US2443537A

US2443537A - Variable pitch power shovel

Info

Publication number: US2443537A
Application number: US625274A
Authority: US
Inventors: Walter A Hilgeman
Original assignee: Individual
Current assignee: Individual
Priority date: 1945-10-29
Filing date: 1945-10-29
Publication date: 1948-06-15
Anticipated expiration: 1965-06-15

Description

June 15, 1948. w. A. HILGEMAN 2,443,537

VARIABLE PITCH Pom SKOVBL Filed Oct. 29, 1945 4 Sheets-Sheet 1 INVENTOR. MLTER Alf/L GEM/1N MW &

Arrozams vs June 15, 1948. w. A; HILGEMAN VARIABLE PITCH POWER SHOVEL 4 Sheets-Sheet 2 Filed Oct. 29, 1945 mmvron. WALTEE A. Huce MAN BY$M1MM a M June 15, 1948. w. A. HILGEMAN 2,443,537

VARIABLE PITCH POWER SHOVEL Filed Oct. 29, 1945 4 Sheets-Sheet 5 INVENTOR.

WALTER A. H/L GEM/UV BYW & W

June 15,- 1948.

Filed Oct. 29, 1945 W. A. HILG EMAN VARIABLE PITCH POWER SHOVEL 4 Sheets-Sheet 4 INVENTOR. Mme-,2 A. H/z. GEM/1N BYflMAdZ/Ct & 54mm Patented June 15, 1948 UNITED STATES PATENT OFFICE 9 Claims.

This application relates to improvements in the power driven shovels and the operation thereof. More particularly, it relates to an apparatus for varying the tilt of a dipper on a mobile power driven shovel so as to make the operation of the dipper more flexible in digging and picking up a load and for tilting the loaded dipper so that it is emptied cleanly when dumped.

The operation of power driven shovels having a dipper on a dipper handle is extensive for mining of coal, ores, etc, where the job requires a combination of digging and moving of materials. Shovels of this type are loaded by a forward thrust of the dipper. The loaded dipper is raised until the back of the dipper is at the bottom and is emptied by opening a door in the back of the dipper. The tilt of the dipper depends largely upon the height to which it is raised before it is dumped. It is impractical to raise the dipper through sufficient of an are so that all of the contents fall from the dipper when it is dumped even if such machines could be designed. As a consequence, a large amount of material remains on the inclined dipper floor, for example, as much as 150 pounds or more of coal will remain in a dipper designed for about seven cu. yd. capacity. Since clippers up to 35 cu. yd. capacity are built and the material retained is more or less in proportion, the loss of efiiciency is apparent.

There are two general types of power shovels in which the dipper isfilled by a forward thrust or crowding action. In general, they comprise a crane or boom which may be varied in its angle of tilt relative to the horizon. A sheave is 'located at the top or forward end of the boom. A cable or hoisting rope passes from a power driven winch contained in the cab of the shovel, over the sheave and is attached by a blockand tackle arrangement to the bail of a dipper. The dipper is attached to a handle arranged to be thrust forward or withdrawn relative to the .machine. The dipper is open at the front with horizontal digging teeth and has a solid bottom, top, and sides with a hinged door in the rear which can be opened by the release of a latch and through which the contents of the shovel are dumped when it is held in an elevated position. Attached to the front of the dipper is a conventionalbail for elevating the dipper. operated by one of several mechanisms. In one type known as the gear and rack type, the handle which in this case is referred to as the dipper stick, may be split so that it passes on either side of the boom through an appropriate gearand The dipper handleds bearing mechanism located midway of the boom. By means .of .a crowd mechanism the dipper stick may be moved back and forth through this mechanism in such a, way that the dipper is brought closer to or thrust farther from the boom. By manipulating the crowd and at the same time lowering or raising the dipper, it can be filled or maneuvered into position for dumping. The crowd mechanism serves as a pivotal point for the dipper handle so that the dipper may be moved in a vertical arc, the radius of which depends on how far forward or back the dipper handle is moved with relation to theboom. In the operation, the dipper handle is usually retracted and lowered so as toibring the dipper into the digging position. The dipper is loaded by crowding the dipperhandle away from the boom and at the same time elevating the dipper by the block and tackle arrangement previously described. When the dipper is to be dumped, the dipper handle is thrust far forward and the dipper elevated still further and moved into the dumping position and the latch holding the door is released. This invention is applied to the gear and rack type shovel by adding another stick or tilting stick parallel to the dipper stick and also provided with a rack. This rack engages with a gear of smaller diameter thanthe gear operating the main dipper stick so that the tilting stick moves less than the main dipper stick. Attached to the end of the tilting stick and to the front of the dipper is a link which acts on the front of the dipper tomove it upward or downward. The dipper stick itself is pivoted to the top of the dipper near the rear.

