration: 1980-02-19
Also published as: GB920403A; DE1484623A1

Description

Feb. 19, 1963 R. A. PETERSON LARGE CAPACITY EARTHMOVING SCRAPER 2 Sheets-Sheet 1 Filed Oct. 28, 1960 INVENTOR.

BY RoBe-rl; A. Peterson ATTORNEYS Feb. 19, .1963 R. A. PETERSON LARGE CAPACITY EARTI-IMOVING SCRAPER 2 Sheets-Sheet 2 Filed 001;. 28, 1960 INV EN TOR.

Arranuzys UQRUMWW JRQQ 3,077,681 LARGE CAPAQHTY EARTHMUVENG SQRAPER Robert Peterson, San Leandro, Calif., assignor to Caterpillar Tractor (30., Peoria, Rh, a corporation of California Filed Get. 28, race, fz'er. No. 65,698 3 Claims. (Cl. 31-429) This invention relates to earthmoving scrapers and particularly to a scraper capable of carrying an unusually large load and having means to facilitate the loading of a large quantity of earth into its bowl.

There are practical limits to the size of earthmoving scrapers of conventional design which have tended to discourage production of extra large capacity scrapers. Bowl width is limited by shipping requirements and structural strength. Increasing the height or length of the bowl so increases the power requirement for loading as to be uneconomical. It has long been recognized that the effort of loading a scraper bowl is largely spent on moving the earth already in the bowl when it is partially loaded to make space to accommodate the balance of the load as it enters. The friction of the earth against the walls of the bowl causes the expenditure of great effort particularly during the last part of the loading operation. Efforts have been made to increase the scraper bowl sizes by providing collapsible or telescoping type bowls and providing a small bowl slidable within a large bowl. It has been intended with such devices to make possible first the loading of the small bowl and then moving it rearwardly in the large bowl while the final part of the load was entering and thus avoid much of the frictional resistance to loading. These efforts have proven impractical because of high construction costs and high power requirements often necessitated for manipulation of the small bowl.

The present invention is applied to a so-called cable actuated scraper in which the apron is lifted and the injector moved forwardly by a cable wound upon a drum and powered by a winch. The apron is lowered or closed by gravity and the ejector is returned by spring force.

It is the object of the present invention to provide a large capacity scraper wherein a minimum of extra power is required for loading and wherein a particular existing sequence of apron and ejector operation is put to advantage in making a large scraper of unusually simple design and low cost.

Further and more specific objects and advantages of the invention and the manner in which it is carried into practice are made apparent in the following specification wherein reference is made to the accompanying drawings.

In the drawings:

FIG. 1 is a schematic view in side elevation and partially in section of a scraper embodying the present invention;

FIG. 2 is an enlarged fragmentary section taken on the line ll1l of F G. l and illustrating a part of the construction shown in FIG. 1; and

FIG. 3 is a schematic diagram illustrating the manner in which cables are employed to obtain a sequence of apron and e ector operation on the scraper of the kind shown in HS. 1.

The scraper schematically illustrated in FIG. 1 comprises a long bowl 1t) having a bottom 11 and side walls, one of which is shown at 12. It is supported at its rear as by a pair of wheels 13 and has pivotal connections, one of which is indicated at i l with draft arms 15 supported at their forward ends by a tubular cross member 15 which forms a part of a draft assembly partially shown connected with a tractor in a conventional manner. The scraper bowl has a cutting edge 17 adjacent its forward open end adapted to be lowered into cutting position with respect to the ground. A pivoted apron 18 may be lowcred to a position closing the front of the scraper bowl for transporting earth in the bowl and a combination ejector and small bowl generally indicated at 19 may be moved forwardly to eject the earth from the bowl when the apron is open. The apron is raised by a cable and lowered by gravity and the combination ejector and bowl 19 is moved forwardly by a cable and returned as by springs which are indicated at 21 and the manner and sequence of these operations will presently be described in detail.

