US2773320A - Digging and carrying scraper - Google Patents

Description

Dec. 11, 1956 E. R. FRYER ET AL DIGGING AND CARRYING SCRAPER m J R 1 mm B YD m mm H m m m M 8 MM 6 Mm @w 2 5 9 l 1 y a M d e l 1 F Arra/P/vrs D12, 111, 1956 E. R. FRYER ET AL 2,773,320 I: v,

DIGGING AND CARRYING SCRAPER Filed May 14, 1952 6 Sheets-Sheet 2 I VENTOR. fowano FRYER WILLIAM J. ADA/16 Dec. 11, 1956 E. R. FRYER ET AL 2,773,320

DIGGING AND CARRYING SCRAPER Filed May 14, 1952 a 6 Sheets-Sheet 5 INVENTOR. fawn/v0 R. FRYER WILLIAM J: ADAMS A 1- ran -17:

Dec. 11, 1956 E. R. FRYER ETAL 2,7

DIGGING AND CARRYING SCRAPER Filed May 14, 1952 6 Sheets-Sheer. 4

IN VEN TOR. EDWARD R. Fnren Wang! J. Adams AT R EYS 1956 E. R. FR YER ET AL DIGGING AND CARRYING SCRAPER 6 Sheets-Sheet 5 Filed May 14, 1952 IN V EN TOR.

ATTORNEYS Dec. 11, 1956 Filed May 14, 1952 CENTER OF GRAVITY APRON AOAD E. R. FRYER ET AL DIGGING AND CARRYING SCRAPER 6 Sheets-Sheet 6 INVENTOR. FowA RD Fvxsw WILLIAM 11' AOAMS ATTORNEYS United States Patent DIGGING AND CARRYING SCRAPER Edward R. Fryer, Willoughby, Ohio, and William J.

Adams, Santa Cruz, Califi, assignors, by mesne assigneuts, to General Motors Corporation, Detroit, MiClL,

a corporation of Delaware Application May 14, 1952, Serial No. 287,772 7 Claims. (Cl. 37-126) lifting the bowl and actuating the ejector, each being movable independently of the other, wherein each power unit is interchangeable for obtaining economy in manufacture and servicing without sacrificing desirable operational characteristics.

Another object of the present invention is to provide in a digging and carrying scraper of the type described interchangeable power units, as aforesaid, with each exerting approximately the same force but moving the apron, bowl or ejector each at a speed commensurate with its load and over the proper distance for satisfactory performance.

Another object of the present invention is to provide in a digging and carrying scraper of the type described a pull yoke of continuous box beam construction having space for housing means for raising and lowering the bowl and apron while causing minimum interference with the vision of the operator back into the scraper bowl.

Another object of the present invention is to provide in a digging and carrying scraper of the typedescribed a pull yoke having in a housing hydraulic hoists approximately aligned on vertical axes with space between said hoists and having one or more cutouts in the housing permitting sight back into the scraper bowl by the operator.

Another objectof the present invention is to provide in a digging and carrying scraper of the type described a simple, rugged scraper pull yoke eliminating earth spillage, from the heaped scraper load, clogging up around the apronand bowl-raising means while permitting good vision by the operator back into the scraper bowl.

Another object of the present invention is to provide in a digging and carrying scraper of the type described an apron movable with respect to the scraper bowl, power means for raising the apron and novel motion transmitting means between the power means and the apron for causing the apron to move a larger distance than, but in response to, said power means.

Another object of the present invention is to provide in a digging and carrying scraper of the type described a bowl and a bowl raising means including rigid links having means permitting up float of the bowl.

Another object of the present invention is to provide, in a digging and carryingscraper of the type described, a bowl and an ejector for dumping the contents of said bowl wherein said ejector normally accelerates in movin between loading and dumping positions as the load is decreased on the ejector.

Another object of the present invention is to provide in a digging andcarrying scraper of t hejtype described a scraper bowl, an ejector pivoted to the bowl, means for raising the ejector from a loading position to a dump- "ice ing position approximately balanced over its pivot, and resilient means effective only when said ejector is near the dumping position for moving the ejector oil of the approximately balanced position toward said loading position.

Other features of this invention reside in the arrangement and design of the parts for carrying out their appropriate functions.

Other objects and advantages of this invention will be apparent from the accompanying drawings and description and the essential features will be set forth in the appended claims.

In the drawings,

Fig. l is a side elevational View of the lever type digging and carrying scraper in its loading position showing the lines of sight of the driver back toward the scraper bowl during the loading operation;

Fig. 2 is a side elevational view of the digging an carrying scraper of Fig. l in its hauling position showing the lines of sight of the driver back under the scraper bowl so that he can easily check whether or not the bowl i is properly elevated for hauling;

Fig. 3 is a side elevational view of the digging and carrying scraper of Fig. 1 in its dumping or ejecting and spreading position with the lines of sight of the scraper operator shown thereon;

Pig. 4 is a top plan view of the digging and carrying scraper of Fig. l with the lines of sight from the operator back into the bowl shown thereon;

Fig. 5 is a top plan view of a portion of the scraper pull yoke shown in solid lines for clarity and of a portion of the bowl and apron raising mechanism and pressure fluid lines shown in dot-dash lines;

Fig. 6 is a vertical, longitudinal sectional view taken along line 6-6 of Fig. 5;

Fig. 7 is a vertical, sectional view taken along line 7-7 of Fig. 6 through one of the rearwardly extending diverging box beam arms of the pull yoke;

. Fig. 8 is a vertical, sectional view taken along line 8--8 of Fig. 5 through the pentagonal shaped box beam torque tube looking toward one of the pull arms;

Fig. 9 is a sectional View taken along the line 99 of Fig. 6 showing one of the box beam pull arms in cross section and the pressure fluid line therein in dotdash lines;

Fig. 10 is a side elevational view of the ejector and the mechanism associated therewith, wherein the ejector is shown in dilferent operative positions by solid, dotdash, and dot-dot-dash lines; while Fig. 11 is a side elevational view of the digging and carrying scraper with the bowl partially raised toward its fully elevated hauling position and disclosing difierent relative dimensions between the operating scraper parts making possible interchangeability of the hydraulic hoists which operate the. apron, bowl and ejector.

The general construction of the digging and carrying scraper coupled with a pulling tractor is shown in Figs. 1 to 4 inclusive. A tractor 2th of four-wheel type, having two parallel rear drive wheels 21, is of the general type with an engine in the front connected by the usual change speed mechanism and drive mechanism with a rear axle for driving the rear wheels 21. A pull yoke 22 on the digging and carrying scraper is connected to the rear of the tractor by a hitch 23 located between rear wheels 21 and providing pivotal connections therehetween extending along a vertical axis, along a horizontal axis longitudinally with respect to the length of the tractor frame, and along a horizontal axis transverse thereto. This hitch connection may take the form shown in Fig. 3 of the copending U. S. patent application to William J. Adams, entitled Scraper, erial No. 111,496, filed August. 20, 1949 now Patent No. 2,674,815, granted April 13, 1954.

The tractor 26 also carries a source of pressure fluid including a pressure generating device such as a pump and carries control means within reach of the tractor operator connected with conduits leading back to the scraped for operation of the moving parts thereof by fluid pressure.

