US2478747A - Front end tractor implement - Google Patents

Description

Aug 9, 1949. T. M. DEAL ErAL 2,478,747

FRONT END TRACTOR IMPLEMENT Filed Aug. 3, 1945 9 Sheets-Sheet 1 Allg- 9, 1949- T. M. DEAL ETAL 2,478,747

FRONT END TRACTOR IMPLEMENT ATTORNEY Aug. 9, 1949.`

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FRONT END TRACTOR IMPLEMENT T Filed Aug. 5, 1945 9 Sheets-Sheet 6 ATTRIYEY Aug- 9, 1949 T. M. DEAL ETAL 2,478,747

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T. M. DEAL ETAL FRONT END TRACTOR IMPLEMENT Filed Aug. 3, 1945 9 Sheets-Sheet 9 afmw Patented Aug. 9, 1949 FRONT END TRACTOR Troy M. Deal, Walter Baker, and Henry B. Duttweiler, Cedar Rapids, Iowa, assignors to Link- Belt ipeedei' Corporation, a 'corporation of l Illing Application samt 3, 1945, serial No. am

l This invention relates to front end implements for tractors of the crawler or wheel supported types, and deals more particularly with load handling implements, such as shovels, which are prefabricated as complete, self-contained units ready for mounting on, or to be attached to, general purpose tractors, such as the regular standard products of tractor manufacturers.

It has been the practice to mount' shovels on the front ends of tractors in such a manner that the movements of the buckets or scoops. between loading and dumping positions, are limited to a vertical path that usually is defined by xed guide rails or slides. Consequently, the entire tractor assemblies must be m'oved, usually by backing and turning, to properly position the buckets or scoops for dumping their loads.

With this type of shovel mechanism, the weight of the bucket, the load` carried thereby, and the mounting mechanism for the bucket is applied to the front end 'of the tractor, with the result that the center of gravity of the entire unit is shifted forwardly a substantial distance frozn the location of the center of gravity of the tractor when considered by itself. This displacement of the center of gravity materially reduces the stability of the entire machine and lessens the traction that can be obtained with the traction or travel mechanism of the tractor.

It is the primary object of this invention to provide front end shovel mechanism which is adapted to be prefabricated as a complete, unitary assembly in readiness for easy attachment to general purpose tractors of standardmakes, the said shovel mechanism being so constructed that its bucket or scoop may be loaded while arranged in its digging position in front of the tractor, as a result of forward movement of the latter, and may be dumped at any desired loca-tion throughout an arc of approximately 180 without moving the tractor.

Another important object of the invention is to provide a front end shovel attachment for tractors in which the bucket is supported for horizontal swinging movements relative to the in which the bucket is connected to the outer end of an arm that in turn is supported for -universal movements by a mast assembly that projects upwardly from substantially the center of the tractor.

24 Claims. (Cl. 214-132) is to provide a. front end shovelv for tractors A in which the bucket is lowered into a position in advance of the tractor, so that the crowding motion required to load the bucket is accomplished by advancing the entire tractor through its travel mechanism, and so that the thrust from the digging action is applied to the undercarriage of the tractor by the base frame of the shovel mechanism; and in which the loaded bucket is hoisted to a sumcient height to clear the power plant of the tractor when it may be swung to either side of the tractor for dumping.

A still further important object of the invention is the provision of hydraulic means for effecting hoisting and swinging movements of the bucket through manipulations of a bucket supporting arm.

Another object of the invention is to provide pivotal connections between the bucket and the outer end of the bucket arm so that the bucket may assume loa'd carrying and dumping positions relative to said arm, and employ hydraulically operated latches for releasing the b et from its carrying position to effect dumping.

A further object of the invention is to provide means for utilizing the downward movement of the bucket arm, in returning the bucket for loading, to effect pivotal movement of the bucket relative tothe outer end of said arm for returningthe bucket from its dumping position to its loading position.

Still another object of the invention is to provide thrust members at the iront end of the shovel base frame by means of which the thrust resulting from digging action of the bucket may be deliveredy to the under-carriage of the tractor through said shovel base frame, and independently of the bucket arm, the said thrust members being so shaped and arranged that they will cooperate with the bucket when positioned for digging at any desired elevation which falls within a vertical range that extends from a lower limit which is several inches below the ground level to an upper limit which may be approximately two feet above the ground level.

A s-tillfurther object of the invention is to provide a front end shovel for standard tractors of the crawler or wheel supported type in which the bucket is so positioned and hydraulically actuated that the tractor equipped therewith may be used veryv eiectively as an implement for cutting and maintaining a grade, and for other similar earth working operations.

Other objects and advantages of the invention In the accompanying drawings forming a part of this specification and in which like numerals are employed to designate like parts throughout the same,

. Figure 1 is a side elevational view of a tractor with a complete front end shovel assembly attached thereto,

Figure 2 is a top plan view of the combination tractor and front end shovel combination illustrated in Fig. 1,

Figure 3 is a side elevational view that is provided to better illustrate the hydraulic system employed for actuating the bucket portion of the shovel assembly, said bucket being illustrated in a partially hoisted position,

Figure 4 is a top plan view of the hydraulic system illustrated in Fig. 3,

Figure 5 is a detail, vertical sectional view provided to illustrate the latchingA mechanism that is employed for holding the bucket in its digging and load carrying position with respect to the bucket arm, and for releasing the bucket to effect dumping of its load,

' Figure 6 is a front elevational view oi the tractor with the bucket arm hoisted to approximately its upper limit of movement and with the bucket released to eiect dumping. In viewing this ligure. it is to be remembered that the bucket usually is swung into a position at one or the other side of the tractor for dumping the load,

Figure 7 is a detail side elevational view of the outer end portion of the bucket ann with the bucket unlatched and occupying its load dumping position,

Figure 8 is a. detail vertical sectional view, taken transversely of the tractor, of the mast assembly that is employed for supporting the bucket arm for universal movements,

Fi-gure 9 is a, detail, top plan view of the mast assembly illustrated in Fig. 8, Y

Figure 10 is a detail, vertical sectional view of mechanism employed for returning the bucket to its loading position, relative to the bucket arm, during lowering movement of said arm,

Figure 1l is a detail elevational view of the bucket when viewed from its inner or rear face,

Figure 12 is a fragmentary horizontal sectional view of the bucket, and taken on line I2--I2 of Fig. 1,

Figure 13 is a detail, rear elevational view of the hydraulic system employed for actuating the bucket and its arm,`

Figure 14 is a fragmentary view, partlyl in top plan and partly in horizontal section, illustrating the portion of vthe hydraulic system that functions to effect horizontal swinging movements of the bucket and its supporting arm, and

Figure 15 is a diagrammatic view of the swing and hoist valves which are illustrated in certain of the preceding figures.

