WO 00/41956 PCT/US99/02519 PUSHER ELEMENTS FOR PACKAGE SORTATION CONVEYORS 5 10 TECHNICAL FIELD The invention relates to improved pusher elements for sortation conveyors and the like, and more particularly to right-hand, left-hand, and right and left-hand divert 15 pusher elements having improved carton lifting or ramping qualities and carton contacting bumpers of increased surface area. BACKGROUND ART While the pusher elements of the present invention may have other applications as in diverter conveyors and combiner conveyors, for purposes of an 20 exemplary showing the pusher elements of the present invention will be described in their application to a package sortation conveyor. This is for convenience only, and is not intended to be a limitation of the present invention. In its most typical form, a sortation conveyor comprises two sets of side frame elements which are joined together by appropriate transverse braces. Most usually, 25 the conveyor is supported on a floor by appropriate leg members. The moving conveying surface of the conveyor may, for example, comprise a pair of endless chains passing about sprocket sets at the conveyor ends and powered by one of the sets of sprockets. Attached to the chains are a plurality of transverse members which constitute the actual package supporting conveyor surface. The transverse members 30 are relatively close together and may take various forms. Circular cross-section tubular members are frequently used for this purpose. Tubular or solid members having other peripheral shapes (such as slat-like members) are also frequently used.
WO 00/41956 -2- PCT/US99/02519 The conveyor just described will have one or more side outlets on one side only, or on both sides. A plurality of pusher elements are mounted on selected ones at least of the transverse members and are slideable along their respective transverse members. Thus, the pusher elements travel in the same direction as the tubes or slats 5 making up the conveyor's conveying surface. In addition, however, the pusher elements are capable of shifting along their respective tubes or slats transversely of the conveying surface and shoving a particular package from the conveying surface through a pre-selected outlet. The one or more outlets may, of course, lead to additional conveyors. 10 The precise nature of the conveyor and its conveying surface do not constitute limitations of the present invention. For purposes of an exemplary showing, the pusher elements of the present invention have been shown in their application to a package sortation conveyor of the type taught and illustrated in U.S. Patent 4,711,341. As will be apparent hereinafter, the conveying surface is made up of a plurality of 15 transverse tubular members affixed to an endless chain at either side of the conveyor frame. Each pusher element is provided with a mount that slidably engages two adjacent tubular members of the conveying surface. Within the conveyor frame, below the conveying surface, mechanisms are provided to cause a predetermined number of pusher elements to shift at a particular position with respect to the 20 conveyor frame, (i.e. toward a side outlet) and at a particular time, all as will be apparent hereinafter. While sortation conveyors are highly successful and widely used, they sometimes encounter a problem generally known in the art as "scissoring". This is usually the result of a pusher element contacting a misplaced package, the forward 25 motion of which has been impeded for some reason. For example, the package may be caught or trapped between an actively diverting pusher element and a trailing pusher element from a previous diverting operation. Another example is found in an instance where movement of the package along with the conveying surface is impeded because the package has struck the downstream edge of a branch outlet. A 30 package under either of these situations may be contacted by a number of successive pusher elements. This can, of course, cause damage to the package and to the pusher WO 00/41956 PCT/US99/02519 -3 elements, themselves. As a result, prior art workers have expended both time and effort to improve the shape of the single and dual directional diverting pusher elements in an effort to assure that if a pusher element encounters an out-of-place package which is blocked for some reason against movement along the conveyor, the 5 pusher element will pass beneath the package in order to reduce damage to the package and the pusher element. The efforts in this area have been reasonably successful, but there is room for improvement. The present invention is directed to diverting pusher elements in three related embodiments. The present invention contemplates left-hand diverting pusher 10 elements, right-hand diverting pusher elements, and dual direction diverting pusher elements capable of pushing a package in a left-hand or right-hand direction. The single direction left-hand and right-hand diverting pusher elements are mirror images of each other. The dual directional diverting pusher element is, for the most part, a combination of the single directional pusher elements. 15 It is therefore an object of the present invention to provide embodiments of pusher elements characterized by larger bumpers having increased area for engagement of a package to be diverted, to help assure that the package moves in the desired direction. It is an object of the present invention to provide three embodiments of pusher 20 elements having improved package lifting characteristics. It is an object of the present invention to provide three embodiments of pusher elements which have a front apron having two angularly related surface portions, one above the other, enabling the pusher elements to plow under and lift out-of-place packages. This also allows for a larger bumper. 25 It is an object of the present invention, in all embodiments thereof, to provide an upward extension of the apron adjacent the bumper so as to feed out-of-place cartons over the ribs of the pusher element bodies.