A scraper bowl 24 is pivotally secured to the rear of the pull yoke 22 and is formed by spaced apart, vertically extending, substantially parallel side walls 24:2, 24a. This scraper bowl has laterally extending box beams 24b, 24c and 24d extending between and welded or otherwise secured to each of the side walls to keep them in the spaced apart relationship. It should be noted that the front or left-hand side of the scraper bowl in Fig. 3 is substantially open between the side walls except for the strengthening of the box beams 2412. Another box beam 242, triangular in cross sectional shape, is located between and welded or otherwise secured to the side walls at the mid-portion of their bottoms. Any type cutting blade may be removably secured to this lastmentioned box beam 24@ for digging the earth or other material during the loading operation shown in Fig. l and for directing it back into the scraper bowl. A specific type of cutting blade especially desirable for this type of digging and carrying scraper is disclosed in a copending U. S. patent application to Edward R. Fryer, entitled Offset Cutting Edge for Scrapers, Serial No. 226,601, filed May 16, 1951.

A rear support for the scraper bowl 24 is provided. Two upper box beams 26, 26, and two lower box beams 27, 27 are each welded or otherwise secured at their left-hand edge in Figs. 4 and 11 to the rear of the bowl and extend rearwardly to meet on the same horizontal line. A push bumper 28 is welded or otherwise secured to the rear of each of the afore-mentioned box beams, and this bumper may be engaged by a pusher tractor or bulldozer with a pushing force when aiding the loading of the scraper or While the scraper is being push loaded. This pusher bumper may make the form disclosed in our copending U. S. patent application Serial No. 283,949, entitled Pusher Bumper, filed April 23, 1952. A rear axle housing 30 is welded or otherwise secured to the box beams and rotatably supports a pair of spaced rear wheels 31, 31.

The open front of the bowl 24 may either be open, as shown in Fig. 3, or be closed by an apron 33, as shown in Fig. 2. The apron has an outwardly convex, smooth outer or front surface extending downwardly and rearwardly and has a pair of spaced side arms 33a, 33a welded or otherwise secured thereto and straddling the spaced bowl side walls 24a, 24:: with the rearward end of each arm pivotally secured to its respective bowl side wall so that the apron 33 may be moved between the closed and open positions shown in Figs. 2 and 3 respectively.

An ejector 34 forms the bottom and rear walls of the scraper bowl and extends between the side walls thereof. It has a bottom wall pivotally connected at its front end by a hinge at 34a to the triangular box beam 242 behind cutting edge 25 and the open front of the bowl. It also has a wall extending upwardly and rearwardly from this bottom wall along a smooth curve to form the rear wall. The ejector 34 can pivot forwardly and upwardly about pivot 34a for dumping the contents of the bowl.

Pull yoke 22 is shown generally in Figs. 1, 2, 3 and 4 and specifically in Figs. 5 to 9 inclusive. The pull yoke may be described broadly as having a pair of arms rearwardly extending from the hitch 23 with the rearward or distal end of each arm being pivotally attached to the outside of the respective bowl side walls 24a, 24a. A space is left between the arms for housing means for raising the scraper bowl 24 and the apron 33. Each arm forms a continuous box beam structure from the hitch to the rearward pivotal connection with its associated bowl side wall to provide a strong, integral structure for lifting and carrying the forward part of the scraper bowl 24 with the load therein, and for withstanding all pulling, pushing and backing loads and other strains which these large scrapers undergo. Also, the pull yoke is so constructed that good visibility is always provided back into and around the scraper bowl at all times since the pull yoke causes a minimum interference with the sight of the tractor driver.

Said broadly defined pair of arms behind said hitch member 23 includes a pair of gooseneck arms 40, 41. These arms diverge in the rearward direction and have a space provided therebetween for housing hydraulic hoists for raising the bowl and apron to be described later in the specification. Each arm is of box beam construction formed by four plates welded together, as shown by plates 46a, 40b, 40c and 40d of arm 40 in Fig. 7 and correspondingly numbered plates for arm 41. Both the innermost vertically extending plates 40b and 41b of arms 40 and 41 and the outermost plates 40a and 41a diverge in the rearward direction. Each arm is in the form of an upwardly arched gooseneck having sufficient arch for clearing the rear wheels 21, 21 of tractor 20 during turning for even a turn. v

It should be apparent that arms 40 and 41 could be replaced by an alternative construction consisting of a single unitary box beam providing some but not all of the advantages of the separate arms 40, 41 since the rearwardly diverging space shown in Fig. 5 between inner plates 40b and 4112 would not exist. This unitary box beam would have outermost plates 40a and 41!; rearwardly diverging but upper plates 40c and 410 and lower plates 40b and 41b would be replaced by a single solid upper plate and a single solid lower plate with each welded to both outer plates 40a, 41a and bridging the span therebetween to hold the spaced outer plates together. This box beam would have the same rearwardly diverging plates 40a and 410 as arms 40 and 41 and would be designed with a cutout to provide a space therebetween for the hydraulic hoists for raising the bowl and apron, presently to be described.

To the rear of this diverging portion of the yoke is secured a torque tube welded to the rear of each rearwardly extending plate in the diverging portion and forming arms extending laterally on each side thereof. In the drawings, the torque tube as shown at 43 is formed from plates welded together .and forming a pentagonal or five-sided box beam. The construction of the torque tube 43 is best understood by considering it as a onepiece tube extending between pull arms 44, 44 so that it not only extends laterally on each side of the diverging gooseneck arms 40, 41 but also bridges the space between them.

A cutout is formed in the torque tube between the diverging arms 40, 41 to provide a hoist housing for mounting the hydraulic hoists for raising the apron 33 and the bowl 24. This cutout is formed by cutting away portions at least in the top and bottom walls of the torque tube 43 between the diverging arms. However, this cutout is spaced forwardly from rear wall 43a of the torque tube in Fig. 6 with the hoist housing having a plate 46 extending generally in the same direction as torque tube rear wall 43a and welded or otherwise secured to the top and bottom torque tube walls at the rear of the cutout for forming a rectangular box beam structure behind the cutout. Hence, the torque tube 43 is a continuous box beam structure consisting of two box beams, each pentagonal in shape, joined by a box beam rectangular in cross section. The hoist housing also includes side walls 47, 4'7 and a front wall 45 welded to each other, to the arms 40 and 41 and to the torque tube 43 wherever they meet to provide a strong structure. A sight opening 45a is provided in the upper, central portion of the front hoist housing plate 45 between the arms 40 and 41 and has a heavy, round, band rim-weld around it to reinforce the opening. The purpose of the opening and the rim-weld will be set forth more detail later in the specification.

g This torque tube 43 is located behind the rear wheels 21, 21 of the tractor so as to be closer to the ground for several reasons. The low torque tube has a low center of gravity so that the scraper has maximum stability when either empty or loaded. Also, as will be shown later in the specification, the tractor driver can more readily see back into and around the bowl in all operating positions.

The pull arms 44, 44 are shown in Fig. 4 as being welded or otherwise secured to the outer ends of the torque tube 43 and extending rearwardly to piyotalconnections at 44;, 44 with the bowl side ,walls. Fig. 9 shows one of the pull arms in section with anouter plate 44a, inner plate 44b, bottom plate 44d, intermediate wall 44c and downwardly inclined top plate 448 all welded or otherwise secured together to provide a continuous box beam structure throughoutthe length of each pull arm. In Fig. 8, either one or both plates 44c and 44d are extended forwardly from the main part of the pull arm, wrapped around the torque tube 43 at its outer end, and welded thereto to form a strong structure. The rearward end of each pull arm 44 is pivotally attached at 44 to its respective bowl side wall 24a intermediate the ends of the bowl, about midway between the front and rear thereof.

This pivotal mounting has two advantages; First, it concentrates all the rear weight of the pull yoke and of the hydraulic cylinders (for raising the bowl and apron) onto the cutting blade 25 so that the scraper bowlwill readily dig even the most difficultto-cut soils. Second, this construction enables a hydraulic hoist with a relatively short stroke to lift the scraper bowl 24 a large distance.