In the drawings. wherein for the purpose of illustration is shown the preferred embodiment of this invention, and first particularly referring to Figs. 1 to 4 inclusive and 6, the reference character A designates in its entirety the power plant of any general purpose, standard make of tractor. The illustrated tractor is provided with crawler traction mechanism B, but it ls to be understood that the shovel mechanism that is to be described just as readily can be applied to a vtractor that is equipped with traction wheels instead of the illustrated crawler mechanism.

extend longitudinally of the latter.

The shovel mechanism-consists of a complete. prefabricated assembly that can be handled as a unit for mounting on any general purpose, standard make of tractor. For that reason, the shovel mechanism includes a base frame that is made up of two partially overlapped, channel iron beams il and Ii which are adapted to oe located on each side of the tractor selected for mounting the mechanism. The overlapped ends of these beams are suitably connected by welding and the beams on each side of the tractor The front ends of the beams Il are connected to upstanding angle irons I1. Extending rearwardly from the upper ends of these angle irons I1 are longitudinal 'bracing irons Il. The inner or rear ends of these bracing angle irons i8 are suitably connected -to a fabricated, rmast mounting' Il, which will be described more in detail at a later point. This mast mounting is suitably supported on the base fra-me beams il.

The base frame of the shovel mechanism is best illustrated in Figs. 1 and 3 as being suitably attached to the under-carriage 'of the selected tractor by means of the mounting brackets 20, 2i and 22. No attempt has been made to disclose in detail the exact shapes of these brackets 20 to 22, or the exact manner in which they are fastened to specific portions of the under-carriage of thel tractor because these attachment brackets, naturally, will be varied in shape, size, and location to accommodate the structural details of tractors manufactured by different companies.

Bridging the space between and supported on the rear end portions of the base frame beams I! and extending laterally on opposite sides thereof is a housing 22 that is employed for enclosing a portion of the hydraulic system which is utilized to actuate the bucket and its arm. Forwardly of this housing is an operators platform 24. An operators seat 2l is positioned centrally of and supported by the housing 2l. The various controls for the tractor have not been illustrated but it is to be understood that they are properly associated with the operators seat 25 so that the person occupying this seat can control the tractor as well as the shovel mechanism.

The previously referred to fabricated mast mounting Il is best illustrated in Figs. i, 2, 8, 9 and 14. It includes a transverse bottom plate 2l which is suitably welded, at its opposite ends, to the top anges of the side frame beams i5. Side plates 21 are welded at their lower edges to the top flanges of the frame beams Il, as best illlustrated in Fig. 8. These side plates converge upwardly and are connected at their upper edges by the top plate 2l. A second bottom plate 2i is arranged in parallelism with the bottom plate 28 and is spaced vertically thereof. The side edges of this upper plate 2! are suitably welded to the inner faces of the two side plates 21. Perpendicular web members 30 are secured in place and function to reinforce the side plates 21.

The two bottom plates 2l and 2! are cut away, or provided with openings, to receive the sleeve Il which is welded, or otherwise suitably secured, to the margins of the openings that are formed in the plates 26 and 29. 'I'he sleeve Il is illustrated as being provided with a bronze bushing at 32 to act as a radial bearing for the lower end of the rotatable mast post 33. It is-to be understood, however, that a ball or roller anti-friction bearing may be substituted, if desired, for this lower post bearing.

combined .thrust and radial bronze bearing as-` sembly 3,4. This latter bearing rotatably supports the upper portion of the mast post 33. This lat,-

ter bearing, also, may take the form of a roller or ball bearing structure if desired.

By referring to Figs. 8 and 9, it will be seen that the upper end portion of the rotatable mast post 33 has suitably secured thereto the box structures 35 that project. laterally in opposite directions. Each one of these box structures is made up of four plates 36, 31, 38 and 39. These plates are welded together at their adjacent, longitudinal edges. The bores of these boxes 36 are employed for housing the blocks 40 and 4|. The blocks 40 are fastened in the outer end portions of the boxes 36 by welding. The blocks 4| are welded in the bores of the boxes 35. Pins 42 pass through and secure to the boxes 35` the inner end portions of the shafts 43 that project beyond the outer ends of said boxes.

Figs. 1, 2, 8 and 9 disclose parallel bracket arms -or plates 44 as being connected atl their inner,

lower corner portions to the boxes 35 by welding. These bracket arms or plates are clearly illustrat'ed in Figs. 1, 2 and 9 as extending laterally of the rotatable mast post at right angles to the shafts 43. Top plates 45 and bottom plates 46 are welded at their longitudinal edges to the top and bottom edges of the arms 44 to form flanges for these arms. The plates 45, additionally, are welded to the upper extremity of the rotatable mast post 33, as best illustrated in Fig. 8.

A bucket arm, designated in its entirety by the reference character 41, is illustrated in Figs. 1, 2, 6 and 8 as being jour-naled on the projecting end portions of the two shafts 43. This bucket arm includes the two branches 48 and 49 that are so shaped as to provide downwardly curved end portions 48a and 49a. The inner ends of these branches 48 and 49 are suitably welded to an arched branch 50 which is arranged substantially at right angles to the main body portions of the branches 48 and 49. Fig. 8 shows the two extremities of the arched branch 56 as having bronze bearings 5| for receiving the projecting end portions of the two stub shafts 43.

From the description so far presented of the mast assembly and bucket arm, it will be seen that the bucket arm may be hinged or pivoted vertically about the stub shafts 43 and the bucket arm may be lswung horizontally in opposite directions as a result of rotation of the mast post 33. The horizontal swinging of the bucket arm, of course, can only occur While the branches 48 and 43 of the arm are located above, or at a higher level than, the power plant A of the tractor and the shovel frame portion that is formed by the angle iron members I1 and |8.

Figs. l, 2, 5, 6, 7, 11 and l2 illustrate the bucket 5| that is pivotally connected to the outer extremities of the branches 48 and 49 of the bucket arm 41. Each one of the bucket arm branches carries a transverse pin 52 at its other extremity. At each side of the back of the bucket 5I there are provided two lugs 53 and 54. These lugs are formed with elongated openings 55 that receive the projecting ends of the pins 52. These elongated openings 55 and the pins 52 cooperate to provide a pivotal connection between the bucket 6| and the bucket arm branches 48 and 49 and, also, provide for a relative shifting movement, or

displacement, of the bucket relative to the said arm branches. The reason for providing this shiftable or relative movement connection will be explained at a later point.

Additional lugs 56 are fastened to the back wall of the bucket 6| and are arranged in parallelism with and inwardly of the lugs 54. Rollers 51 are rotatably supported by the lugs 54 and 56. A suitable length of angle iron 68 is illustrated in Figs. 11 and 12 as being fastened to the back of the bucket 6| to lie between the innermost lugs 66.

Figs. 1, 2, 6, 11 and 12 illustrate thrust plates 68 that are located on opposite sides of the front end of the tractor. These thrust plates are suitably fastened to the under-carriage of the tractor, as at 68 in Fig. l, and to the front end portions of the base frame beams I6. These thrust plates are provided with front edge flanges 6| which are slightly hooked or curved at their lower ends 62.