WO 00/41956 PCT/US99/02519 -4 It is an object of the present invention to provide ribs on the pusher element bodies (all three embodiments) not only to strengthen the bumper mounting system, but also to additionally serve as package lifting elements. It is an object of the present invention, in all embodiments to provide a relief 5 at those apron edges which are adjacent a bumper. This increases the lifting power applied to a package which is contacted by such an edge. It is an object of the present invention to provide pusher elements of each embodiment with at least one portion which overlaps a part of the apron of the adjacent following pusher element. The adjacent following pusher element has, 10 formed in its apron, a notch to receive the overlapping portion of the adjacent pusher element during its passage through the cantenary portion of the return flight of the conveyor surface so that adjacent pusher elements tend to "lock-up" to eliminate rattle. These notches also provide clearance for the enlarged bumper surfaces. It is an object of the present invention to provide the bumpers with surface ribs 15 angled at about 30 degrees to the longitudinal direction of travel of the bumper. These ribs reduce carton slippage, tend to keep the bumper surfaces clean, and also tend to urge the cartons downward against the conveyor surface. It is an object of the present invention to provide the single-directional diverting pusher elements with large radius corners opposite their bumpers. 20 It is an object of the present invention to cause that side of a unidirectional pusher element, opposite the bumper, to extend below the tubing support surface when the conveying surface is made up of circular cross-section tubes. It is an object of the present invention to recess the surface of the non-divert side of a single direction pusher element directly above the tubes constituting the 25 conveyor surface, in order to avoid carton hang-ups. It is an object of the present invention to provide three embodiments of pusher elements, the molding of which lends itself well to modular tooling techniques.
WO 00/41956 5 - PCT/US99/02519 It is an object of the present invention to provide an improved removable attachment of the bumper to the body of the pusher to maintain the bumper package contacting surface substantially planar. It is an object of the present invention to provide bumpers of wedge shape 5 cross-section to achieve different angularities of the bumper surface with respect to the conveyor surface direction. DISCLOSURE OF THE INVENTION According to the invention there is provided single and dual direction diverting pusher elements for sortation and other appropriate conveyors. The pusher 10 elements are provided in three embodiments, a right-hand diverting pusher element and a left-hand diverting pusher element, each of which is a mirror image of the other. The third embodiment is a dual direction diverting pusher element. This pusher element is substantially a combination of portions of the single direction pusher elements. 15 All embodiments of the pusher element have bumpers which are enlarged in height, length, and pushing surface area and which are ribbed in such a way as to prevent slippage and to urge a package downwardly against the conveying surface. The ribs also soften any impact to the carton corner or side. Each pusher element has a forward apron-like surface which slopes upwardly 20 from the horizontal and, about halfway up, slopes at a steeper angle providing maximum package lifting characteristics to avoid scissoring or the like. In a preferred embodiment, the apron surface comprises a large curved concave surface. Each pusher element is provided with ribs having upwardly sloping top surfaces. These ribs strengthen the bumper mounting portion of the pusher element 25 and also serve as lifting surfaces. The side surface of the front most rib constitutes an extension of the apron and tends to feed out-of-place cartons over the ribs. To further increase package lift characteristics, the edge of the apron adjacent a bumper is provided with a lifting relief.
WO 00/41956 PCT/US99/02519 -6 Each of the three embodiments of pusher elements may be provided with additional features to improve performance as will be set forth hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a top, left side, perspective view of an exemplary prior art 5 conveyor provided with pusher elements. Figure 2 is a fragmentary top plan view of the conveyor of Figure 1, provided with pushers of the present invention. Figure 3 is a right side, front and top perspective view of a right-hand pusher element. 10 Figure 4 is a top plan view of the pusher element of Figure 3. Figure 5 is an elevational view of the pusher of Figure 3 as seen from the top of Figure 4. Figure 6 is an elevational view of the pusher element of Figure 3 as viewed from the bottom of Figure 4. 15 Figure 7 is a front elevational view of the pusher element of Figure 3, as seen from the right of Figure 4. Figure 8 is a rear elevational view of the pusher element of Figure 3 as seen from the left of Figure 4. Figure 9 is a bottom view of the right-hand pusher element of Figure 3. 20 Figure 10 is a top plan view of a left-hand pusher element of the present invention. Figures II and 12 are plan views of right-hand pusher elements illustrating - how the angle of the bumper surface to the direction of travel of the conveying surface can be changed by using wedge-shaped bumpers.