The pull yoke 22 forms a continuous box beam structure from the hitch 23 to the pivots 44f, 44f since the diverging arms 4t and 41, the torque tube 43 with the hoist housing plates thereon, and the pull arms 44, 44 each have a torsional resisting box beam structure and the component plates are securely welded together. The housing for the hoists used in raising the apron 33 and the bowl 24 do not interrupt the continuity of the continuous box beam structuresince it is located between the diverging arms 40 and 41 within a cutout in torque tube 43, and the torque tube 43 is a continuous box beam between the pull arms .44, 44 including a rectangular box beam structure behind the cutout bounded at the front and rear respectively by plate 46 and wall 43a inFig. 6 for keeping the arms 4% and 41 spaced apart and for strengthening the structure. This continuous box beam structure eliminates twisting and weaving betweenthe scraper assemblies and holds both ends of the cutting blade 25 solidly during either the digging operation as in Fig. l, or the spreading and ejecting operation, as in Fig. 3.

The means for raising the bowl and the means for raising the apron have many parts in common and are clearly shown in Figs. 1 to 6 inclusive. Each has a power means or power unit including one or more hydraulic hoists d, 51 and 52 with said hoists being located between the diverging arms 40 and 41 and being approximately laterally aligned on vertical axes on the pull yoke 22. The two outer hoists 5d and 52 are operatively connected to the bowl 24 for raising it. The center hoist 51 is operatively connected to the apron for moving it between its lowered or closed position in Fig. 2 and its elevated or open position in Fig. 3.

At the lower end of the hoist housing, each hoist has a pair of support bars 53 and 54 welded at opposite ends to the front and rearplates 45 and 46 respectively of the hoist housing for tying the bottom of these plates together and strengthening the pull yoke. The three pairs of crossbars, 53 and 54 (six crossbars in total), are mounted in the hoist housing in horizontal alignment and each pair of bars ha's aligned holes therein formounting a pivot pin 55 therethrough. Three hoists require three pins 55, all shown as beiugcoaxially' a'ligued. The lower end of each hoist pivotally "securedon its pin 55 so that each hoist can pivot between the plates 45and 46 of the hoist housing in Fig. .6 asit raises Ior lowers the bowl or apron.

At the upper end of the hoist housing, a bridge truss 59 is welded to the top of each of the arms and .41 and spans the distance therebetween. The lower surface of this truss 59 is also welded to the upper edge of the front plate of the hoist housing for making the pull yoke 22 a still more rigid structure. A plurality of lugs 59:} are welded to extend upwardly from the bridge truss 59 and have aligned bearing holes therethrough for rotatably supporting a one-piece pivot pin 60. A plurality of levers 56, 57 and 58, one for each of the three hydraulic hoists, are pivotally connected at their forward ends along a common axistosaid pin 60 and extend rearwardly toward the scraper bowl24. Each lever consists of a pair of identically shaped, laterally spaced side members, as shown in Fig. 4.

Each of the three hoists consists of a cylinder member and a piston member, see Fig. 6, wherein the cylinder member of hoist 52 is designated as 52a and the piston member as 52b. In the present disclosure the cylinder member 52a is pivotally mounted at its lower end on one of the three coaxiall-y aligned pins on the pull yoke while the piston member 52b is pivotally mounted at its upper end to the lever 58 between the lever side members and intermediate the ends of the lever. However, it should be apparent that the same lifting action on lever 58 would result if members 52a and 52b were interchanged so that the pivotal mounting on the upper end of piston member 52!) was on pin 55 at the lowest position of the hoist. The lower pivotal mountings of the hoists 5t), 51 and 52 are coaxial on the three pins 55.

The front and rear hoist housing plates 45 and 46 respectively have definite purposes in the structure. The front plate 45 ties together the inner surfaces of the two arms 40 and 4d, the front end of the two pentagonal torque tube shapes of torque tube 43 straddling the hoist housing, and the truss 59 by being secured to each by welding. It should be noted that the front wall 43b of the torque tube 43 may either be cut out between the side plates 47, 47 of the hoist housing, as illustrated, or be acontinuous plate between pull arms 44, 44 with the front hoist housing plate 45 welded thereoveri The rear hoist housing plate 46 separates the three hydraulic hoists from the bowl 24 to prevent the heaped load in the bowl from falling forwardly onto the hydraulic hoists, not only when the scraper is being loaded in the conventional manner in .Fig. l, but also during top loading when a shovel means is dropping aload of .dirt into the bowl 24. The rear plate 46 prevents dirt spillage from the heaped scraper bowl load over the top ofthe apron 33 into the'hoist housing. Lumps .of dirt in the hoist housingwould tend to jam the pivotal. movement of the hoists about the pins 55. However, if any does accidentally enter the hoist housing, it .can easily drop through the bottom opening between the side plates of the hoist housing and the various support bars 53 and.54.

Each of the hoists 50, 5d, and 52 is single acting and the hydraulic pressure fluid therein moves the piston memberl-out of the cylinder member and raises either the bowl or-the apron. The bowl .or apron is lowered when no more pressure fluid is supplied to the hoist and the hydraulic fluid therein ispermitted to drain back throughthe original supply conduit. Thevertical alignment of the hoists adds the .weight of the piston member and lever to the. weight of either the apron or the bowl to force the pressure fluid from the hoist so that the apron or bowl will drop rapidly after the supply conduit begins to serve as a discharge conduit. l

The vertical alignment of the hoists has other advantages. The piston member and cylindermem ber are held 7 in alignment so that the amount of friction and wear therebetween is reduced and less leakage occurs. However, when leakage occurs, it is confined to a small area and the leaking fluid will run down the hoist and out the open bottom of the hoist housing to the ground since the hoists are located ahead of the scraper bowl 24. The pressure fluid cannot leak down onto the inner surface of the apron 33 to cause a dirt build-up thereon.

It should be noted that the bottom of the hoist housing is open not only to permit any dirt in the hoist housing or leaking pressure fluid from the hoists to fall through to the ground but also to permit easy servicing of the pivotal connections between the hoist and the pull yoke at pivot pins 55.

Means are provided for raising the bowl between a lowered deep-digging position, in Fig. l, and an elevated high-carry position, in Fig. 2. This means includes the power unit comprising hoists 0 and 52 and includes a motion transmitting means operatively connected to the hoists and the bowl 24 and movable in response to the hoists for raising the bowl a short distance with great force. The levers 56 and 58 of this motion transmitting mean have already been discussed, and since each lever has on its rearward distal end the same type of connection with the bowl, only the connection on lever 56 in Fig. 2 will be described. A connecting link 62 is provided with its lower end pivotally secured to the box beam 24b of the scraper bowl at 62a. The upper end of the link 62, located between the side members of lever 56, has an elongated slot 62b slidable on a pin on the lever 56 bridging the gap between said side members.

A flexible cable is generally used instead of thi connecting link 62 to raise and lower the scraper bowl, but as the bowl lopes or bounces as it is being carried forwardly at a rapid rate in the Fig. 2 hauling position, the cable of the prior art tends to "stretch and this in turn not only multiplies the bounce but shortens the cable life. Our novel connecting link 62 eliminates the troublesome, costly disadvantages of a cable but preserves all the advantages thereof. The bowl can up float when the cutter 25 is digging and scooping up rocky and stony earth soils so that the cutting edge can feel its way during the digging operation. The connecting link 62 is a solid but slotted lift rod for controlling the bowl and cutting edge while permitting the desirable up float and eliminating the disadvantages of a cable.