Thrust plates 59 are longitudinally in alignment with the rollers 51 carried by the back of the bucket and theilanges 6| of the thrust plates are intended to be engaged by the rollers 51 when the bucket is caused to shift rearwardly or inwardly as a result of digging action to load the bucket. It will be seen, therefore, that the thrust developed during digging of the bucket into a bank or pile of material, or while performing Lother material moving operations, will be applied to the front edges of the thrust plates 59. Any

vertical movement of the bucket 5'|, while it is displaced inwardly to place the rollers 51 into engagement with the thrust plate anges 6|, willl caus'e the rollers 51 to roll over these flanges.

By considering the disclosures of Figs. 1 and 6, it will be seen that the rollers 51 will engage the thrust plate flanges 6| when the bucket is positioned for digging at any desired elevation falling within a vertical range that will have as its bottom limit the bucket position illustrated in Fig. 1 and will have as its top limit a bucket position in which the rollers engage the upper end portions of the thrust plate flanges 6|. In the bottom limit position illustrated in Fig. 1, the forward or cutting edge of the bucket is located several inches below the lground level. In the upper limit position, the cutting edge of the bucket will be located approximately two feet above the ground level. It will be appreciated that this range of bucket digging positions can be varied, as desired, by employing thrust plates with different length front flanges 6|.

The front edge of the bucket 5| is caused to dig into the material that is to be loaded into the bucket by advancing the entire tractor by means of its travel mechanism. By taking the thrust, that is developed by the digging action, on the thrust plates 59, and through these thrust plates on the base frame of the shovel mechanism and the under-carriage of the tractor, no digging thrust is applied to the bucket arm 51 and the rotatable mast post 33.

Figs. 1, 2, 5, 6 and '7 disclose the mechanism for holding the bucket 5| in its digging and load carrying position relative to the bucket arm 41.

Extending across the upper, rear edge portion of the bucket is an angle iron 63 which is provided in its upper flange with the two latch receiving openings 64 which are lined up longitudinally of the tractor with the bucket arm branches 48 and 49. A wear plate 65 is associated with one a pivoted latch 61.

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Each bucket arm branch 40 and 40 haaruitably attached thereto a pair of spaced..triangu larly shaped .bracket plates 6l. The latches 01 are pivotally connected to these plates l by the pins 00 so that the latches lie between the plates 00. Each one of these latch members 81 is provided with an operating arm 1I. A spring 1| is attached at one of its ends to each one of these latch operating arms 10 and at its other end to a lug 12 carried by one of the plates Il. These springs 1i load the latch members t1 in the proper direction to cause them to engage and hold the bucket in its digging and load carrying position.

The latch operating arms 10, also, have connected thereto the hydraulically operated, expansible, trip cylinders 13.

These trip cylinders 13 are best illustrated in Figs. 1, 3, 4 and 5. Their inner ends 14 are suitably connected to the associated plates 60 to permit the cylinders to operate the latches 01, to trip the bucket 5| for dumping its load, whenever suillcient fluid pressure isv applied to the expansible trip cylinders 13 to cause these cylinders to pivot the latches 01. Fluid supplying tubes 1i are connected to the inner ends 14 of the trip cylinders 13 and extend longitudinally of the respective bucket arm branches 48 and 40 and then laterally inwardly to be connected to the T- coupling 16, see Figs. 1, 3 and 4. From this coupling flexible tubing 11 extends downwardly through the hollow bore of the rotatable mast post 33 to the level of the base frame of the shovel mechanism. The tube 11 then extends horizontally beneath the platform 24 and upwardly through the casing 23 for connection with the T-coupling 10 that is connected in a iiuid return line 19. This fluid return line is illustrated in Figs. l, 2, 3, 4, and 13 as being connected to the trip cylinder controlling valve 00 that has its second opening connected to theiluid supply tank Il by the coupling 02 and .the nipple 83. The operation of this latch tripping control valve 00 in connection with the remainder. of the hydraulic system will be described more in detail at a later int. I pc'Figs 1 to 4 inclusive, 6 and 7 disclose sprin means for limiting the movement of the bucket 5| into its dumping position and for absorbing the shock resulting from the stopping of the pivotal movement of the bucket. This mechanism consists of a spring 05, on each side of the bucket, Awhich is connected at one end to the lug 00 attached to the adjacent bucket side. The remaining end of each one of these springs 05 is connected by a short length of chain 81 to a laterally projecting lug 88 that is attached to the outer side of the associated bucket arm branch 40 or 49.

The mechanism so far described in connection with the operation of the bucket 5| provides for the holding of the bucket in its digging and load carrying position, the tripping of the bucket to effect dumping of the load, and the stopping of the bucket at the proper load dumping position. The mechanism next to be described performs the operation of returning the bucket from its dumping position to its latched digging and load carrying position as a result of downward movement of the bucket arm 41.

By referring to Figs. 1, 2, 6 and 10, it will be seen that the bracket arms 44 have mounted thereon a fabricated platform 89 that straddles the space between the said bracket arms. Supported on this platform 89 are the brackets 90 and Il. The upper end portion of the bracket 0l hal suitably fastened thereto a plate l2 which acts as a mount for the collar 0I. Supported in this collar is one end of the shaft 04. The pin It is employed for fastening the shaft 04 to the collar to prevent either angular or axial movements of the shalt. The remaining end of the shaft is supported by the collar 00 that is suitably fastened to the second upstanding bracket Il.

An end plate or disc 01 is Journaled on one end portion of the-shaft 04 by the bronze bearing Il. A tubular sleeve or housing 90 has one of its ends suitably flanged and fastened to the disc or end plate 01.- The remaining end of this tubular housing or sleeve Il is welded to a second end plate or disc |00. This end plate or disc |00 is suitably welded to the bearing sleeve |0| that is provided with abronze bearing and is journaled on the adjacent portion of the stationary shaft I4.

A coil spring |02 is enclosed within the housing or sleeve l! and has its end |03 fastened to the bearing sleeve |0| that rotates with the housing or sleeve 99. The remaining end of this spring is fastened by the pin |04 to the supporting block |05 and the associated portion of the stationary shaft 94.

The disc or end plate |00 has suitably fastened thereto a brake drum |06. The open side oi' this drum is closed Vby the stationary cover |01. A conventional brake shoe mechanism |00a will be positioned within the brake drum |08. It is intended that the brake shoes of the mechanism |0Ba be actuated for engaging the inner peripheral surface of the brake drum |06 by any suitable pull-cable or rod actuating mechanism |01a, or by any desired form of hydraulic mechanism, not shown.

A cable sheave |00 is attached to and mounted on the exterior of the sleeve or casing 99 so as to rotate with the latter. An appropriate length of cable |09 is suitably anchored at one end to the sheave |08 and wound a desired number of times therearound.