Another common type of shovel arrangement is the so-called knee action type such as is illustrated in the accompanying drawings. The boom is in the form of a-hollow A. A secondary boom is pivotally attached to the frame of the machine and this also may be an A shape. At the top of the secondary boom is the point of pivotal attachment of the dipper handle. Thus if the dipper is raised or lowered it describesan are centered at the top of the secondary boom. The crowd mechanism comprises a stick which is pivotally attached to the top of the secondary boom and which passes through asuperstructure located on the top of the cab. This crowd .is slidably mounted in bearings and is so arranged that it can be driven forward or backward for a limited distance, thereby changing the slope of the secondary boom and at the same time crowding the dipper handle forward or backward. As the dipper is raised it passes through an arc, the radius of which is the length of the dipper handle, but the position of which relative to the boom will depend upon how far forward or back the stick is thrust. The mode of attaching the bucket to the dipper handle and of raising and lowering the bucket is otherwise similar to the gear and rack type.

Both of these types of mechanism have certain limitations. Principally, the angle of tilt of the bucket with relation to the horizon is a direct function of the distance of the dipper from the point at which it pivots. In the first described type of shovel the length of the dipper handle can be varied because the crowd mechanism and the dipper handle are the same. In the knee action type of apparatus, the arc is fixed because the length of the dipper handle is fixed, Both types of machines have certain uses to which they are best adapted, but in both instances the dipper cannot be raised to the point at which the bottom is in a vertical position and will empty itself completely. If it were possible to do this, the speed of the operation is materially decreased because of the greater height to which it must be raised. My invention may be applied to either type of apparatus. It provides a means by which the forward part of the dipper travels at a more rapid rate of speed than the rear part during the time that it is being raised or lowered. This is done by providing a link pivotally attached to the front of the dipper and having a dipper handle pivotally attached to the rear of the dipper, the link and the dipper handle operating around centers spaced from one another.

It is an object of my invention to provide a means for overcoming these difficulties and to increase the speed and efficiency of operation as well as to improve power shovels of this type to minimize breakage.

In one specific embodiment, this invention comprises an improvement in a power driven shovel in which the dipper is filled by a forward stroke and emptied through a door in the rear, said dipper being pivotally attached to a dipper handle for elevation and also to a link forward of the point of attachment of the handle, said handle being pivotally mounted on said shovel remote from the point of attachment to the dipper, said link being pivotall associated with the power shovel adjacent to but spaced from the center about which the dipper handle pivots when the dipper is raised and lowered, the associating being in such a manner that the dipper handle and the link pivot around different centers, whereby the pitch of the bottom of the dipper is varied as it moves through an arc to an extent greater than would occur were the dipper rigidly attached to the dipper handle.

Figure 1 illustrates diagrammatically the device as attached to a power driven shovel, the dipper being in position for loading. Figure 2 shows the device when the dipper is raised into position to be dumped. Figure 3 illustrates a modification of the link attachment. Figure 4 is a front view of the dipper, link, dipper handle, and the point of attachment to the stick and secondary boom of the shovel. The dipper bail has been omitted. Figure 5 is a detail in perspective, partly in section, showing one arrangement of the top part of the dipper handle at its point of association with the stick and the secondary boom. Figure 6 is a top view partly in section of a guide means for guiding and steadying the link at its upper end. Figure 7 is a detall in perspective of the top of the link showing one mode of attaching it to the stick. Figure 8 is a detail in perspective showing the manner of operating the crowd on the stick. Figure 9 is a detail showing the connection of the dipper handle with the dipper. Figure 10 is a detail in perspective showing another variation of the mode of attaching the dipper handle to the dipper. Figure 11 is a side view and Figure 12 an end view in perspective of a device for attaching the link to the dipper as illustrated in Figure 3. Figure 13 is a detail partly in section showing an apparatus for connecting the link with the dipper so as to permit a partial pivoting of the dipper in a lateral direction. Figure 14 is a detail of the traveler to which the link is attached and which rides in the track shown in Figure 13. Figure 15 is a detail of the link connection shown in Figure 3.