The particular pivotal relationship between the parts provides the present scraper with many advantages. The pivots under discussion are located at the opposite ends of each lift hoist 50 or 52, at opposite ends of the lift levers 56 and 58, at opposite ends of each connecting link 62, at 44f between the rearward end of each pull arm 44 and its respective bowl side wall 24a, at the rear wheels 31, 31, and at the horizontal transverse axis pivotal connection of the hitch 23. First, approximately the same mechanical advantage exists throughout the whole lift range \between the lifiting force exerted by the hoist and the downward force exerted on the links 62 by the bowl 2-4 and the load. Each link 62 remains at all times approximately parallel with its associated lift hoist, and the hoist and the link 62 form the same angle at any one position with their associated lever. Hence, the lever 'arm from the pivot pin 60 extending perpendicular to the line of force application by the hoist and the lever arm from the pivot pin 60 extending perpendicular to the line of force application of link 62 always bear the same pro portional relationship to each other. Therefore, an approximately constant fiuid pressure will lift the bowl throughout its entire lift range since the pivotal connect-ions are so designed that lifting the bowl puts a uni form load on the hoists 50 and 52. Second, the scraper has a lower overall height and better stability ince the scraper lifts itself by its own bootstraps. When the cutting edge 25 is lifted, the pull yoke 22 and the hydraulic hoists thereon are also lifted but to a lesser degree 8 to obtain greater movement at the cutting edge 25 relative to the ground than the movement by the hoists would indicate. The torque tube 43 can be mounted in a low position so as to cause only a minimum interference with the vision of the tractor operator back into the scraper bowl 24.

Means is provided for raisingapron 33 between positions closing (-Fig. 11) and opening (Fig. 3) the open front of the" scraper bowl 2-4. This means includes the power unit or lift hoist 51 between and in line with the bowl lift hoists 50 and 52. It also includes a motion transmitting means connecting said hoist S1 to the apron 33 and movable in response to said hoist for raising said apron a greater distance per unit movement of the hoist than the bowl is raised per unit movement of its hoist. This motion transmitting means includes not only the lever 57 pivoted at its forward end on pivot pin 60 and pivotally mounted intermediate its ends to the hoist 51 but also a movement multiplying means between the lever 57 and the apron 33. This means operatively connects the distal end of the lever 57 and the apron 33 for causing the apron to move at a more rapid rate than the distal end of the lever but in response to the movement of the lever. it includes in Fig. 3 a pulley 64 rotatably mounted on the distal end of the lever between the lever side members and a flexible cable 65 operatively connected at one end to the lower front edge of the apron at 66, operatively connected at the other end to the pull yoke at 67 and forming a bight over the pulley or sheave 64. The cable end connections 66 and 67 each consist of a quick knockout type cable wedge and ocket for securing the ends of the cable respectively to the apron lift and to the back plate 46 of the hydraulic hoist housing. The connection 66 also includes a pivot between the socket and the apron lift so that the cable 65 can freely assume either the position in Fig. 3 or the position in Fig. 2. Note that the flexible cable 65 engages under the downwardly and rearwardly extending outwardly convex surface of apron 33 so that cable 65 is always kept in about the same position in front of the bowl during raising of the apron.

It should now be apparent that the apron is raised a much larger distance than the bowl when the hydraulic hoists moving each member are raised a uniform distance. Other types of movement multiplying means may also be used, if desired. For example, a different type of pulley and cable arrangement or other type of mechanism might give the desired mechanical advantage. The pulley 64 could even be connected to the hydraulic hoist 51 in a different manner to provide the desired motion transmitting mechanism between the hydraulic hoist and the apron.

The flexible cable 65 and the single acting hoist 51 eoact together to permit the apron lip to float down onto the stream of incoming earth in Fig. l as the loading operation is finishing. Hence, the apron lip can feel its way through the stream of earth so as to gently cut oif the flow of earth, while the scraper bowl is being lifted to the carry position in Pig. 2, to prevent the earth from sliding out of the scraper bowl 24 between the scraper lip and the cutting edge 25.

Means is provided for moving the ejector 3'4 between its lowered, retracted loading position in Figs. 1 and 2 and its elevated dumping position in Fig. 3. This path of movement is clearly shown in Fig. 10. This means includes a power unit or hydraulic hoist '70, similar in structure to hoist 50, 51 and 52 previously described, having a cylinder member 7% and a piston member 76!). The rear end of the hydraulic hoist 70 is pivotally connected on a diagonal brace 71 welded at its opposite ends respectively to therear axle housing 30 and to the scraper bowl 24 at the laterally extending rear box beam 240.

Motion transmitting means is provided for accelerating the movement of the ejector over approximately the entire distance from the lowered or retracted position to the dumping position when the movement caused by its hydraulic hoist is at a constant rate. This means includes a lever 72 pivotally mounted at its upper end at 72a under the laterally extending box beam 24c. The opposite or lower end of the lever is adapted to make a relatively moving contact with the outside surface of the ejector by a means shown specifically in this disclosure as a roller 73 rotatably mounted onits movable lower distal ends.

Since this lever 72 and pivot 72a are located under the box beam 24c and behind the ejector 34 which contacts the box beam 24c at its upper edge in the loading position in Fig. l, and in the carrying position in Fig. 2, the lever 72 and the pivot 72a are protected. They are only exposed during the ejection operation as inFig. 3, when protection is not especially necessary. When the parts assume the position in either Figs. 1 and 2 and the bowl 24 is being loaded from 'the top by a power shovel, a lump of dirt accidentally falling behind the ejector 34 will be deflected by the box beam 240 so as not to harm either the lever 72 or the pivot 72a.

It should be noted that the lever 72 extends downwardly from the pivotal mounting 72a and conforms in shape to the outside surface of the ejector. A hardened travel Wear plate '74 is welded to the bowl and has an outside surface conforming in shape to the outside surface of the ejector. During the ejection operation, the natural outer curvature of the ejector and the hardened wear plate 74 coacting with the roller73 on the lever 72 play an important part in getting a desirable ejection action.

The front end of the hoist 70, at the left in Fig. 10, is pivotally mounted on the lever '72 intermediate its ends between pivot 72a and roller 73. In the present disclosure, the hydraulic hoist cylinder member 76a is pivotally mounted to the brace 71 while the hydraulic hoist piston member 7% is pivotally mounted to the lever 72. However, it should be apparent that the same ejection action would be obtained if these hydraulic hoist members were interchanged in their pivotal mountings. Both the pivotal mounting between brace 71 and the hydraulic hoist '70 and the pivotal mounting 72a are fixed with respect to the scraper bowl 24.

The ejection action should now be quite clear. As pressure fluid is admitted into "the hoist '70 from the pressure source and control means on the tractor 29 by way oi the conduit 700 in Figs. 2, 5 and 9, the cylinder member 7% and the piston member 7% are forced apart to cause a relative separation between the pivotal connections on the opposite ends of the-hoist 7%. This action causes the roller 73 on lever 72 toroll along the wear plate 74 to pivot ejector 34 upwardly around its pivotal connection 34a on the bowl 24 from the retracted position in Fig. 2to the dumping position in Fig. 3.

in Fig. 10, the mechanism is shown in several intermediate positions. Along are A, having its center at pivot point 72a, a series of dots have been placed, one dot designating the position of lever 72 for each unit distance increase in separation between the pivotal end connec tions on the hydraulic hoist 70. Corresponding positions of ejector '34 are shown by dots on arc B, having its center at pivot point 3461. Since the distance in the counterclockwise direction between the first five dots on are B increases as ejector 34 moves toward the dumping position, the ejector 34 must accelerate over this arcuate distance when there is a uniform rate of extension of hydraulic hoist 79.