This cable |09 extends longitudinally of the bucket arm 41 and is attached at its outer end to the pair of lugs ||0 fastened to the angle iron Il that has been previously referred to as being attached to the upper edge portion of the rear wall of the bucket 5|.

Whenever the bucket 5| is located in front oi' the tractor and at an elevation that positions the cable attaching brackets I0 below the level of the shovel frame that is formed by the angle members |1 and Il, the cable |09 will engage the roller III that is rotatably supported by a rod mounted at its ends in the brackets H2. These brackets are supported by the shovel attachment frame that is formed by the angle members |1 and Il.

The operation of this bucket returning mechanism -will be described as follows.

The spring |02 should always be tensioned, or wound up, so as to take Aup any slack that occurs in the cable |08 as a result of the bucket 5| being moved upwardly from the position it occupies in Figs. 1 and 2. Consequently, the cable .I 0l will always be maintained taut by the spring |02.

When the bucket 5| is hoisted and tripped to eiiect dumping, the bucket will occupy the position illustrated in Figs. 6 and 7 with reference to the bucket arm 41. The cable |05 is pulled olf of or unwound from-the sheave |00, to the desired extent, by this dumping movement of the bucket 5i. If the bucket has been dumped while the bucket arm 41 is positioned at either side of the tractor, the bucket arm is swung around until it is properly 'positioned over the tractor so that it can be lowered with the bucket arm branches 48 and 49 lying on opposite sides of the tractor power plant A and the front portion of the shovel attachment frame. With the bucket arm properly positioned for lowering, the arm is allowed to move downwardly. The brake shoes of the mechanism |06a are applied to the brake drum |05, at the proper time during the downward movement of the arm 41 and its bucket 5|. This braking of the sleeve 99 and its attached cable sheave |08 against angular movement causes the cable |09 to exert a pull on the upper back portion of the bucket. This pull causes the bucket to swing upwardly and inwardly, from the position illustrated in Figs. 6 and '7, until the latches 61 will be permitted to engage the bucket for fastening the latter in its digging and load carrying position. After the bucket is thus latched, the brake shoes are recased from engagement with the brake drum |06 so that further downward movement of the bucket, and the bucket arm 41, will be accompanied by unwinding of the cable |09 from its sheave |08.

The brake shoe mechanism |a, also, can be employed for controlling the dumping action of the bucket. By properly applying the brake mechanism during the dumping movement of the bucket, the rate of discharge of the material can be controlled. The operator thus can better distribute the spilled material into trucks and can lessen the impact load on the truck and the shovel mechanism.

The bucket arm 41 is actuated to effect hoisting and lowering of the bucket 5| by a hydraulic motor which now will be described in connection with Figs. 1 to 4 inclusive, 6 and 8.

The hydraulic cylinder ||3 is piviotally attached to the outer end portions of the bracket arms 44 by means of the split clamping collar ||4 and the stub shafts ||5 which are carried by the opposite halves of the collar. These stub shafts are journaled in openings I I6 formed in the extremities of the bracket arms 44.

The hydraulic cylinder ||3 is provided with an appropriate piston, not shown, and t'he rod |1 projects from the inner end of the cylinder and is pivotally connected to the yoke-shaped branch 50 of the bucket arm 41 by means of the pin I8 and the lugs H9.

The outer end of the hydraulic cylinder ||3 has connected thereto a fluid pressure supply line |20 that is connected at its remaining end to the .swivel coupling |2| positioned at the open upper end of the rotatable mast post 33. This coupling is mounted on the non-rotatable uid supply pipe |22 that extends axially of the bore of the rotatable mast post 33 to emerge from the lower end of the latter. The supply pipe |22 is illustrated in Figs. 1, 3, 4 and 13 as extending laterally of the bottom of the mast post 33 and then rearwardly along one of the shovel base frame beams |5 for connection at its inlet end with a fluid flow control valve |23. The manner in which this valve |23 controls the flow of pressure fluid to the outer end of the cylinder ||3 will be described more in detail at a later point inv referring to the entire hydraulic system.

It will be appreciated that when pressure fluid is admitted to the pipes |22 and |20, pressure is built up in the outer end portion of the cylinder ||3 and this pressure will effect movement of the piston, not shown, sof the cylinder to cause the piston rod |1 to move outwardly of the inner end of the cylinder. 'I'his outward movement of l0 the piston rod applies force to the bucket arm branch 50. This pressure, or force, will cause the bucket arm to be plvoted relative to its supporting shafts 43, that are carried by the upper end portion of the rotatable mast post 33. \Eluid pressure is applied to the cylinder l I 3 until the bucket arm 41 has been raised to the desired elevation. The pressure fluid then is locked in the cylinder ||3, by proper operation of the control valve |23, and the bucket arm 41, with its bucket 5|, then may be swung in either direction by rotation of the mast post 33. When the bucket 5| and its arm 41 again are to be lowered, the pressure fluid is withdrawn from the cylinder ||3 and the weight of the bucket and its arm will cause the piston to be moved inwardly of the cylinder ||3.

From the above description of the operation of the hydraulic motor for raising and lowering the bucket arm 41, it will be appreciated that uid pressure is applied only to one end of the cylinder I3. The remaining end of this cylinder will be provided with a suitable vent or breather opening, not shown. to prevent the building up of either positive or negative pressure on the inner side of the piston.

It will be appreciated that pressure fluid could be applied to the upper end of cylinder |I3 if such a procedure is desired. Application of presl sure fluid to the upper side of the piston in cylinder ||3 would cause the bucket 5| and its arm 41 to be moved downwardly and would overcome the need for relying on the weight of the bucket and its arm to effect this movement. The application of pressure fluid to move the bucket downwardly, also, could be employed for forcing the bucket downwardly into the material being handled to assist the digging action that is otherwise dependent on the forward movement of the tractor. Plug |22a in Fig. l5 closes aport in valve |23 that can be used when uid is to be delivered tothe upper end lof cylinder I3.

The mechanism employed for effecting swinging movement of the bucket 5| and its arm 41, by means of the rotatable mast post 33, is best illustrated in Figs. 3, 8, 13 and 14. This mechanism will be described by referring to these figures.

The rotatable mast post 33 has suitably fas- `tened to its lower end portion a sprocket wheel |24 over which is trained a suitable length of roller chain |25. rIfhis chain is further trained over the two idler sprockets |26 and then over the two drive sprockets |21 that are rotatably carried by the opposite ends of the hydraulic motor operated piston rod |28. The 'opposite ends of the length of roller chain |25 are anchored by-the adjustable bolts |29 to the portions |30 of the hydraulic cylinder |3|. The `piston rod |28 that extends axially through the cylinder |3| has mlounted thereon a double acting piston, not

shown. It will be appreciated that reciprocation of this piston within the cylinder |3| in opposite directions will cause the mast post 33 to be rotated in opposite directions through the medium of the roller chain |25.

