Abstract:
An excavator dragline bucket is supported by a hoist line from a dragline power unit, and pivots about the connection of the hoist line to the bucket. The bucket is designed to dump toward the rear, and has a gate that is latched in position during the loading of the bucket, and which will be automatically unlatched as the bucket tilts rearwardly. The gate is connected through a double pivoting bellcrank that is operated by control links connected to the hoist member such that as the angle between the bucket and the hoist member changes, the control link loads the double pivoting lever and releases the latch. When the bucket has been dumped and is returned to its horizontal position, the tailgate first moves against the rear edges of the bucket, and subsequently the double pivoting lever permits the tailgate to slide along its plane to a latched position.

Description:
This application claims the benefit of U.S. Provisional Application No. 60/098,849, filed Sep. 2, 1998. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to a rear dumping dragline bucket and rigging system (rear dumping dragline bucket) that has a tailgate that will be released/opened when the bucket is tilted rearwardly enough so that the rigging is oriented in a selected manner, and which will be automatically reset when the bucket returns to its operative position. 
     Various rear dumping dragline buckets have been advanced in the prior art. An early excavating bucket which had a latched door at the rear end is illustrated in U.S. Pat. No. 955,285. This patent, however, had a single latch in the center of the door, and utilized a separate arrangement whereby the bail on the bucket, which was pivotally mounted and attached to the hoist line, would pivot forwardly and have a latch dog member that engaged a bellcrank, which in turn operated on a link that hooked another bellcrank which was used to lift the latch to undo the rear door. It is apparent that the total pivoting of the bail required a substantial amount of movement of the bucket, into a vertical position, before unlatching, and the use of mechanically engageable members would be likely to be unreliable. 
     U.S. Pat. No. 1,118,724 also shows a shovel bucket that has a rear dump door controlled by a rather complex latch that is operated through a lever and chain arrangement. The chain is driven by a separate sheave that would be rotated to pull the chain and release the latch. 
     Various other buckets that have rear dumping capabilities with doors that are latched during loading and swing, and unlatched by various apparatus have been advanced in the art, but a fully reliable arrangement that provides for essentially automatic operation on a fool-proof basis has been lacking. A bucket which permits rear dumping, but without a separate door is shown in U.S. Pat. No. 5,400,530. 
     A rear dumping dragline bucket will increase the efficiency of operation of a dragline by permitting discharging overburden at a greater dump radius distance from the dragline power unit and depending on individual hoist rigging requirements, at a higher height than with a forward dumping bucket and rigging system. A need thus exists for a reliable rear dumping bucket. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a reliable Rear Dumping Dragline Bucket that is provided with a double-hinged rear door or gate to ensure that the bucket can be adequately loaded, and with an automatically operated latch for releasing the gate during the dumping cycle. A unique lever arrangement is tied in with the hoist line rigging in the present invention so that the rear gate releases reliably, and the latch is made to ensure that when the bucket is returned to its operating position, the gate will be permitted to swing closed against the rear bucket&#39;s sidewall and floor/bottom edges and latch reliably. 
     Specifically, the present invention relates to a Rear Dumping Dragline Bucket that has a rear gate that is mounted onto the rear sidewalls of the bucket adjacent to the top edges, through a pair of double pivot lever (bellcrank) arrangements, so the end gate can be lifted essentially parallel along the plane of the bucket sidewalls for unlatching during initial movement of the levers, and permitted to swing outwardly about the second pivot of the lever when the dragline bucket moves to a dumping position. 
     The operating linkage is a cable or chain attached to the bucket hoist chain spreader bar, that will provide tension load on the double pivot levers as the rear dump bucket is permitted to tilt rearwardly for dumping. 
     A tagline is utilized for controlling the angular position of the plane of the bottom of the bucket relative to the ground, or in other words, a horizontal level control is exerted by the tag line. The rigging includes a spreader bar on the hoist chains, as shown. The exact mounting of the hoisting chains is not critical to the performance of the end gate used for rear dumping. 
     The rigging shown is by way of illustration, and again various types of tag lines can be utilized, as well as different operating linkages for moving the double pivoting levers for releasing the end gate from the latches and permitting it to swing open. 