The distance between the fifth and sixth dot on arc B, measuring in the same counterclockwise direction, however is not as large as the distance between the fourth and fifth dot so a slight deceleration takes place. Howover, most of the material is off of the ejector 34 by the time the ejector reaches the fifth dot position on are B in its maximum acceleration. However, the forward momentum of any material still remaining'on the ejector 34 will earryit forwardly and off of 'the 'ejeotor as the ejector deeelerat'es between the fifth and sixth "dot posttions. .Also, ejector -34 engages stops on the bowl 24 in the sixth dot position to prevent further forward travel. The deceleration period reduces the wear on these stops by reducing the forward rate of movement of ejector 34, but still when the ejector 34 engages the stops, this action still gives a good bump" against the stops for cleandumping sticky earth from the inner surface of the ejector 34.

It should be noted that the length of the lever 72 be tween the pivotal connection 72a and the roller 73 is greater than one-half the distance between the pivotal mounting of the ejector lever at 72a and the pivotal mounting of the ejector 34 to the scraper bowl 24 at 34a. It should also be noted that the relatively moving contact between the roller 73 and the plate 74 is on opposite sides of the line connecting the pivotal mountings 34a and 72a when the ejector 34* is in the retracted or full line position in Fig. 10 as compared with the dumping or dot-dot-dash line position. This relationship keeps the contact surface between the roller 73 and the plate 74 down to a minimum so that the length of plate 74 need not be too long. In Fig. 10, the roller 73 moves forwardly toward the ejector pivot 34a between the solid line and the dot-dash line position and then backs up along the plate '74 between the dot-dash and the dot-dotdash line positions.

The lever 72 and the connections thereto give a combined wedge and roller leverage lift action to the ejector 34. At the start of the dumping action when ejector 34 is in the solid line position in Fig. 10 and full load is on the ejector, a uniform rate of extension between the opposite pivotal connections on the hydraulic hoist 70 will move the ejector 34 slowly and with a maximum lifting force. As the load on the ejector 34 decreases, it will move at a faster rate. Hence, the speed of movement of ejector .34 varies approximately inversely with the load, and the force exerted by the hydraulic hoist on the ejector varies approximately directly with the load being moved during the ejection stroke.

When t-heejector 34 is in the dot-dot-dash line dumping position in Fig. 10, it is approximately or nearly balanced over the pivotal connections 34a. Since the hydraulic hoist 70 is a single acting hoist, a spring return means must be provided for pulling back the ejector from the dot-dot-dash line position to where the Weight of the ejector becomes fully effective to drop it to the retracted or solid line position in Fig. 10. This spring return means is specifically shown in the present disclosure as including a spring 76 connected at one end to the bowl 24 in the zone of the lever pivot 72a and a-t't-he other end to an apertured lug 77 "welded to the outer surface of "the ejector. The word zone is intended to mean any point in the immediate neighborhood of the pivot 72a providing the desirable functions attributed to this spring.

It should be noted that the spring 76 does not greatly stretch in length in view of the long travel or" the ejector 34. Since the distancebetween the end connections of spring 76 is approximately the same as or less than the distance between the lever pivot point 720 and its re1atively moving contact With the ejector by roller 73, when the ejector is in its solid line retracted position, the spring 76 does not materially increase in length, to store force for returning the ejector34 to the retracted position, until the ejector approaches its dumping position wherein it is approximately balanced over the pivotal mounting, as shown in the dot-dotdash position in Fig. 10 The spring 76 is normally relaxed and does not increase in length in direct proportion with the movement of the ejector 34 to create aforce opposing the power stroke of the hydraulic hoist 7%. For example, when the ejector is in thedot-dash position the spring would be stretched less than when theejeotoris in the solid line position. However, thespring' 76 gives a strong pull when the ejector-34 is in the :dot-dot-dash line position toUmove it clockwise from its approximately or nearly balanced position over the pivot 34a. It should be noted that the laterally extending box beam 240 in Fig. 10 and the ejector 34 in the solid line position protect not only lever 72 but also spring '76 during loading (Fig. 1) and carrying (Fig. 2). This is especially desirable when the scraper bowl 24 is being top-loaded by a power shovel.

Figs. 1 to 4 inclusive disclose that the parts of this scraper are arranged for maximum vision by the tractor operator back into and around scraper bowl 24. This increased visibility with minimum sight interference is possible only because of the novel design of the pull yoke 22 and of the means for raising the scraper bowl 24 and the apron 33.

The tractor operator has a clear line of sight under the torque tube 43 between the rear tractor wheels 21, 21 and between the rearwardly diverging gooseneck arm 45 and 41 whenever necessary. During loading in Fig. 1, he has a clear line of sight in the zone between lines C and D over the rear of the tractor frame and under the torque tube 43. The cutting action at the cutting blade 25 and the flow of soil into the scraper bowl 24 can be easily observed. During hauling in Fig. 2 after the scraper bowl '24 has been raised, the tractor operator can readily see in the zone between the sight lines E and F to be sure that there is sufficient clearance under the scraper bowl at all times. During dumping in Fig. 3, the tractor operator can readily see in the zone between the lines G and H to control the dumping and spreading operation as the dirt emerges from the scraper bowl 24.

During the loading operation in Fig. 1 when the load of earth is building up within the scraper bowl 24, the tractor operator can readily see over and between the lift levers 56, 57 and 58 in the zone bounded by lines I and J in Fig. 1 over the front hoist housing plate 45 back into the upper part of the scraper bowl 24. The hydraulic hoists 50, 51 and 52 are collapsed and out of sight during the digging or loading operation in Fig. 1 when unrestricted rear vision is most needed. The leverage is such that the hydraulic hoists are still within the height of the gooseneck arch of the pull yoke. The levers 56, 57 and 58 extend rearwardly from their pivotal connection 6i) in the direction of the line of sight of the tractor operator looking toward the scraper bowl so as to cause a minimum interference with his line of sight. The levers are in their lowest position, being inclined below the horizontal, during loading in Fig. 1 so that they do not interfere with the rear view of the operator above the pull yoke. The hydraulic hoist 50, 51 and 52 are extended only in the hauling position in Fig. 2 and the dumping position in Fig. 3 when unrestricted rear vision into the upper portion of the scraper bowl 24 is not needed.

The tractor operator can see between the diverging arms 40 and 41 in Figs. 1, 3 and 4 back into the scraper bowl 24. He can see through the sight opening 45a in Fig. 6 between the hydraulic hoists 50, 51 and 52 in Figs. 4 and 5 back into the scraper bowl 24 while loading (Fig. 'l) and dumping (Fig. 3). His line of vision is within the zones bounded by lines KL and lines MN in Fig. 4. The cutout in the torque tube 43 for the hoist housing has been especially made so that the hydraulic cylinders 50, 51 and 52 are located at their rearmost position for the widest transverse in-line spacing to provide maximum sight spacing between each hoist. Typical lines of vision back into the scraper bowl and through the sight opening 45a are shown at O and P in Figs. 1 and 3. While the operator is looking back through the sight opening 45a into the scraper bowl, he can also watch the action of the hoists 50, 51 and 52 to be sure that they are operating correctly.