Pressure fluid is selectively fed to the opposite ends of the cylinder |3| through the two supply pipes |32 that extend to and are connected with the control valve |33. The operation of this control valve |33, for effecting rotation of the mast post 33, will be described more in detail when the complete hydraulic system is referred to.

The complete hydraulic system will be described in connection with the disclosures provided by Figs. 1 to 4, inclusive, 13, 14, and 15. The oil reof the casing or housing 23. The oil is withdrawn from this tank. by means of a dip tube that is not disclosed, through the pipe line |34. This pipe line extends downwardly through the casing or housing 23, as is best illustrated in Fig. 13, to the level of the base frame beam I and then extends horizontally and longitudinally of the tractor to be connected to the pump |35 that is located at the front end of the tractor power plant A. This pump is driven by the crank shaft, not shown, of the power plant. From the discharge side of the pump |35, the fluid ilows through the pipe line |34 which extends longitudinally of the shovel base frame member I5 and is connected at its rear end to the relief valve |31. This relief valve A normally is conditioned so that the oil flows therethrough and leaves the same by means of the pipe line |33. This latter pipe line directs the flow of oil into the previously referred to control valve |33 for the mast swinging hydraulic cylinder |3|. If the valve 33 is not conditioned to feed oil to either end of the cylinder |3 the oil flows through the valve |33 to the valve |23. This valve |23 controls the operation of the shovel arm hoist cylinder ||3 and if this valve is not conditioned to deliver oil to this cylinder, the oil ilows through the valve |23 and discharges therefrom through the return pipe line 19, which has been previously referred to. This pipe line 19 carries the oil back to the supply tank 0| by way of the bucket latch trip control valve 80, the coupling 32 and the nipple 33.

The relief valve |31 is set to relieve the system when the maximum operating pressure prevails therein. A pressure of 1000 pounds per square inch has been established as this maximum operating pressure. either the piston for the hoist cylinder I3 or the piston for the swing cylinder |3| is prevented from partaking of further movement, such as when it reaches its limit of travel in an operative direction. When -this maximum pressure is reached, the relief valve |31 is actuated and functions to cause the oil to flow through its bottom coupling member |39 and from this member through the pipe line |40 which extends to the remaining branch of the previously referred to coupling 32. This coupling is connected to the supply tank Il by the nipple 33 and the by-passed oil is thus returned to the supply tank.

It previously has been stated that the valve |23 controls the flow of pressure iluid to the hoist cylinder ||3. This valve |23 is illustrated in Figs. 3, 4, 13 and 15 as being provided with two operating stems |4| and |42. The several figures show these two stems in neutral positions. By referring to the diagrammatic disclosure of Fig. 15, it will be seen that valve stem |4| extends into what will be termed a cut-off valve chamber |23a for operative connection with the doublepiston cut-off valve member |4|a. This same figure shows the valve stem |42 extending into the control valve chamber |2312 for operative connection with the double-piston control valve member |42a.

The two valve stems |4| and |42 are pivotally connected to the ends of the centrally pivoted lever |43 so that movement of this lever will cause the valve members |4|a and |42a to be moved in opposite directions. In Figs. 3, 4 and 13, the lever |43 is illustrated as being operatively connected by the train of link and lver elements |44 to the hoist control lever |45 that is conveniently located This pressure is reached when.

to an operator occupying the seat 25. The condensed disclosure provided by Fig. l5 shows the hoist control lever |40 as being directly connected to lever |43.

The valve |33 has been described as controlling the ow of the pressure fluid into the pipelines |32 that lead to the opposite ends of the swing cylinder |3|. This valve |33 is provided with the two operating stems |46 and |41. The several figures show these two stems in their neutral positions. Byfreferring to Fig. 15 it will be seen that valve stem |46 extends into cut-off valve chamber |33a for operative connection with the doublepiston cut-olf valve member |46a. This same figure shows the valve stem |41 extending into the control valve chamber |33b for operative connection with the double-piston control valve member |41a.

The two valve stems |46 and |41 are pivotally connected to the ends of the centrally pivoted lever |48 so that movement of this lever will cause the valve members |46a and |41a to be moved in opposite directions. In Figs. 4 and 13, the lever |48 is illustrated as being operatively connected by the train of link and lever elements |49 to the swing control lever |50 that is conveniently located to an operator in seat 25. The disclosure provided by Fig. 15 shows the swing control lever |50 as being directly connected to lever |48.

It will be understood that the casings of valves |23 and |33 are provided with a proper number and arrangement of ports and ducts for properly connecting the various valve chambers |23a, |230, |33a, and |33b with each other and with the supply pipe line |33, the return pipe line 19, the hoist fluid supply pipe line |22, and the swing fluid supply pipe lines |32. For the purpose of simplification, these ports and ducts are illustrated in Fig. 15 in a diagrammatic manner and are identifled by the reference characters A to L. These reference characters will be employed in describing the operations of the valves 23 and |33.

The operation of valves |23 and |33, in effecting hoist and swing movements of the bucket arm 41 and the bucket 5|, now will be described by referring principally to the disclosure of Fig. l5.

When the hoist control lever |45 and the swing control lever |50 are in their neutral positions, as illustrated in Figs. 1 to 4 inclusive, 13 and 14 as well as Fig. 15, the various valves Illa. I42a, |43a and |41a are so arranged that the pressure huid will ilow from the supply pipe line |3| through the ducts A, B, and C and through the valve chambers |33b, |33a, and |23a to the port D and through this port to the return pipe line 13.

When the bucket 5| and its arm 41 are to be hoisted into a position where they can be swung to either side of the tractor for dumping the bucket, the hoist control lever |45 is moved counterclockwise. as viewed in Fig. 15. This movement of the hoist control lever |45 causes the port H, of valve chamber |23b, to be uncovered by the associated valve piston of member |4211. Pressure iluid then will ow from the supply line |33 through the duct A and the valve chamber |23b to the port H and through this port to the hoist fluid supply pipe line |22. This movement of the hoist control lever |45 has caused one of the pistons of valve |4|a to close the port D so that the pressure uid cannot be delivered to the return pipe line 19.

. After the bucket 5| and its arm 41 have been hoisted to the desired elevation for swinging, the control lever |45 is returned to its neutral position. This movement of the control lever causes l 3 the right hand piston of valve member Illa to close the port H for-locking the pressure fluid in the hoist cylinder II3.

When the bucket 5I and its arm 41 are to be returned to the desired digging position, the hoist control lever |45 is moved clockwise, as viewed in Fig. 15. This movement of the hoist control lever causes the right hand piston of valve member I42a to be moved to uncover port H. This port H then is placed in communication with port J by the valve chamber I 23h. The pressure fluid then will be exhausted from the hoist cylinder 3, by the weight of the bucket 5| and its arm I1, and the exhausted pressure fluid will flow from the pipe line |22 to the return pipe line 13.