In order to enable complete loading of the main bowl 1%? with the large quantity of earth made possible by its unusual length, the following procedure is followed. First the apron 18 is held in an intermediate position such as that shown in FIG. 1 to receive earth cut by the edge 17 and prevent it from falling forwardly out of the bowl. At the same time, the combination ejector and small bowl 19 is held in a forward position as indicated in broken lines in FIG. 1 and the space between the ejector and apron is filled with earth upon forward movement of the scraper with the cutting edge in the ground. Since the main bowl is in effect small with the ejector in this position, no more than ordinary force is required to fill it with earth. When it is filled, the ejector and bowl 19 is permitted to move rearwardly under the influence of the springs 21 and the force of more earth entering over the cutting edge 17. This rearward movement is facilitated by rollers shown at 23 which engage the bottom 11 of the main bowl.

The small bowl 119 has side walls 24 and a rear portion or ejector plate 25 which is inclined rearwardly from its lower edge 26 so that the capacity of the bowl is relatively great for its overall size. Rearward movement of bowl 119 within the main bowl I'll will effect the movement of a large volume of earth without the usual friction between this volume of earth and the side walls and bottom of the main bowl. The small bowl is also provided with scraping edges such as shown at 27 in FIGS. 1 and 2 inclined toward very close contact with the walls 12 of the main bowl for cleaning the main bowl and assuring ejection of all of the earth when the ejector plate and small bowl is moved forwardly. Just prior to the forward movement for ejecting the earth from the bowl, the apron 18 is raised to its uppermost position to permit free ejection from the forward end of the main bowl.

The cycle of operation just described is not possible with many conventional cable actuated scrapers because of the fact that the ejector of such scrapers cannot be moved to a forward position with the apron in a partially raised or loading position and, therefore, the initial portion of the loading cycle cannot be accomplished. The inability of conventional scrapers to operate in this manner may best be understood from FIG. 3 which discloses the apron and ejector cable system which is well-konwn and previously disclosed in the United States patent to Gustafson, No. 2,573,765.

In FIG. 3, the tubular spreader member 16 and the draft arms 15 are indicated in simple outline. A cable 3%, one end of which is wound upon a winch drum, not shown, on the tractor which pulls the scraper, leads over guide sheaves 31 and 32 into the spreader where it is trained over the sheaves in a movable or sliding block 33 and the sheaves in a stationary block 34. As this cable is taken in by the winch drum, it tends to advance the block 33 toward the block 34 with a mechanical advantage determined by the number of strands disposed between the two blocks. After passing through the sheaves on the blocks 33 and 34-, the cable is carried downwardly through one of the draft arms 15 and passes outwardly through the rear end of the arm over

guide sheaves

35 and 36 thence over a sheave 37. It is then passed through a series of sheaves 38 secured to a rearwardly extending portion of the ejector and a series of sheaves 39 which are secured with relation to the bowl. The end of the cable is made fast as indicated at 40 to an anchor on the bowl. Thus take-in or pulling on the cable 30 is adapted to shorten the distance between the sheaves 38 on the ejector and the sheaves 39 On the bowl so that the ejector will tend to move forwardly in the main bowl. The apron 18 is raised by pulling on a cable 42 also shown in FIG. 1 which is secured to the apron as by an anchor 41. This cable 42 is trained over

guide sheaves

43, 44 and 45 and has its opposite end secured to the sliding block 33 as shown. Because of the connection thus described, any taking up or pulling on the cable 30 tends to shorten the distance between the blocks 33 and 34 and thus through the cable 42 to raise the apron 18. The same pull on the cable 30 tends to shorten the distance between the

sheaves

38 and 39 and to advance the ejector to discharge the contents of the bowl. Raising of the apron is resisted by gravity and forward movement of the ejector is resisted by spring action. Taking into consideration the normal resistance to the operation of the apron and the ejector and also the mechanical advantage that is obtained by the cable 30 passing over the blocks which control the operation of these members, the system is balanced so that the apron will raise more easily or with less force applied to the cable 30 than is required for advancing the ejector. Consequently, when a pull is applied to the cable 30 the block 33 wil be advanced toward the block 34 to raise the apron to its uppermost position before a continued pull on the cable is effective to advance the ejector.