Referring to Figure 1 the tractor and cab of the device are diagrammatically illustrated at 20. Extending above this is a framework 2| which is shown in very little detail for sake of simplifying the drawings. This comprises an A frame 2| which supports the stick 22 and a sheave 23 together with gearing mechanism, etc, for operating the shovel. This is a conventional arrangement well understood by those skilled in this art and need not be described in detail since it varies with different makes and sizes of shovels and forms no part of the invention. The stick 22 has a stop 23' at the end and a second stop 24 to limit the motion forward and back. This stick may be supported as illustrated in Figure 8 in

slide bearings

25 and 26 which are supported on a shaft 21 that is journaled in a bearing support 28 attached to A frame 2|. A gear 29 driven by conventional means not shown is used to turn a drum 30 which is rigidly attached to the shaft 21 at a point between slid

bearings

25 and 26. A cable 3| passes one or more times around drum 38. This cable is attached at one end of the stick 22, for example b means of eye bolt 32, and is attached to the other end of the stick at a point not shown near the forward end thereof. As the stick is moved forward or back the cable 3| winds and unwinds around drum 39. The cable is kept taut by any conventional means. The stop 23 should be wider than end 33 of the stick in order to leave a space to accommodate the eye bolt 32 and cable fastening and also to permit the main hoist cable 34 to pass over the sheave 23 and down between

members

35 and 35 of stick 22 into a hoist drum within the body of the shovel 20. This cable 34 passes to the left of cable 3| and behind drum 3!]. This leaves plenty of clearance for the operation.

The stick 22 is made up of two side pieces 35 and 36 slidably mounted in

bearings

25 and 25 respectively. This stick structure may be solid as indicated by members 35 and 36 or may be in the form of a box made by joining material to form a rectangle, as shown in Figure 10, member 55. It may be of conventional structure otherwise. The invention is not limited to this kind of stick or of effecting the crowd. Any conventional type of crowd and stick may be used. The forward end of stick 22 has a cross piece which may have a recess into which

castings

31 and 38 fit flush with the stick. These may be held in place by bolts, screws, or dowels 39.

Castings

31 and 38 are arranged to be replaceable if they should break or wear out.

The forward end of the stick is pivotally supported on secondary boom 40 by means of a shaft M which passes through a universal joint 42 which in turn supports dipper handle M at. The pivotal movement of the forward: end of the stick in relationship to the boom is such as to form a segment of an are having a center at point 45 at which boom 4b is pivotally attached to the main body of the shovel. When the stick is crowded forward or back, the forward end describes an arc in the direction which theshovel is facing. The radius oi the arc is equal to the length of secondary boom M, and the maximum length of the arc is equal to the length of the thrust stroke of stick 22.

The cable 34 passes around sheave 46 which is mounted at the forward end of boom 4'1. The cable then passes around sheave 118 on which is mounted a bail 4&9 attached to dipper 50 by means of lugs or brackets 5|. The arrangement of primary boom H and the block and tackle attachment as well as the bail and dipper attachment are conventional. For example, this is used in the coal loading shovels, earth movers, etc., of the knee action type.

The dipper 50 comprises a conventional door 52 which may be equipped with a conventional latch, not shown.

The dipper handle '43 comprises a yoke 53 which is attached with a dowel 44 to the universal joint 42 in the end of stick 22. The yoke has a neck which is solid except for a tapered passage 54 shown by the dotted lines in Figure l and Figure 4 for the link 56 to pass through. The main section of the stick is indicated at :55 and is designed to permit the passage of link 56 and is preferably of split construction. The dipper handle may be pivotally attached to the top of the dipper adjacent the rear part near the door hinge. One preferred mode of attachment is shown in Figure 9. The top of the dipper comprises a casting 51 which serves as a bearing for shaft 58 and also as a spacer and guide for yoke 59 which is detachably mounted to the dipper handle 43 by means of'bolt 60 and nutfil. The yoke 59 passes on either side of casting 511 and between two cars 62 and 63 which mayalso be cast or otherwise mounted integral with dipper 50. The shaft 58 is journaled in the cars 62 and 63 and in guide means 51 thereby permitting vertical pivoting of the dipper in a direction parallel to the direction in which the shovel is facing.