When the bucket 5I and its arm 41 are to bel swung in one direction or the other, the swing control lever |50 is moved either counterclockwise or clockwise, as viewed in Fig. 15. If this lever |50 is moved counterclockwise, the right hand piston of valve member I41a will be moved to the right to uncover port F while the left hand piston of valve member I 41a will be moved to the right to uncover port E. Pressure uid then will iiow from pipe line |33 into the duct A and from this duct through the valve chamber I33b to the port F and through this port to the communicating pipe line |32 that leads to one end of the swing cylinder I3 I. The pipe line |32 that connects with the opposite end of the swing cylinder |3I is placed in communication with the valve chamber |33b through the port E. The duct K then functions to establish a ilow path from the port E, and the associated end portion of the valve chamber |331), to the left hand end of the valve chamber I23b. This end of valve chamber I23b is provided with port L which communicates with the return pipe line 19. Consequently, uid in the end of swing cylinder I3I that is'connected with the left hand pipe line |32 will be exhausted through the port E, the valve chamber |33b, the duct K, the valve chamber I23b, and the port L.

When the bucket 5I and its-arm l1 are to be swung in the opposite direction, the swing control lever |50 is moved clockwise, as viewed in Fig. 15. This movement of the control lever |50 'causes the two pistons of valve I41a to be moved to the left. This movement of the pistons of the valve member I41a causes port E to be uncovered so that pressure i'luid can flow from pipe line |38 through duct A into the valve chamber I 33h and through this chamber into port E for ow through the left hand pipe line I 32. The right hand pipe line |32 has been placed in communication with the return pipe line 19 by the uncovering of port F. This returning or exhausting fluid will flow from the port F through the right hand end portion of valve chamber Illb into the duct G and from this duct through the right hand end portion of valve chamber |2311 into port J.

Movements of the swing control lever |50 in these opposite directions will cause the pistons ofvalve member Illia to be moved successively into the position that will close the adjacent ends of ducts B and C. Consequently, the pressure fluid that is admitted to valve chamber I33b will not be permitted to flow to the port D that communicates with the return pipe line 19.

After the bucket 5I and its arm `41 have been hoisted to the desired elevation and swung to the proper dumping position, on either side of the tractor, the trip cylinders 13 for the latches 61 are energized to trip the bucket. These trip avan? cylinders are energized by actuating the contro lever I II for the trip control valve Il. This actuation of the control lever |5I closes the vave 33 and causes iluid pressure to be built up in the return line 1I, and from this return line in the tube 11, the Tcoupling 1l, and the branch tubes 15. After the latches 31 are tripped, the control valve I0 is opened again so that the springs 1I canr function to return the latches Il to their bucket engaging positions.

Where it is used in the claims, the expression standard tractor is to be understood and construed as referring to and covering any complete motor propelled wheel or crawler supported tractor unit that is obtainable on the open market; i. e., any general purpse standard product of recognized tractor manufacturers, and is not to be understood and construed as referring to and covering any motor-propelled wheel or crawler supported unit thatl is designed and constructed especially for use with and as a non-detachable or non-separable part of shovel mechanism.'

It is to be understood that the form of this invention herewith shown and described is to be taken as the preferred example of the same, and that various changes in the shape, size, and arrangement of parts may be resorted to without departing from the spirit of the invention or kthe scope of the subjoined claims. Y

Having thus described the invention, we claim:

1. In a front end tractor implement, the combination with a standard tractor having its power plant positioned at the front end thereof, of a complete shovel mechanism assembly detachably mounted as a self-contained attachment unit on said tractor, said shovel mechanism comprising a bucket, means for supporting the bucket for hoisting ,and lowering movements in front of the tractor, power plant and for lateral swinging movement in either direction when raised above thelevel of the tractor power plant, and a hydraulic system forefecting such movements of the bucket and including a pump, driven by the power plant of the tractor, for developing the iiuid pressure in the hydraulic system.

2. In a front end tractor implement, the combination with a standard tractor having'its power plant positioned at the front endthereof, of a complete shovel mechanism assembly mounted as a self-contained attachment unit on said tractor, said shovel mechanism comprising a base frame including side beams positioned on opposite sides of said tractor, tractor mounting means carried by the side beams of said base frame, a bucket, means mounted on the base frame and straddling the power plant of the tractor for supporting the bucket for hoisting and lowering movements when the bucket is positioned in front of the-tractor power plant and for lateral swinging movement in either direction relative to the tractor when the bucket is positioned at a higher level than the top of the power plant, and a hydraulic system for effecting such movements of the bucket and including a, pump, driven by the power plantof the tractor, for developing the fluid pressure in the hydraulic system.

3. In a front end tractor implement, the combination with a standard tractor, of a complete shovel mechanism assembly mounted as an attachment unit on said tractor, said shovel mechanism comprising a base frame, tractor mounting means carried by the base frame, a mast assembly mounted on and projecting above the base frame and including a vertical mast post rotatable relative to the remainder of the mast assembly, an arm pivoted to and entirely supported by the upper end portion of the mast post, a bucket pivotally mounted on the outer end of said arm. and a hydraulic system carried by the base frame and the rotatable mast post and including a motor for hoisting and lowering the bucket at the front end of the tractor by pivoting the arm, a motor for swinging the bucket in either direction relative to the tractor by rotating the mast post. and a pump, driven by the power plant ot the tractor, for developing the iluid pressure in the hydraulic system.

4. In a iront end tractor implement, the combination with a tractor having a power plant, and ground engaging traction means driven by said power plant, of a frame structure attached to the tractor, a mast assembly supported on the frame structure and including a rotatable mast post, an arm pivoted to the mast post for vertical movements, a bucket pivotally connected to the outer end o! the arm, means for holding the bucket in digging and load carrying position with respect to said arm and for releasing the bucket from said position so that it will pivot into its load dumping position, means carried by the mast post for eilfecting pivoting of the arm, and means mounting on the frame structure for eilecting rotation of the mast post.

5. In a front end tractor implement, the combination with a tractor having a powerV plant and ground engaging traction means driven by said power plant, of a frame structure attached to the tractor, a mast assembly supported on the frame structure and including a rotatable mast post, an arm pivoted to the mast post for vertical movements, a bucket pivotally connected to the outer end of the arm, means for holding the bucket in digging and load carrying position with respect to said arm and for releasing the bucket from said position so that it will pivot into its load dumping position, means for utilizing the downward pivotal movement of the arm for eiiecting pivotal movement of the bucket from its load dumping pition into its digging and load carrying position, and means carried by the frame structure for effecting rotation of the mast post and pivoting of the arm. y

6. In a front end tractor implement. the combination with a tractor having a power plant, and ground engaging traction means driven by said power plant, of a frame structure attached to the tractor, a mast assembly supported on the frame structure and including a rotatable mast post, an arm pivoted to the mast post for vertical movements, a bucket pivotally connected to the outer end of the arm, means for holding the bucket in digging and load carrying position with respect to said arm and for releasing the bucket from said position so that it will pivot into its load Vdumping position, means associated with the mast assembly and the bucket for utilizing the downward pivotal movement of the arm for effecting pivotal movement of the bucket from its load dumping position into its digging and load carrying position, means carried by the mast post for eiecting pivoting of the arm, and means mounted on the frame structure for effecting rotation of the mast post.