The sight opening 45a in Fig. 6 has still another purpose. The pressure fluid conduits from the pressure source and the control means on the tractor lead back along the inner side of one of the gooseneck arms 40 or 41 through this opening 45a to the hydraulic hoists 50, 51, 52 and the ejector hoist 70. The conduits to hoists 50, 5'1 and 52 are connected to the front sides thereof in Figs. 5 and 6 as the level of the opening 45a for quick and easy access for detaching or attaching the conduit to each hydraulic hoist. The round, band rim-weld around the edge of opening 45a provides a round guide surface for the conduits for preventing damage to them.

If the diverging gooseneck arms 40 and 41 were replaced by a unitary box beam, as mentioned earlier in the specification, it would be impossible 'for the tractor operator to see through the box beam in the same manner that he could see between the diverging arms 40 and 41 back through the sight opening 45a and between levers 56, 57 and 58 into the scraper bowl 24.

The tractor operator can also see back into the scraper bowl 24 by looking outside of the rearwardly diverging gooseneck arms 40 and 41 above the line Q in Fig. 4 and below the line R. This is shown in Fig. 3 as line S to the outside of arm 41 and over torque tube 43 back into the scraper bowl 24 when the scraper is dumping the load because of the low position of the torque tube 43. The arms 40 and 41 diverge in the direction of sight of the tractor operator back into the scraper bowl to form a minimum area of sight interference for He has clear vision on each side of the gooseneck arms since the hydraulic hoists 50, 51 and 52 are between the arms 40 and 41 and behind the gooseneck arch.

Windows 33b, 33b are provided in the apron 33 spaced outwardly from each diverging arm 40 or 41. The tractor operator can readily see through the windows 33b, 33!) back into the scraper bowl during the loading operation in Fig. 1 to see when a full load has been scooped up. Each window has a screen mesh thereover to prevent the scraper load from dropping out of the bowl. Each window is elongated vertically or in the direction of apron opening movement so that the tractor operator can readily see through it for different apron openings. Soft materials, such as coal, sand, etc, require that the apron be raised higher than for some other materials. A high apron position with a large digging throat permits a deep cut to be taken and a large volume of material to enter the scraper bowl 24.

Increased visibility is created by several factors in the design, among them being the low position of torque tube 43, the novel motion transmitting means connecting the hydraulic hoists to the apron and bowl, and the location of the hydraulic hoists in a cutout in the torque tube 43 between the rearwardly diverging gooseneck arms 40 and 41.

The low position of the torque tube 43 behind the tractor drive tires 21, 21 permits the tractor operator to see into the scraper bowl 24 and to see the pusher tractor back at the pusher bumper 28, if necessary. He can see not only through the sight opening 45a in the hoist housing but also over the low torque tube 43 outside of the rearwardly diverging arms 40 and 41. It also gives the scraper good stability whether empty or loaded. Of course, the low position of the torque tube 43 requires a gooseneck arch in the rearwardly diverging arms 44) and 41 to clear the rear wheels 21, 21 during turning.

The low placement of the torque tube 43 is made possible by other features of the design. First, the pivotal relationship between the scraper parts including the pivots located at the opposite ends of each lift hoist, 50 or 52; at opposite ends of the lift levers 56 and 58; at opposite ends of each connecting link 62; at pivot 44 between the rearward end of each pull arm 44 and its respective bowl side wall 241;; at the rear wheel 31, 31; and at the horizontal transverse axis pivotal connection of the hitch 23. The scraper has a lower overall height and better stability since the scraper lifts itself by its own bootstraps. When the cutting edge 25 is lifted, the pull yoke and the hydraulic hoist thereon are 13 also lifted but to a lesser degree to obtain greater movement at the cutting edge relative to the ground than the movement by the hoists per se would indicate. The low torque tube 43, possible with thisdesign, causes minimum interference with the vision of the tractor operator back into the scraper bowl.

Second, the mechanical advantage of the motion transmitting means with their placement between each hydraulic hoist and associated bowl or apron makes possible a low torque tube. The hydraulic hoists G, 51 and 52 with the motion transmitting means secured to each must exert "a maximum lifting force on the bowl and apron for easy and fast operation. The hoists, lift levers 56, 57 and 58, the pivot pins thereon, and the pulley 64 must be grouped together into a compact unit to create minimum interference with the sight of the operator back into the scraper bowl but still all parts must be readily accessible for disassembly andrepair. Since the hoists are mounted between the rearwardly diverging arms 40 and 41, they must be located in a cutout in the torquetube'so as to be positioned as far to the rear as possible so that the tractor operator can sight through the opening 45a in the hoist housing 'and between the hoists back int'o'ihe'scraperbowl 24.

The three means for raising the bowl, apron and ejector each include identical hydraulic hoists 50, 51, 52 and 7t) and include motion transmitting means between said hoists and the apron, bowl or ejector.

Each hoist is identical in construction and interchangeable with each of the other hoists. Each hyd'raulic hoist is single acting and has a single pressure fluid conduit connected with the pressure source and the control means operable by the tractor operator. "lhepre'ssure 'fluid lifts the bowl, apron or ejector while the weight of each assembly causes it to lower as the pressure is decreased in its conduit and the pressure fluid is permitted to escape from the hydraulic hoist backto a main reservoir. Each hydraulic hoist has the same length working stroke andbore size and has a cylinder member and a piston member with each member havused to advantage in the present digging and carrying scraper is completely disclosed in the copending U. S. patent application entitled Hydraulic Hoist Construction, to Raymond Armington and Harold C. Schindler, Serial No. 71,056, filed January 15, 1949, now abandoned, and vin the copending continuation-id part application thereof, Serial'No. 277,176, now Patent No. 2,692,584, granted October :26, 1954. The operations of raising and lowering of the scraper bowl 24, ofmoving the apron 33, and of moving the ejector 34 are. performed independently of each other. Each is operable independently so the apron or bowl or ejector may be moved without moving the other two mentioned movable scraper parts. Three pressure conduit line controls are provided on the tractor for manipulation by the tractor operator, one controlling the apron liftthydraulic-hoist 51, one controlling the bowl lift hydraulic hoists 50 and 52, and the other controlling the ejector lift hydraulic hoist '70.

The motion transmitting means between each hoist and its associated ,part for the bowl, apron and ejector even have features in common. Each includes a lever pivotally mounted at one endto one of the large scraper parts, either the pull yoke 22 or the bowl structure,

pivotally mounted intermediate its ends to its associated sure can be used even though the load, distance of movement, and desirable rate of movement differs for the bowl, apron and ejector. Since the hydraulic pressure for each hydraulic hoist is substantially the same under full load conditions, the force exerted by the hoists to raise, at full load, either said apron or ejector or bowl divided by the mechanical advantage of the associated motion transmitting means for each hydraulic hoist bears a relationship of approximately 1:1:2 respectively for the raising means of the apron, ejector and bowl. In other words, this ratio corresponds to the number of hoists used-one for the apron, one for the ejector and two for the bowl-since the working pressure at full load in each hoist is the same.

Although approximately identical operating pressures and identical hydraulic hoists are used, the force, length of movement and desirable speed of movement of the bowl, apron and ejector vary. Hydraulic hoists 5i) and 52 for raising the scraper bowl 24 must raise the bowl a short distance with great force since they must raise not only the heavy bowl but the full load therein. The load on the scraper bowl hoists is substantially the same throughout the range of'their movements and the lever arms 56 and 58 havebeen designed so that each forms the same angle with its connecting link 62 as it forms with its associated hoist at the same time. Although these angles change as the bowl is raised, approximately the same proportion always exists between the length of the lever arm extending perpendicular from the hydraulic hoist to the pivot 60 and the length of the lever arm ex tending perpendicular from the link 62 so that uniform hydraulic pressure in the lift hoists causes a uniform lifting force to be applied to the scraper bowl.