The dipper door is pivotally mounted at-M in the ears and 53, this being conventional. The yoke 59 being detachably mounted in the dipper handle, has the advantage that it can be replaced in the event it should become damaged or in the event the dipper handle should be broken. It will be noted from the various illustrations, particularly Figure 9, that two sides of the dipper handle 55 and 55' are joined by a solid piece 55 which is relieved slightly on the forward side in order to permit clearance of the link 56 at all times. The bolt '60 passing through piece 65 permits a slight pivoting around the end of the dipper handle of yoke 59. The reason for this will be apparent in connection with the description of the link attachment which provides for a comparatively small amount of lateral pivoting of the dipper.

A variation of the arrangement is shown in Figure 10. This is partly in section and shows one possible structure of the dipper handle in which the sides 55 and 55' may be hollow, in the form of rectangles. In this variation no yoke is used. Instead, a casting 66 is used which is an extension of the dipper handle and which is relieved at 61in order to pass over the shaft 6'4 on which the 6. dipper door is pivotally lnmg. On. either $112 attire-casting cam. spacers and. Theshatt 53 passes through. these spacers and maths: 56.. When mounting this. on a dipper, the casting 51 is eliminated and thespaoers. and casting $5 occupy the space between cars 62 and 63. The embodiment shown in Figure 9. is preferred.

The preferred mode of attachment of link 56 will now be described. Refierring to Figure l, the ears 3! and 38 attached tostick extend i'orward of'the stick in the manner illustrated. They are detachably mounted by pins. 39 so that they may be replaced if broken or ifthey become worn. A track 10 is cast into the ears. This serves to guide the end of the link 58 in a manner haremafter described while serving :as a track :ior rollers H and 12. It will be noted thattheears curve in a forwardly and downward direction then break downwardly at a steeper angle, curve backward and upward and finally flatten out in'a plane more or less parallel with the stick. The latter part of the track should be long enough so that the rollers H and I2 not strike the back of the track. This is to prevent damage to stick 22, the rollers or to link 56. The upper and forward end of the track is likswiseextended sufficiently far upward so that the rollers will never strike the end of the track thereby 'preventing damage from this cause when the dinner is raised to its highestpoint. The-shane'of the track is designed so as to assist in giving the dipper 50 a sharper angle of. tilt when in the digging position, that is, at the point where it is lowered to its furthest point and directed forward and downward'into the ground. It also assistsin keeping the dipper level with the ground afteritleaves a'certain point in its forward motion, this being assisted by the proper manipulation of stick 22. When the dipper'bcgins its upward motiornthe track causes a more rapidraisingof the forward end of the dipper than the rear end so that it will be practically vertical at the dumping position. This can be attained without raising the dipper any farther than is now done with conventional clippers. In the latter case. however, the bottom of the dipper is far from vertical.

The preferred form of thelink attachment consists of a mainshaitifi which passes to a cross arm :13 having rollers H and l2smounted thereon. The link 56 passes to cross arm 73 and is mounted by a ball and socket joint at'point 'M. A

bolt 15 passes through cross arm 13. The bolt is held in position by means of nut '16, spring 11, and washer l8. Extending at right angles and slightly upward of cross arm 13 are guide arms 18 and having guide projections 8i onthe ends thereof. These operate in' vertical tracks 83 which may be cast in the inside surfaces of yoke 53. Any suitable conventional track mounting rmay be used. Instead of being slideably mounted in the track as illustratedythe use of ballbearings, needle bearings, and the like to reduce friction is also contemplated. Thus when-the link slides vertically in dipper handle 55. the cross arm 13 is guided and maintained in the proper relationship so as to prevent its twisting in the track 10. When the dipper handle is swung through its arc and when the forward end of the dipper is lifted so that the dipper pivots around point 58, the link 56 tends to slide upward along the tapered slot 54. If no guide means such as BI and arm 18 were provided, there might be a tendency for the cross arm 13 to swing laterally with relationto the yoke so that the rollerswould'bindin the track and might be'broken or otherwise damaged. However, with an arrangement such as that shown the movement of the link is longitudinal with reference to stick 22, and it cannot twist so that the rollers are always in their proper operative position with the track 10.

Mounted on the top of dipper 50 by any suitable means including bolts, welds, etc., is a casting 84 comprising a body 82 and a track 85. This casting 84 serves as the forward pivot point of link 58 and dipper 50. One variation of this is shown in Figure 13. The second variation which will be described later is shown in Figures 3, l1, and 12.