     The rear dumping bucket of the present invention provides the advantages that are present in previous rear dumping buckets; that being of discharging overburden at a farther distance from the dragline power unit and possibly at a great dump height than conventional forward dumping buckets. Additional, the present invention will increase productivity through a reduction in both the loading and dump cycles. This is accomplished due to: (1) The ability to hoist a loaded bucket closer to the dragline&#39;s boom point, thus reducing the loading cycle and (2) a quicker dumping bucket as a result of the rear dumping dragline bucket and rigging system. The rear dumping bucket and rigging system will permit excavating a deeper and/or wider pit while increasing the effective load from each bucket hoisted, as compared to a conventional front dumping bucket. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevational view of a rear dumping bucket having an end gate made according to a first form of the present invention installed thereon; 
     FIG. 2 is a front perspective view of the bucket of FIG. 1; 
     FIG. 3 is an enlarged rear view of the bucket of FIG. 1; 
     FIG. 4 is an enlarged rear view of a bellcrank actuator used with the end gate of the present invention; 
     FIG. 5 is a fragmentary enlarged side view of the rear portion of the bucket of FIG. 1 showing the latches used with the present invention; 
     FIG. 6 is a fragmentary enlarged top view of a latch used for the end gate of the present invention taken on line  6 — 6  in FIG. 5; 
     FIG. 7 is a side view illustrating the rear dump bucket pivoted rearwardly so the double pivot lever has lifted the end gate to unlatch it; 
     FIG. 8 is a side view showing the bucket of the present invention in a full dumping position, with the end gate swung open for dumping material out of the rear of the bucket; 
     FIG. 9 is an enlarged side view of a latch shown with the end gate approaching a latched position after dumping as the bucket is being moved to is working position; 
     FIG. 10 is a side elevational view of a dragline bucket having an end gate latch made according to a second form of the present invention in a position similar to FIG. 7; and 
     FIG. 11 is a fragmentary enlarged side view of the latch shown in FIG.  10 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A bucket illustrated generally at  10  is a dragline bucket that is formed with sidewalls  12 , a floor  14 , and excavator teeth  16  at the forward end of the floor in a conventional manner. Cheek plates  18  are mounted at the forward ends of the sidewalls  12 , and provide for attachment of drag chains  20 . The drag chains  20  are attached through a common clevis  22  on which the drag cable  24  is attached. Drag cable  24  is controlled through a conventional set of drag cable sheaves on a dragline power unit  26  shown schematically. 
     The bucket  10  has hoist chains  30  pivotably mounted on brackets  32  using suitable connections, on each sidewall  12  in a selected position relative to the center of gravity of the bucket. A spreader bar  34  is connected to the top of the hoist chains  30 , and additional hoist chains  36  extend up from the spreader bar  34  to a clevis  40  that attaches to a hoist cable  38  through a cable termination end  38 A. A housing  39  is supported on clevis  40  and supports a rotatable tag line sheave  41 . The sheave  41  is spaced a desired amount above the spreader bar or equalizer bar  34 . 
     The bucket  10  has an end gate or tailgate assembly  44  mounted at the rear end of the bucket, to close the space between the sidewalls  12 . The end gate  44  is partial height, but it will enclose the end of the bucket  10  and extend from the floor  14  up a desired amount to permit filling the bucket adequately. The end gate  44  can be suitably reinforced, and carries latchbars for holding the end gate closed. Side frame members  45  are supported onto a top cross frame member  45 A (see FIG. 3) and are to the outside of walls  12 . Pivot pins  46  on the opposite sides of the bucket hold upper ends of the side frame member  45  at first pivot points of bell crank-type levers  48  on each side of the bucket  10 . The bellcranks  48  are mounted on pivot pins  49 , which are supported on suitable ears  12 A that extend upwardly above the upper edges of the major portion of the sidewalls  12 . Bellcrank levers  48  each have an arm actuator  54  that extends upwardly, on each side of the bucket, and the arms  54  are each connected to a suitable chain or cable  56  on each side of the bucket  10  forming flexible links. The chains or the cables  56  in turn are adjustably fastened to the spreader bar or equalizer bar  34 . The bellcranks  48  also each have an end gate actuating arm  58  that is positioned between the pivot pins  46  and  49 , and which is forwardly of the end gate  44  and frame members  45 , which align with the side frame member  45 . 
     The end gate  44  carries a pair of latch assemblies  42  thereon, one to the right and one to the left and these latch dog assemblies  42  comprise tubular latch dogs  43 A and  43 B which are pivotally mounted as at  47 A and  47 B on the rear wall panel  50  of the end gate  44 . The panel  50  is a solid steel panel that is supported by a framework including cross member  45 A and tubular frame end uprights  45 C and  45 D for reinforcements in desired locations. The latch bars  43 A and  43 B have circular cross sections and end portions  51 A and  51 B which extend laterally out through slots  53 A and  53 B the frame side uprights. The end members are guided in suitable guide or wear straps, one of which is shown at  53 C in FIG. 9 so that they can move up and down generally as indicated by the arrows  53 F. 