In contrast, the apron 33 must move a greater distance per unit movement of its hydraulic hoist 51 than the bowl per unit movement of its hydraulic hoists. The hydraulic hoist 51, having the same length of stroke as hydraulic hoists 50 and 52, not only must be able to raise the apron the same height as the bowl lift hoists lift the bowl to keep the same relative position therebetween but also must be able to lift the apron from its closed or full load position in Fig. 11 to its elevated and open position in Fig. 3. It must be able to raise the apron at full load for desirable scraper operation about twice the distance at about twice the speed of said bowl raising movement. Hence,the apron 33 requires only about one-quarter of the lifting force required by the scraper bowl 24.

The desirable movement of the ejector 34 is entirely different. In contrast with the uniform load on bowl hoists, the load on the ejector 34 decreases as it is moved from the solid line position to the dot-dot-dash line position in Fig. 10 as the material slides: cit of the inner surface of the ejector. To cut dumping time, accelerating movement of the ejector as it moves forwardly is desirable. As fully disclosed previously in the specification, the ejector 84 accelerates over approximately the entire distance from the full load soiid line retracted position to the dot-dot-dash line dumping position when the hydraulic hoist expands at a constant rate. There is a slow movement with maximum force at the start of the dumping action at full load. The speed of movement increases as theload on the ejector becomes lighter so that the speed varies approximately inversely with the load on the ejector and the hydraulic hoist 7i) exerts through lever 72 a force on ejector 34 varying approximately directly with the load on the ejector being moved.

The advantages in using interchangeable hydraulic hoists while maintaining the most desirable operating action of the scraper bowl 24, the apron 33 and the ejector 34 are many. Interchangeable hydraulic hoists lower manufacturing costs since the manufacturer can machine standard parts in larger lot sizes, carry a smaller inventoryiof finishedpar'ts and raw materials, and assemble the hoists in less time since labor saving devices can be justified in view of the larger production reducing amortization costs per piece on such devices. The scraper has a lower upkeep cost since the manufacturer, distributor and user can carry a smaller inventory of hydraulic hoists and component parts while always being sure that they will have the needed part at the right time when a breakdown occurs. Only a single conduit connects each hoist with the control means on the tractor since each hoist is single acting and not double acting.

Fig. 11 shows the present lever type digging and carrying scraper with approximate working dimensions set forth thereon so that we may consider the approximate hydraulic operating pressures and range of movement of each part based on reasonable estimates of the loads generally encountered.

The force involved in the bowl lift can easily be calculated. The cutting edge 25 has about a 46" vertical movement, including a 14" dig below ground and a 32" lift above ground. The lift beam (front of bowl) travels I/ 46= 56 travel The ball joint 44 travels The pull yoke travels X46"=36 travel with respect to the ground from hitch 23 to ground at dimensions from the hitch 23 to the lift link 62. The lift or connecting link 62 travels 56"24"=32 travel with respect to the pull yoke 22.

The load on the end of the lift lever is 155 20,000# (load On hitch 23) 64 (ball joint 44 f to link 62) X2 (levers) on each lift link 62 and on each lift lever 56 and 58.

The approximate full load on the apron lift lever 57 can be easily caclulated. Assuming a 12,000# load at the center of gravity of the apron, then the cable load is The pulley 64- on the end of the lift lever 57 doubles the travel of cable 65 and also doubles the load on the pulley or distal end of the lever 57 and this load is 2 8,000#=16,000# load 12,000# =8,000# load 2+24 (yoke travel with ground) 115 or approximated in another manner as being equal to the relative travel between the front portion of the apron 16 (near the front end of the bowl) relative to the ground plus the maximum apron opening As to the ejector, it must move through a 66 angle between the solid line position and the dot-dot-dash line position in Fig. 10 about the pivot 34a and this requires a 59 angular travel of the ejector dump lever 72 about its pivot 72a. From a vector force diagram, it has been determined that a force of 15,600# is required at the roller 73 to lift the full load in the ejector 34.

Each hydraulic hoist has a 20" stroke with a piston having a 7%" diameter or a total cross sectional area of 49 sq. in. At full load, the following hydraulic pressures exist. In the bowl lift hoists 50 and 52, the hydraulic pressure required without considering starting inertia or friction is 49 sq. in.X20 In the apron lift hoist 51, the pressure required without considering the starting inertia or friction is In the ejector hydraulic hoist 70, the pressure excluding the starting inertia or friction is it should be realized that the friction load in dumping the ejector 34 is much higher than in either the bowl or the apron lift because of the wedging action.- The actual pressure required to dump the ejector is usually the highest of the three pressures. Both the apron and ejector moving mechanisms contain parts causing frictional drag whereas the bowl hoist is directly connected. Therefore, in actual practice, the hydraulic fluid pressure developed in the ejector and apron hoists and 51 is larger than the theoretical calculation shown.

Assuming the 20" stroke for each hydraulic hoist, the travel of the bowl and apron can be approached in another way. The travel of the lift link 62 was before given as 32 and proves to be the same here and the travel of the sheave end or pulley end of the lever 57 before given as 39" now comes out approximately the same =788 pounds per sq. in.

635 pounds per sq. in.

=620 pounds per sq. in.

It was previously pointed out that plate 74 can be of relatively short length due to the back and forth movement of roller 73 thereon during the ejection stroke, as shown in Fig. 10. With the above dimensions, the roller moves 14 toward pivot 34a between the solid line position and the dot-dash line position and then moves 5 to 6" back away from the pivot 34a between the dot-dash line and the dot-dot-dash line positions.

Although each of the hydraulic hoists shown as being a single acting hoist and being returned to its closed position by either the spring and the weight of the part being raised or the weight of the part alone, it should be understood that the hoists could be double acting hoists if desired. However, the single acting hoist is preferred since it requires only one pressure line and for other obvious reasons thoroughly set forth heretofore in the specification.

The afore-rnentioned dimensions and the structural parts of the lever type scraper set forth heretofore also give a good forward weight distribution of the scraper and its earth load onto the tractordrive wheels 21, 21 which is so vitally necessary for the maximum tractivc drive effort.

Although the front of the scraper pull yoke 22 is shown as being pivotally attachedto a tractor bya hitch 23,, other structures equivalent to the tractor and hitch could be used. The front of the pull yoke 22 could be securedsby hitch 23m an equivalent hitch to any other type wheeled supportingjframe, inaddition to the specific type shown as tractor 20 in the drawings, which supporting frame has steerable wheels with the wheels adjacent the hitch adapted to pass under the gooseneck arch of the pull yoke 22 during turning. The wheeled supporting frame not only supports the front of the pull yoke and scraper but also controls the direction of its movement. The motive power, now furnished by tractor 20, could be provided by a driving motor at the front or rear of the scraper or in any other desirablelocation Com monly; this type of scraper has thepull yoke connected by" a hitch to a two-wheel dolly, in the position of wheels 21, and a separate endless-track tractor or other motive power exerts the pull.