Refer now to Figures 13 and 14, The track may be cast into the body 82 of casting 84 having a shape as indicated. This may consist of two tapered tracks or

races

86 and 81 to receive tapered

rollers

92 and 93. In addition to the races there is a groove in the body of track 85 extending below the point at which the races enter the body of the track and extending through the top of casting 84 to permit the traveler 88 to slide back and forth. This groove is approximately of the same width as the body part 88 of the traveler 89. The opening through the top of the casting permits the ears 90 of the traveler to extend therethrough. The traveler 88 consists of a body 89 having ears 90 extending from the top thereof, these ears being drilled to receive a shaft and being in the form of a yoke so as to receive the roller and link 55 in the manner illustrated in Figure 4. These ears permit pivotal attachment of the link 56 to dipper 50.

On retaining shafts 9| are

rollers

92 and 93 in a position to roll in tapered tracks or races 85 and 81 respectively of main track 85. Thus it will be seen that the traveler 88 can be caused to move in a semicircular are along the track in casting 84. This permits the dipper to turn somewhat in a lateral direction if one corner of the dipper should strike a rock or ledge during the loading operation, instead of snapping the dipper handle. The bucket would pivot in a lateral direction thereby relieving the tension somewhat and the lifting operation could be stopped by the operator, or the corner of the dipper would in some cases free itself without damaging the shovel. Attached to one end of the casting may be a plate 94 which retains the traveler 88 in the track but which can be removed so that the traveler 88 can be removed from the track 85 for repairs or replacement.

The manner in which this invention operates may be described as follows: At the time the dipper is to be filled, it has been lowered by releasing the block and tackle so that it is in the position shown in Figure 1. Stick 22 has been retracted to a greater or lesser extent depending upon the angle at which it is desired to have the bucket operate. As the stick is retracted (toward the left in the illustration) as far as it will go against stop 24, the dipper 50 will be somewhat lower than it is in the illustration and have a smaller tilt from the horizontal. Thus it becomes possible to change the tilt of the dipper as desired at the point so that it will dig downward, or clean up level with the ground. In a conventional dipper not having link 55, the angle to which the dipper can be tilted is decidedly limited.

Likewise when the conventionally mounted dipper is raised to the furthest extent for dumping there is a limit to the angle at which the dipper will tilt, because its position depends entirely upon the are through which it can be raised. If the arc in the conventional dipper is sufficiently great so that the dipper can be tipped until the bottom of it is vertical the boom must be raised to a point where it limits the forward thrust, thereby imposing additional limitation on the shovel operation. It is possible to increase the length of the stick and of the boom to accomplish this in part but as a general rule, this is impractical. Moreover it increases the general weight of the shovel which means a tremendous increase in cost. By means of my invention, the operation of the shovel becomes more flexible with very little, if any, increase in the cost of the shovel. Thus a great saving can be effected with a more satisfactory operation.

Referring again to Figure I particularly, the dipper is shown in position for loading and in Figure 2, in position for dumping. In the loading position in Figure l, the upper end of link 58 and the cross arm I3 with the roller II have passed down and around the point of track 10 and the secondary boom is in partially retracted position. The back end of the dipper pivots around point 58 as it swings through an arc which is centered on stick 22 at point M. The front end of the dipper pivots around the shaft passing through ears 98 and link 55 and swings through an arc the center of which is dependent on the position of cross arm 13 in the track 10. Thus it will be seen that the center of the are described by the nose of the dipper due to the efiect of link 56 is always substantially below the center point of the arc described by the dipper handle 43. The center of the are described is also forward of or rearward of or directly below point 4| depending on the position of the stick and the dipper handle. Thus as the dipper is raised, even though stick 22 were not moved in either direction, the front end of the dipper would always travel faster than the rear end. Therefore, the tilt of the dipper with relation to the horizon would vary throughout the arc. This means that as the dipper is moved downward and backward toward the main body of the shovel 20, the back end travels slower than the front end and the front end is crowded downward so that it is tilted at an angle and will be in a position to dig into the ground. As the dipper is raised, the front travels more rapidly and can be brought into a vertical position more quickly and at a point lower (in relation to the distance above the ground) than can be reached by the conventional machine. In order for these effects to be obtained the dipper must be pivotally attached to both the dipper handle and the pitch link 58. When at the upper limit of the dipper travel, the door 54 is opened and all of the material contained in the dipper drops out. In the normal operation in coal and earth moving machines, the dipper is dumped while still inclined and large amounts of material are held upon the bottom and teeth of the dipper. In a normal eight-hour day operation, approximately three carloads more of coal may be loaded when using my invention than when using the conventional equipment due to the fact that with my invention the dipper cleans itself entirely each time it is dumped. This means a saving, at the present rates, of the order of $150.00 per day.