With the foregoing understanding of the manner in which the apron and ejector are actuated by pulling upon a single cable, it becomes apparent that, with this conventional structure, it is impossible to raise the apron to an intermediate or loading position and then to advance the combination ejector and small bowl to the forward position shown in broken lines in FIG. 1 for the pur pose of completely filling the short forward part of the main bowl and thereafter permitting the ejector and small bowl to move rearwardly while filling of the large bowl is completed. To make this operation possible the present invention includes a latch shown at 50 in FIG. 1 which is pivotally supported with respect to the draft assembly of the tractor and adapted to engage any one of a-number of spaced pins 51 supported on the forward part of the apron. This latch is actuated toward a release position by movement of a piston in a slave cylinder 52 which is connected as by a line 53 with a master cylinder 54 disposed within convenient reach of the operators station on the tractor which pulls the scraper, a portion of which is schematically shown at 55. A hand lever 56 controls a conventional piston in the cylinder 54 to transmit pressure of fluid therein to the cylinder 52 for releasing the latch 50.

In operation of the latch mechanism just disclosed, upward movement of the apron through the cable system illustrated in FIG. 3 will be interrupted by engagement oftthe latch with one of the pins 51. The lever 56 may be manipulated to effect engagement with any one of the several pins to regulate the height of the apron depending upon the depth of cut to be made. With the upward motion of the apron thus interrupted, the ejector and small bowl Will be moved forwardly by a continued movement of the cable 30 and the parts are brought into position for the initial portion of the. loading cycle of the main bowl. When the bowl is completely loaded in the manner hereinabove described, release of the latch 50 enables complete raising of the apron and forward movement of the ejector and small bowl to discharge the contents of the main bowl. Thus, a very simple mechanism has been provided for enabling the use of a conventional and very convenient means for actuating an apron and ejector in such a manner that it also actuates a small bowl and ejector within a large scraper bowl and makes possible the proper and emcient loading of the forward por-- tion of the main bowl before the small bowl is retracted. Furthermore, in addition to the reduction of friction effected by the use of the small bowl within the main bowl, the force of the ejector return springs 21 is employed for urging the small bowl rearwardly so that additional power is not required for this purpose.

I claim:

1. In a scraper of the character described which has a main bowl, an apron pivoted with respect to the bowl for swinging movement to and from a position closing the forward end of the bowl, a combined ejector and small bowl closing the rear end of the main bowl and slidable forwardly to eject the contents of the main bowl, and cable controls including a single cable through which pulling said single cable will first raise the apron until it is stopped and then move the ejector and small bowl forwardly, releasable latch means for stopping the apron in a partially raised loading position, said cable being operative to move the ejector and small bowl only after raising of the apron has been stopped by said latch means whereby the ejector and small bowl will move forwardly to reduce the capacity of the main bowl during the initial part of the loading cycle.

2. In a scraper of the character described which has a main bowl, an apron pivoted with respect to the bowl for swinging movement to and from a position closing the forward end of the bowl, a combined ejector and small bowl closing the rear end of the main bowl and slidable forwardly to eject the contents of the main bowl, and cable controls including a single cable through which pulling said single cable will first raise the apron until it is stopped and then move the ejector and small bowl forwardly, releasable latch means for stopping the apron in a partially raised loading position, said cable being operative to move the ejector and small bowl only after raising of the apron has been stopped by said latch means whereby the ejector and small bowl will move forwardly to reduce the capacity of the main bowl during the initial part of the loading cycle, and resilient means for urging the ejector and small bowl rearwardly when tension on said cable is released.

3. In a scraper of the character described which has a main bowl, an apron pivoted with respect to the bowl for swinging movement to and from a position closing the forward end of the bowl, a combined ejector and small bowl closing the rear end of the main bowl and slidable forwardly to eject the contents of the main bowl, and cable controls including a single cable through which pulling said single cable will first raise the apron until it is stopped and then move the ejector and small bowl forwardly, releasable latch means for stopping the apron in a partially raised loading position, said cable being operative to move the ejector and small bowl only after raising of the apron has been stopped by said latch means whereby the ejector and small bowl will move forwardly to reduce the capacity of the main bowl during the initial part of the loading cycle, resilient means for urging the ejector and small bowl rearwardly when tension on said cable is released, and means to engage said latch means for stopping the apron at different positions.

References fitted in the file of this patent UNITED STATES PATENTS 2,112,105 LeTourneau Mar. 22, 1938 2,207,016 Le Bleu ,July 9, 1940 2,251,307 Washbond Aug. 5, 1941 2,305,481 Le Bleu Dec. 15, 1942 2,852,870 Kimsey et al. Sept. 23, 1958 2,984,027 Beck May 16, 1961