7. In a front end tractor implement, the combination with a tractor of the crawler or Wheeled type and having a power plant on its front end portion, of a bucket, means mounted on the tractor rearwardly of its power plant for supporting the bucket for hoisting and lowering movements at the front end of the tractor forwardly of its l16 power plant and for lateral swlnging'movements in either direction when elevated above the said power plant, and a hydraulic system carried by the tractor for effecting such movements of the bucket.

8. In a front end tractor implement, the combination with a standard tractor having' a power plant, and ground engaging traction means driven by said power plant, of a frame structure attached to the tractor, a mast assembly supported on the frame structure and including a rotatable mast post, an arm pivoted at its inner end and supported solely by the mast post for vertical movements, a bucket pivotally supported by the arm, and a hydraulic system for actuating the mast post and arm including a motor supported on the frame structure for rotating the mast post, and a motor supported on the mast post for pivoting the arm relative to the post.

9. In a front end tractor implement, the combination with a standard tractor having a power plant, and ground engaging traction means driven by said power plant, of a frame structure attached, to the tractor, a mast assembly supported on the frame structure and including a rotatable mast post, an arm pivoted to the mast post for vertical movements, a bucket pivotally connected to the outer end of the arm, means for holding the bucket in digging and load carrying position with respect to said arm and for releasing the bucket from said position so that it will pivot into its load dumping position, and a hydraulic system carried by the frame structure for effecting rotation of the mast post and pivoting of the arm.

10. In a front end tractor implement the combination with a standard tractor having a power plant, and ground engaging traction means driven by said power plant, of a frame structure attached to the tractor, a mast assembly supported on the frame structure and including a rotatable mast post, an arm pivoted to the mast post for vertica1 movements, a bucket pivotally connected to the outer end of the arm, means for holding the bucket in digging and load carrying position with respect to said arm and for releasing the bucket from said position so that it will pivot into its load dumping position, means associated with the mast assembly and the bucket for utilizing the downward pivotal movement of the arm for effecting pivotal movement of the bucket from its load dumping position into its digging and load carrying position, and a hydraulic system carried by the frame structure for effecting rotation of the mast post and pivoting of the arm.

11. In a front end tractor implement, the combination with a tractor having a power plant, and ground engaging traction means driven by said power plant, of a base frame including side beams arranged longitudinally of the tractor on opposite sides of said power plant and attached to the tractor under-carriage, a mast assembly supported on the base frame rearwardly of the power plant of the tractor, said mast assembly comprising an upstanding stationary mounting, a vertical mast post rotatably supported by and projecting above the mounting, and a head structure attached to the projecting end portion oi' the mast post to rotate therewith; a Abucket arm pivotally supported by said head structure to partake of vertical movements, a bucket pivotally attached to the outer end of said arm, means carried by the mast post head structure for eiecting pivotal movements ofthe bucket arm,

17 and means mounted on the base frame for effecting rotation of the mast postfrelative to its stationary mounting.

12. In a front end tractor implement, the combination with a tractor having a power plant, and ground engaging traction means driven by saidl power plant, of a base frame arranged longitudinally of the tractor and attached to its under-carriage, a mast assembly supported on the base frame rearwardly of the power plant of the tractor, said mast assembly comprising av mounting, a vertical mast post rotatably supported by the mounting, and ahead structure attached to the upper end portion 'of the mast post to rotate therewith; a bucket Aarm pivotally supported by said head structure to partake ofvertical movements, a bucket, a loose pivotal connection between the bucket and the outer end of said arm to permit the bucket to move between a digging and load carrying position and a dumping position and to permit the bucket to be displaced relative to the end of the arm as a result of thrust developed during;A digging action, a pair of thrust platesattached to the front end portion of the base -frame and engaged by the bucket when displaced to apply the digging thrust directly to the base frame, means carried by the Vmast post head structure forV effecting pivotal movements of the bucket arm, and means mounted on the base frame for effecting rotation of the mast post.

13. In a front end tractor implement, the combination with a tractor having a power plant, and ground engaging traction means driven by said power plant, of a frame structure attached to the tractor, a mast assembly supported on the frame structure and including a rotatable mast post, an arm pivoted to the mast post for vertical movements, a bucket, a loose pivotal connection between the bucket and the outer end of said arm to permit the bucket to move between a digging and load carrying position and a dumping position and to permit the bucket to be displaced relative to the end of the arm as a result of thrust developed during digging action, a pair of thrust plates attached to the front end portion of te base structure and engaged by the bucket when displaced to apply the digging thrust directly to the base structure, and means for effecting rotation of the mast post and pivoting of the arm.

14. In a front endl tractor implement, the combination with a tractor having a power plant, and ground engaging traction means driven by said power plant, of a frame structure attached to the tractor, a mast assembly supported on the frame structure and including a rotatable mast post, an arm pivoted to the mast post for vertical movements, a bucket, a loose pivotal connection between the bucket and the outer end of said arm to permit the bucket to move between a digging and load carrying position and a dumping position and to permit the bucket to be displaced relative to the end of the arm as a result of thrust developed during digging action, a pair of thrust plates attached to the front end portion of the base structure and engaged by the bucket when displaced to apply the digging thrust directly to the base structure, means 'carried by the mast post for effecting pivoting of the arm, and means mounted on the base frame for eiecting rotation of the mast post.

15. In a front end tractor implement, the combination with a tractor having a power plant,

and ground engaging traction means driven by 18 said power plant, of a base frame arranged longitudinally of the tractor and attached to its undercarriage, a mast assembly supported on the base frame rearwardly of the power plant of the tractor, said mast assembly comprising a mounting, a vertical mast post rotatably supported by the mounting, and a head structure attached to the upper end portion of the mast post to rotate therewith and including a pair of parallel, horizontally extending bracket arms, and a pair of horizontally aligned stub shafts arranged at right angles to the bracket arms; a bucket arm pivotally sup- Aported by said stub shafts, a bucket attached to the outer end of said arm, means mounted on the bracket arms for etlecting pivotal movement of the bucket arm, and means mounted on the base frame for effecting rotation of the mast post.

16. In a front end tractor implement, the combination with a tractor having a power plant, and ground engaging traction means driven by said power plant, of a base frame arranged longitudinally of the tractor and attached to its undercarriage, a mast assembly supported on the base frame rearwardly of the power plant of the tractor, said mast assembly comprising a mounting, a vertical mast post rotatably supported by the mounting, and a head structure attached to the upper end portion of the mast post to rotate therewith and including a pair of parallel, horizontally extending bracket arms, and a pair of horizontally aligned stub shafts arranged at right angles to the bracket arms; a bucket arm pivotally supported by said stub shafts, a bucket attached to the outer end of said bucket arm. and a hydraulic system for actuating the mast post andbucket arm including a motor supported by the base frame for rotating the mast post, and a motor supported by the bracket arms for effecting pivotal movement of the bucket arm.