Furthermore the greater angle of tilt of the dipper permits a speedier action so that in addition to the improved cleaning of the dipper, a larger number of operations can be completed in the course of a day, since the dipper is brought into loading and dumping positions more rapidly.

The operation of the stick is conventional in that it is crowded forward when digging and also pushed forward usually to its extremity when the bucket is raised for dumping. This permits the machine to be operated at a substantially increased distance from the car into which the material is being loaded than could be done by the old type because the heel of the dipper is several feet farther from the machine.

A modification of this device is shown in Figure 3. The stick 56 is turned slightly downward at the end and passes through a traveler 95 which is mounted for lateral arcuate movement in a casting 96 which is attached to the top of the dipper which may otherwise be as previously described. The link 56 passes through the channel in stick 43 and is pivotally mounted at a fixed point in secondary boom 40 on a shaft 91 which passes through the A shaped boom. The stick may be centered by any suitable method. The shaft 91 passes through eye 98 (see Figure 15) in the end of the link 56. It will be noted that the pivot point in this device is fixed instead of traveling as in the case of the preferred embodiment previously described. It is possible in this way to obtain an even more rapid action and a greater variability in the tilt of the dipper when conducting digging operations. This is desirable because the dipper can be tilted downward to a greater angle and reach the vertical dumping position more quickly. In this way the operation of the bucket is further speeded up.

The casting 96 contains a semicircular track 99 in which the traveler 95 is mounted. The traveler has a retainer 10!] on one side of the casting 96. Ears similar to ears 9G in traveler 88 for attachment to the lower end of stick 56 are provided with hole llll to receive a pin coupling the link and the traveler S5. The retainer I may be removed by a removing nut Hi2 from bolt I03. In this manner the safety feature is in corporated to prevent damage to the machine when the dipper strikes an obstruction that cannot be moved. The link can, of course, be used without this safety feature by providing a fixed pivotal attachment means to the dipper.

In an alternative form the tilting link or bar may be divided so as to pass on both sides of the dipper handle which may be solid. In this case the side pieces of the link are joined at each end and are attached to the connecting member. These are similar to those illustrated and are provided to attach the link to the pivotal point on the dipper and at the stick-secondary boom assembly in the manner taught herein. The connecting members may be screwed or bolted on to the end pieces of the link so that they may be removed readily if desired. If necessary the dipper handle may be relieved slightly along the angle formed by the link to cut down on the amount of space occupied by the assembly. While the link adds weight, this can be compensated for to some extent by making the dipper handle of lighter weight construction. The tilting link takes part of the load formerly carried by the dipper handle.

Having described the invention. it should be understood that it is not to be unduly limited by the exact embodiments illustrated or described.

I claim as my invention:

1. In a power shovel comprising a dipper filled by a forward stroke and emptied through a door in the rear, said dipper being attached to a dipper handle for elevation, said dipper handle being pivotally mounted on the shovel remote from the point of attachment to said dipper, and a boom for elevating the dipper, the improvement which comprises means for pivotally attaching the dipper handle on the top of and adjacent the rear of the dipper, a link pivotally attached to a point adjacent the front of the dipper, said link having a second pivot point at the opposite end located adjacent to but spaced from the end of the dipper handle remote from the dipper.

2. In a power shovel comprising a dipper filled by a forward stroke and emptied through a door in the rear, said dipper being attached to a dipper handle for elevation, said dipper handle being pivotally mounted remote from the point of attachment to said dipper and a. boom for elevating the dipper, the improvement which comprises for pivotally attaching the dipper handle on the top of and adjacent the rear of the dipper, a link pivotally attached to a point adjacent the front of the dipper, said link having a second pivot point at the opposite end located adjacent to but spaced from the end of the dipper handle remote from the dipper, said link and said dipper handle crossing one another between the pivot points.