     The end portions  51 A and  51 B are made to fit into latch plates  60 A and  60 B that are mounted on the outsides of the side walls  12 , and have rounded hook ends  61 A and  61 B that define a notch  62 A and  62 B, respectively. There is a wide slot  63 A and  63 B that is milled into the side of the respective latch plate which will receive the end portions  51 A and  51 B. The slots are shown in FIG. 6 at  63 B, and there is another slot  63 A on the opposite side on the latch member  50 A as seen in FIG.  3 . 
     The rounded ends  61 A and  61 B are made so that they will provide an inclined surface such as that shown at  61 C in FIG. 9 for lifting the latch dog end portions  51 A and  51 B as the tail gate  44  moves toward a closed position. The latch dog end portion  51 A and  51 B will slide down into the slots  63 A or  63 B of the respective latch plates,  60 A and  60 B, and the end gate will be held in the locked, closed position. The end gate  44  provides a closed rear end wall for the dragline bucket so that the dragline bucket can be filled full, prior to dumping, and then the end gate can open for dumping after it is actuated. The notches  62 A and  62 B are provided so that the bucket and end gate are skewed as the end gate closes, the latch dog end portion s will be held in the open notches, even if an end portion does not slide into the provided slot. 
     The bucket  10  is provided with a rear cross bar or tube  66 , that braces the sidewalls  12 ,  12  and keeps them in proper position, as well as providing structural strength for attachment of a tag line cable or chain  68  as shown at  70 , on the cross bar  66 . The attachment  70  can be a bracket, clevis, or made by wrapping the cable onto the crossbar using a cable clamp. 
     The rigging shown is all that is necessary for operating the rear dump bucket of the present invention using the unique end gate latching arrangement. When the bucket  10  is filled in a normal manner by exerting a load on the drag cable  24 , through the action of the excavating teeth  16  and the normal weight of the bucket, while the hoist line  38  is slackened sufficiently, the hoist line  38  is then tensioned to raise the bucket  10  using the power unit  26 , and the bucket  10  will be hoisted and swung to its dumping location. Tension on the drag cable  24  will be controlled to maintain the bucket  10  in the proper orientation about the pivots formed at the brackets  32  holding the hoist chains  30  in place. The pivot axis formed by brackets  32  is positioned ahead of the center of gravity of the bucket  10 , either empty or loaded so the bucket tends to pivot rearwardly. That is so the rear of the bucket will drop when the drag cable  24  is slackened. The load on the cheek plates from the drag cable  24  controls the load tending to pivot the bucket. 
     When the bucket  10  is at its desired dumping position, the drag cable  24  will be relaxed or slackened, so that the bucket  10  will pivot to lower the rear, and when in a position shown in FIG. 5, the link  56  tightens and further pivoting will cause the links to pull on the levers  54 , which pivot about pivots  49  on the bucket wall portions  12 A. At the same time, the pivot of  46  of the bellcrank  48  will be moved substantially parallel along the plane of the bucket sidewalls  12 . 
     When the bucket pivots to the position shown in FIG. 7, the movement of the bellcranks pivot  46  is sufficient along the plane of the bucket sidewalls  12  so that the latch dog end portion  51 A and  51 B are pulled out of the slots  63 A and  63 B and the notches in which they are resting in the latches  60 A and  60 B and the end gate  44  then is unrestrained insofar as its lower edge is concerned. The end gate can then pivot about the axes of the pivot pins  46 , which are on the bellcranks  48  mounted on opposite sides of the bucket. The end gate opens and the load is dumped as the drag cable slacken more. 
     Referring to FIGS. 5 and 7, it can be seen that the arms  58  have a bearing plate  59  that engages the forward surface of the upright frame members  45  of the end gate  44 . As stated, the upright frame members  45  are on the outside of the sidewalls  12  and align with the arms  58 . The bellcranks  48  will also pivot the end gate frame members  45  and the end gate assembly  44  outwardly when the bucket tilts toward its full dumping position which is shown in FIG.  8 . The force from the arms  58  and the plates  59  ensures timely opening of the end gate  44  even if the load does not slide easily. 
     It can be seen in FIGS. 5 and 8 that the tag line  68  moves sufficiently as the drag cable  24  is slackened to let the rear end of the bucket move downwardly for dumping. The drag chains become slack. As shown in FIG. 8, the arms  58  and the reaction pads  59  engage the frame members  45  of the end gate to ensure that the end gate will not swing closed too early, as the bucket is moved back to its working or loading position. 