What we claim is: V j

1. In a'dig'ging and carrying scraper, a bowl having an open front and having an ejector'forf dumping the contents of said bowl, an apron for closing said open front, means for raising said bowl between lowered :and elevated positions, means for raising said apronnbctween positions closing and opening said open front, meansl for raising. said ejector between a lowered retracted position and anelevated dumping position, each of said means including an interchangeable single acting hydraulic hoist power unit in operative connection therewith forperforming the raising movement while the weight of the respectiye parts returns the apron or bowlor ejectorjtolits lowcred position when its respective hydraulic hoist power unitisfde-activated, the hydraulic hoist power units being operable independently so that the apron or the b owlor the ejector may be moved without moving the other two last-mentioned movable scraper parts, each hydraulic hoist power unit having the same length working stroke, said means for raising said bowl including two of said hydraulic hoist power units with each operatively connected to a motion transmitting means movable in response thereto with the last-mentioned means connected to said bowl for raising it at full load a short distance with great force, said means for raising said apron including a motion transmitting means movable in response to its associated hydraulic hoist power unit and operatively connected to said apron for raising said apron at full load about twice the distance at about twice the speed of said bowl raising movement and exerting about one quarter the lifting force required to lift said bowl, said means for raising said ejector including a motion transmitting means movable in response to its associated hydraulic hoist power unit and operatively connected to said ejector for raising it at full load at a speed varying approximately inversely with the load and with a force varying approximately directly with the load being moved during ejection and for accelerating its movement as it moves over approximately the entire distance from the retracted position to the dumping position when its associated hydraulic hoist power unit moves at a constant rate.

2. In a digging and carrying scraper, a yoke for attachment to a wheel supporting frame, a bowl comprising a bowl body having an open front and pivotally connected intermediate its ends to said yoke and having an ejector for dumping the contents of said bowl pivotally connected to said bowl body and forming bottom and rear walls for said bowl, an apron pivoted to said bowl adjacent the pivotal connections of said yoke for closing said open front, means on said yoke for raising said bowl between lowered and elevated positions, means on said yoke for raising said apron between positions closing and opening said open front, means for raising said ejector between retracted position and dumping position, each of said means including an interchangeable single acting hydraulic hoist power unit in operative connection therewith for power movement between positions in one, direction and for gravity return in the opposite direction, the hydraulic hoist power units each being operable independently sothat the apron or the bowl or the ejector may be moved without moving the other two last-mentioned scraper parts and each having the same length working stroke, each hydraulic hoist power unit having cylinder and piston members with a pivotal connection on each member, said means for raising said apron and bowl each including a lever pivoted at one end to said yoke and including one of said hydraulic hoist power 'units with one of its pivotal connections on said yoke and theother on its associated lever intermediate the opposite ends, thedistal end of the bowl raising lever being operativelyconnected'to saidbowl body, the distal end of the apron raising lever having movement multiplying means operatively connected to said apron for causing it to move at a more rapidrate and over a greater distance than said last-mentioned distal end, said means for raising said ejector including a leverl having at one end a pivotal connection fixedwithrespect to the bowl body and having its other end adapted to make a relatively moving contact withtheoutside surface of said ejector, the hydraulic hoist power*unit for moving said ejector having one of its pivotal connections fixed with respect to the bowl body and the other intermediate the opposite ends of said ejectordever; whereby the ejector accelerates over approximately its entire movement from retracted to dumping position when the movement caused by its associated hydraulic hoist power unit is at aconstant rate. I

3; In a digging and carrying scraper having a scraper bowl Wih an open front, an apron connected to said bowl for relative'movement between positions closing or opening' said open front, a pull yoke having a hitch member at its front end forpattachment to a tractor between its rear wheels for moving saidscraper, said pull yoke having rearwardly extending side walls and having a transversely extending torque tube secured to the rear of said walls to extend laterally on each side thereof and having means connecting said torque tube to said bowl for relative movement therebetween; the combination wherein said pull yoke walls diverge in the rearward direction and form a gooseneck portion arched upwardly sufficiently for clearing the rear wheels of said tractor during turning, a plurality of hydraulic hoists with each having an approximately vertical axis and being located at the rear of said pull yoke between said diverging walls and operatively connected to said bowl and apron for raising said bowl and for moving said apron between said closing and opening positions, each hydraulic hoist having cylinder and piston members with one of said members being pivotally mounted to the lower rear portion of the gooseneck portion, said operative connections including a plurality of levers pivotally connected to said gooseneck portion near its upper portion and extending rearwardly in the direction of sight of the operator on said tractor looking toward said bowl, each lever being pivotally connected to the other of said members of its associated hoist, one lever having rotatably mounted at its rearward end a pulley over which a run of cable extends between fixed connections respectively to said yoke and apron, another of said levers being operatively connected to said bowl by a rigid link extending between said bowl and the rearward end of said other lever, whereby operation of said hoist will cause said apron to move upwardly to a greater extent at greater speed than said bowl.

4. In a digging and carrying scraper, as set forth in claim 3, wherein said levers are inclined downwardly from their pivotal connection to said gooseneck during loading so that they do not interfere with the rear view of the operator above the pull yoke.

5. In a digging and carrying scraper having a scraper bowl with an open front, an apron connected to said bowl for relative movement between positions closing or opening said open front, a pull yoke having a hitch member at its front end for attachment to a tractor for moving said scraper, said pull yoke comprising a pair of diverging arms rearwardly extending from said hitch member, a transversely extending torque tube secured to the rear of each arm and extending laterally on each side thereof, and means connecting said torque tube to said bowl for relative movement therebetween; the combination wherein said torque tube has a cutout formed by cutaway portions in the tube walls between said diverging arms, approximately vertically extending hoists in said cutout for raising said bowl and for moving said apron between said closing and opening positions, said cutout spaced forwardly from the rear wall of said torque tube, a wall secured to the torque tube walls surrounding said cutout for housing said apron and bowl hoist moving means, at least one sight opening in said last-mentioned wall, whereby the tractor driver can see through said opening into the housing in said cutout for observing the action of the'hoists and can see between said hoists back into the bowl while loading and dumping and can see the bottom "of the bowl under the torque tube while loading, dumping and hauling.

6. In a digging and carrying scraper, as set forth in claim 5, wherein each hoist is pivotally mounted to said yoke with said plate preventing dirt entry and jamming of the pivotal hoist movement.

7. In a digging and carrying scraper, a scraper bowl having a bottom and back and spaced apart side walls and an open front, an apron connected to said bowl for relative movement between positions closing or opening said open front, a yoke having a hitch member for attachment to a wheeled supporting means at its front end for moving said scraper, said yoke comprising a portion having outer side walls diverging in the rearward direction, a transversely extending torque tube secured to the rear of said first-named portion bridging the space between said diverging walls and extending laterally on each side thereof, said torque tube being box beam in form and having a cut-out formed by cut-away portions in its top and bottom walls between said diverging walls for housing means for raising said bowl and for'moving said apron between said closing and opening positions, said cut-out being spaced forwardly from the rear wall of said torque tube, a surrounding wall secured to the torque tube walls surrounding said cut-out for housing said apron and bowl moving means and diverging in the up ward direction to permit pivotal movement thereof, two arms, each of said arms secured at its forward end to one of said laterally extending portions of said torque tube and at its rearward end pivotally attached to one of said bowl side walls, said arms and torque tube and diverging portion being each formed of box beam construction for providing a continuous rigid box beam between the hitch member and the pivotal connections of the arms with the bowl sides.

References Cited in the file of this patent UNITED STATES PATENTS 2,154,503 French et a1. Apr. 18, 1939 2,227,433 Berner Jan. 7, 1941 2,252,763 French Aug. 19, 1941 2,304,076 Davidson Dec. 8, 1942 2,304,527 Armington et al. Dec. 8, 1942 2,345,313 Armington et al Mar. 28, 1944 2,406,826 French et al Sept. 3, 1946 2,529,848 Murray Nov. 14, 1950 2,567,118 Murray Sept. 4, 1951 2,573,765 Gustafson Nov. 6, 1951 2,650,440 Quartullo Sept. 1, 1953 2,662,312 Kadz Dec. 15, 1953 2,674,815 Adams Apr. 13, 1954

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