17. In a front end tractor implement, the combination with a tractor having Aa power plant and ground engaging traction means driven bythe power plant, of a frame structure attached to the tractor, a mast assembly supported on the frame structure and including a rotatable mast post, an arm pivoted to the mast post for vertical movements, a bucket pivotably connected to the outer end of the arm, means for holding the bucket in digging and load carrying position with respect to said arm and for releasing the bucket from said position so that it will pivot downwardly into its load dumping position under its own Weight,

means for controlling the rate of downward pivotal movement of the bucket during dumping to control the rate of spillage of material from the bucket, and means carried by the frame structure for effecting rotationof the mast post and pivoting of the arm.

18. In a front end tractor implement, the combination with a tractor, of a mast assembly supported on the tractor and including a rotatable mast post, an arm pivoted to the mast post for vertical movements relative to said post and for horizontal swinging movements with the post when the later is rotated, a bucket pivotally connected to the outer end of the arm, means for holding the bucket in digging and load carrying position With respect to said arm and for releasing the bucket from said position so that it will pivot-downwardly into its load dumping position under its own weight, means carried by the rotatable mast post and operatively connected to the bucket for controlling the rate of downward pivotal movement of the bucket during dumping to control the rate of spillage of material from the bucket and also operable to utilize the downward pivotal movement of the arm for effecting pivotal movement of the bucket relative to the arm from its load dumping position into its digging and load carrying position, and a hydraulic system carried by the tractor for enecting rotation of the mast post Vand vertical movement of the firm.

19. In a front end tractor implen ent, the combination with a tractor having a power plant, of a mast assembly mounted on the tractor and including a rotatable mast post, an arm pivoted to the mast post; a hydraulic system for actuating the mast post and arm including a fluid motor for rotating the mast post. a fluid motor for pivoting the arm, a pump driven by the power plant of the tractor, piping through which fluid is continuously circulated under pressure by the pump, and valve means for selectively applying the uid under pressure to the aforesaid fluid motors: a bucket pivoted to said arm, a springloaded latch for releasably holding the bucket in its digging and load carrying position with respect to the arm, an expansible cylinder oonnectedto the said latch and adapted to be expanded by iluid pressure to trip the latch for releasing the bucket so that the latter will pivot into its load dumping position, a pipe line connecting the expansible cylinder to the piping of the hydraulic system at a point where the fluid is returning for recirculation by the pump, and a valve in said system piping down-stream of the point of connection of the said expansibl'e cylinder pipe line thereto and operable to cause nuid pressure for expanding said cylinder to be built up in the pipe line leading to said cylinder.

20. In a front end tractor implement. a base frame, a bucket arm, means for supporting the bucket arm on the base frame forvertical pivotal movements, a bucket, a loose pivotal connection between the bucket and the outer end portion of said arm to permit the bucket to move between a digging and load carrying position and a dumping position and to permit the bucket to be displaced relatfve to the end of the arm as a result of thrust developed during digging action, and a pair of thrust plates attached to the front end portion of the base frame and engaged by the bucket when displaced to apply the digging thrust directly to the base frame.

21. In a tractor implement, a mast assembly comprising a mounting, a vertical m'ast post rotatably supported by the mounting, and a head structure attached to the upper end portion of the mast post to rotate therewith and including a pair of parallel bracket arms, and a pair of aligned stub shafts aranged at right angles to the bracket arms; a work arm pivotally supported by said stub shafts, load carrying means associated with the outer end of the work arm, and means mounted on the bracket arms for effecting pivotal movement of the work arm.

22. In a tractor implement, a mast assembly comprising a mounting, a vertical mast post rtatably supported by the mounting, and a head structure attached to the upper end portion of the mast post to rotate therewith and including a pair of parallel bracket arms, and a pair of aligned stub shafts arranged at right angles to the bracket arms; a work arm pivotally supported by said stub shafts, said work arm comprising an arched branch that straddles the head structure of the mast post and a pair of branches extending at right angles to the arched branch; load carrying means associated with the outer ends of the pair of branches of said work arm; a hydraulic motor including a cylinder pivotally supported by the bracket arms and a piston in the cylinder having its rod projecting from the latter; and means for operatively connecting the piston rod to the arched branch of -said work arm' for causing movements of the piston in the cylinder to effect pivotal movements of the work arm.

23. In a tractor implement, a mast assembly comprising a mounting, a vertical mast post r0- tabably supported by the mounting, a head structure 'attached to the upper end portion of the mast post to rotate therewith and including a pair of parallel bracket arms, and a pair of aligned stub shafts arranged at right angles to the bracket arms; a work arm pivotally supported by said stub shafts, said work arm oomprising an arched branch that straddles the head structure of the mast post, and a pair of branches extending at right angles to said arched branch; load carrying means associated with the outer end of the work arm, and means mounted on the bracket arm for effecting pivotal movement of the work arm.

24. In a tractor implement, a mast assembly comprising a mounting, a vertical mast post rotatably supported by the mounting, a head structure attached to the upper end portion of the mast post to rotate therewith and including a pair of parallel branch arms, and a pair of aligned stub shafts arranged at right angles to the bracket arms: a work arm pivotally sup-l ported by said stub shafts, load carrying means associated with the outer end of the work arm: a hydraulic motor including a cylinder pivotally supported by the bracket arms and a piston in the cylinder having its rod projecting from the latter; and means for operatively connecting the piston rod to the said work arm for causing 4movements of the piston in the cylinder to effect pivotal movements of the work arm. TROY M. DEAL. WALTER BAKER. HENRY S. DUTTWEILER..

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 105,883 Bailey Aug. 2, 1870 1,328,487 Billings Jan. 20, 1920 1,422,767 Keast July 12, 1922 1,874,831 Talboys Aug. 30, 1932 1,937,016 Gibby Nov. 28, 1933 1,975,359 Garson Oct. 2, 1934 1,987,982 Wheeler Jan. 15, 1935 2,019,938 Stephens Nov. 5, 1935 2,075,819 Manly April 8, 1937 2,190,346 Austin Feb. 13, 1940 2,242,511 Cook May 20, 1941 2,260,539 Ruddock Oct. 28, 1941 2,304,443 Butler Dec. 8, 1942 2,387,764 Maxwell Oct. 30, 1945 2,391,857 Arps et al. Jan. 1, 1946 2,412,412 Melli Dec. 10, 1946 2,413,095 Barker Dec. 24, 1946 2,413,096 Barker Dec. 24, 1948 2,413,097 Barker Dec. 24, 1948 2,416,893 Barker Mar. 4, 1947

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