     The bucket, when empty, will be swung back towards it loading position, and the drag cable will be tightened, thereby causing the tag line  68  to pull the rear end of the bucket upwardly, and the control links or cables  56  will permit the bellcrank  48 , and the lever end gate  54  to move counter clockwise as shown in FIG. 8 so that the end gate  44  will move back to its position shown in FIG. 5, on its way toward its closed position. 
     When the end gate  44  moves to the position shown in FIG. 9, the latch dog ends  51 A and  51 B will strike the ramps  63 C of the latch plates  60  and pivot about the pivots  47 A and  47 B so they will align with and seat in latches  65 A and  65 B. Further movement of the rear portion of the bucket upwardly about the pivot axis of the pins  32  will permit the ends of the latch dogs  51 A and  51 B to slide downwardly into the slots  63 A and  63 B. The end gate  44  is again locked into usable or closed position. When the bucket  10  reaches its working position, the hoist line  39  will have been lowered sufficiently so that the bucket will engage the ground, and the drag chain will then pull the bucket  10  forwardly for loading in a normal manner. 
     The length of the end gate control links  56 , which can be chains or cables, will determine the point at which the bellcrank  48  operates to lift the end gate  44  and release from the latch members. The links  56  are adjustable in length, either by removing or adding one or more chain links, or by using cable and adjusting the length of cable by changing the attachment points. The links  56  may be attached to lever arms with adjustable directly. Preferably, the rearward tilt of the floor of the bucket will be in the range of about 15° to 30° from the horizontal before the links  56  are tight. Adjustment holes for attachment of links  56  to the links arms  54  are for changing the lever arm length. The effective lever arm between the pivot  49  and the pivot  46  of the bellcrank, as well as the length of lever arm  54  can determine the force with which the end gate  44  is lifted from the latch members  60 A and  60 B. A high “breakout” force can be avoided by regulating the relationship of the lever arms. The effective lever arm on a line between pivot  49  and the pivot  46  is slightly greater than 90° with respect to the plane of the end gate, in the closed position as shown in FIG. 1, in order to minimize the “in and out” effect of the arc on the pivot point  46 , and give a maximum movement for releasing the latch dog end portions  51 A and  51 B during this initial unlatching movement of the bellcrank  48 . Approximately a 3:1 ratio between the length of the effective lever arm at the junction of the link  56  and the lever  54  to the pivot point  49  as compared of the length between pivot point  49  and pivot point  46 , is provided. 
     In a second form of the latch used with the present invention, shown in FIGS. 10 and 11, end gate  94  has a pair of latch dogs or pins  96  on each side of the end gate which protrude downwardly from the bottom of the end gate. The end gate can be made as before, but the pivoting latches  42  are removed and the latch plates  60 A and  60 B are also removed. In this form of the invention the latch dogs  96  are like round pins, that are made to fit into openings  99  in latch plates  98 . Latch plates  96  mount on the lower ends of the sidewalls, and align with the latch dogs  96 . The opening in plates  98  receive the latch dogs, so that when the end gate is in the position as shown in dotted lines in FIG. 11, the end gate  94  is locked closed and will provide a closed end for the dragline bucket so that it can be filled full prior to dumping. The bucket and rigging are constricted as before and are numbered identically in FIGS. 10 and 11. The filling of the bucket and unloading swing is as in the first form of the invention, and when in position, the drag cable is slackened as described before. As this happens, the lines or links  56  tighten, pulling on the lever arms  102  of bellcranks  100  that are constructed as before. The bellcranks  100  are pivoted as at  104  to the sidewalls  12  of the bucket  10  and are pivoted to the end gate  94  at pivots  106 . As the bellcranks  100  pivot about the pivot  104  on the bucket, the pivot  106  moves substantially parallel along the plane of the sidewall  12 . The movement of the bellcrank pivot  106  is sufficient along the plane of the sidewalls  12  so that the latch dogs  96  are pulled out of the openings  99  in which they are positioned in the latch plates  98 , and the end gate  94  then is unrestrained insofar as its lower edge is concerned and can pivot about the axis of the pivot pins  106 , which are on the bellcranks  100 . 
     The operation of the bucket is the same as in the first form of the invention, except the latches are different. 
     Various types of latches can be used, of course, including spring loaded latches that would yield for resetting, and be released in the same manner as the present operation, except that instead of lifting the gate, the bellcrank levers could lift the latch members. 
     Also, different types of latches can be used for the end gate itself, including latches along the sides of the end gate, or along the bottom edges and toward the center. The direct acting bellcrank that lifts the end gate as shown in the disclosed embodiments of the invention has substantial advantages. 
     The breakout force needed for releasing the end gate can be changed by changing the lever arrangement. 
     Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.