3. In a power shovel of the knee-action type, comprising a. dipper filled by a forward stroke and emptied through a door in the rear, said dipper being attached to a dipper handle, said dipper handle being pivotally mounted remote from the point of attachment to said dipper on a secondary boom and thrust stick by which it may be thrust forward or retracted, and a boom for elevating the dipper, the improvement which comprises means for pivotally attaching the dip per handle on the top of and adjacent the rear of the dipper, a tilting link pivotally attached at a point adjacent the front of the dipper, said link having a. second pivot point at the opposite end located adjacent to but spaced from the pivotal mounting of the dipper handle on said secondary boom and stick, said link and said dipper handle crossing one another between the pivot points.

4. In a power shovel, the improvement comprising means for moving the forward end of a dipper upward at a higher rate of speed than the back end when the dipper is being elevated, said improvement comprising means for pivotally attaching a dipper handle on the top of the dipper and toward the rear thereof, means for attaching a tilting link on the top and near the front of the dipper, said link and said dipper handle being pivotally associated at the ends remote from the dipper with a stick and a secondary boom, the link passing diagonally through portion of the length of the dipper handle to a link-pivot means, said link-pivot means comprising a track adjacent the end of the stick and forming a part thereof and lying generally intermediate the ends of the dipper handle, lateral member on the upper end of said link comprising rollers riding in said track, and guide means associated with the stick to maintain the lateral member in proper operating relationship with said track.

5. In a power shovel of the knee action type, the improvement which comprises means for pivotally attaching a dipper handle to the dipper, means for pivotally associating a. tilting link with the dipper, means for pivotally attaching the dipper handle at the end remote from the dipper to a universal joint associated with said stick and the secondary boom of said shovel, said dipper handle comprising a yoke pivotally attached to the universal joint which in turn is pivotally attached to the secondary boom, said stick comprising a pair of detachably mounted members extending forward from the main body of the stick and comprising bearing means for supporting a shaft upon which said universal is mounted, said forwardly extending members comprising a track lying below said bearing means, a cross member on the end of said link, rollers on the ends of the cross members, said rollers being engaged with said track, said track and cross members comprising a variable pivot means for said link, a yoke attached on the end of said dipper handle mounted at right angles to said shaft in said bearing means, said yoke comprising a guide track, a second cross member on said link associated with the guide track for guiding the vertical movement of the link, a passage through said dipper handle to permit said link to pass diagonally therethrough in a direction generally downward and forward, thereby providing a more rapid travel of the forward part of the dipper than of the rear part of the dipper when it is elevated or lowered.

6. In a mobile power shovel of the knee action type comprising a dipper filled by a forward stroke and emptied through a door in the rear, said dipper being attached to a dipper handle, said dipper handle being pivotally mounted remote from the point of attachment to said dipper on a secondary boom and a thrust stick assembly by which it may be thrust forward or retracted, a primary boom and a hoist for elevating the dipper, the improvement which comprises means for pivotally attaching the dipper handle adjacent the rear of the dipper to permit vertical pivoting, a tilting link pivotally attached adjacent the front of the dipper likewise mounted to permit vertical pivoting, said tilting link being pivotally associated with said secondary boom and thrust stick assembly at a point adjacent the point of pivotal attachment of the dipper handle with said secondary boom and stick assembly, but lying between the latter point and the point of attachment of the dipper handle to the dipper thereby providing more rapid travel upward of the nose of said dipper than of the rear part of the dipper while it is being elevated and more rapid travel of the nose of the dipper downward when the dipper is being lowered.

7. The apparatus of claim 6 wherein the pivot point of the link associated with the secondary boom and stick assembly is fixed.

8. The apparatus of claim 6 wherein the pivot point of the link with the secondary boom and stick assembly is movable.

9. In a power driven shovel having a dipper filled by a forward thrust and emptied through a door in the rear comprising a dipper attached to a dipper stick the improvement which comprises means for pivotally attaching the dipper stick to the dipper and means for increasing the rate of travel of the nose of the dipper relative to the rear of the dipper during elevation or lowering of said dipper, said means comprising a link pivotally attached to the dipper and to the shovel, said link crossing said stick.

WALTER A. HILGEMAN.

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

UNITED STATES PATENTS Number Name Date 1,057,457 Rood 1 Apr. 1, 1913 1,288,514 Clutter Dec. 24, 1918 1,703,063 Dorward Feb. 19, 1929 1,857,302 Hawkins May 10, 1932 2,106,402 Carlesimo Jan. 25, 1938 2,139,254 Bixby Dec. 6, 1938 2,139,255 Bixby Dec, 6, 1938 2,303,852 Linn Dec. 1, 1942 2,379,876 Bradley July 10, 1945