WO 00/41956 _ 7 _ PCT/US99/02519 Figure 13 is a top, front and right side perspective view of a double-sided pusher element. Figure 14 is a top plan view of the pusher element of Figure 13. Figure 15 is an elevational view of the pusher element of Figure 13, as seen 5 from the top of Figure 14. Figure 16 is an elevational view of the pusher element of Figure 13, as viewed from the bottom of Figure 14, with the bumper removed. Figure 17 is a front elevational view of the pusher element of Figure 13, as viewed from the right of Figure 14. 10 Figure 18 is a rear elevational view of the pusher element of Figure 13, as viewed from the left of Figure 14. Figure 19 is a bottom view of the pusher element of Figure 13. Figure 20 illustrates 3 adjacent left-hand pusher elements in the respective positions they would occupy along either side of the conveyer. 15 Figure 21 illustrates the relative positions of the left-hand pusher elements of Figure 20 during a transverse shift across the conveyor. Figure 22 is a plan view of the double-side pusher elements in the relative positions they occupy during a transverse shift across the conveyor. Figure 23 is a plan view of 3 adjacent double-sided pusher elements 20 illustrating their relative positions located at either side of the conveyor. Figures 24A through 24D diagrammatically illustrate various parts needed to make up all 3 of the pusher elements of the present invention. Figures 25A through 25C diagrammatically show the 3 pusher elements of the present invention, made up of the parts shown in Figures 24A through 24D.
WO 00/41956 PCT/US99/02519 -8 DETAILED DESCRIPTION OF THE INVENTION Throughout the drawings, like parts have been given like index numerals. Reference is first made to Figures I which illustrates a prior art conveyor with pusher elements such as is taught in U.S. 4,711,341. A main conveyor is generally indicated 5 at I and is fed packages by a feed conveyor generally indicated at 2. A branch conveyor is generally indicated at 3. Main conveyor I is made up of side frame elements 4 and 5 (see also Figure 2). Side frame elements 4 and 5 may be supported by legs, two of which are shown at 6 in Figure 1. It will be understood by one skilled in the art that the side frame 10 members 4 and 5 will have transverse braces (not shown) extending therebetween. On either side of the conveyor 1, there is an endless chain which passes about sprockets at either end of the conveyor. One set of these sprockets (usually the set at the discharge end of the conveyor), is driven and, in turn, drives the endless chains in the direction of arrow A. A series of transversely extending, conveyor surface 15 forming members are attached at their ends to and between the endless chains. As indicated above, these conveying surface elements may constitute tubular members having a circular cross-section or slat-like members providing a flat support surface making up the conveying surface. For purposes of an exemplary showing, the conveying surface, generally indicated at 7, is made up of tubular members 8 arranged 20 in parallel spaced relationship with their ends affixed to the chains 9 and 9a (see Figure 2). In Figure 1, a series of cartons are shown on the feed conveyor 2 at 10. Two packages 11 and I Ia are being conveyed by conveyor surface 7 of main conveyor 1. Two additional packages 12 and 13 are past the side conveyor 3 and are continuing in the direction of arrow A on the conveying surface 7 of main conveyor 1. 25 Two packages 14 and 15 have been diverted to side conveyor 3. Obviously, package 14 was originally located between packages 13 and 12 and was moved onto side conveyor by the set of right hand divert pusher elements generally indicated at 16. A set of right hand divert pusher elements 17 have caused package 15 to be diverted onto side conveyor 3. It will be noted that the last two pusher elements of set 17 are 30 still shifting package 15. Since neither package 12 nor 13 have been diverted, the WO 00/41956 PCT/US99/02519 -9 pusher elements generally indicated at 18 and 19 across from these sets are still in their original, unshifted position along the left hand side frame 4. As a matter of convention, the right side and the left side of the conveyor frame are determined when looking down the conveyor in the direction of travel of 5 conveying surface 7. Thus, side 4 is the left side of the conveyor, side 5 is the right side of the conveyor, and the pushers shown in Figures 1 and 2 are single direction right hand pushers. A conveyor of the type shown in Figures 1 and 2 could be set up on a predetermined pattern. For example, conveyor may automatically divert every other 10 package. On the other hand, packages may be diverted in response to signals from bar code readers. Therefore, a package will be diverted only if its bar code indicates that it should be diverted. Between the upper conveying flight and the lower return flight of conveying surface 7 conveyor 1 is provided with appropriate switches, channels and bars which appropriately shift a series of pusher elements when needed. 15 The shifting mechanism is well known in the art and an example of such mechanism is taught in U.S. Patent 4,711,341. Additional shifting mechanism is provided for the return flight so that all of the pusher elements are in their "home" position along the left side of conveyor I as they start their travel along the conveying flight of conveying surface 7. 20 If all of the side conveyors were associated with the left side of main conveyor 1 (rather than the right side as in Figures 1 and 2) then the conveyor would need a series of left side diverting pusher elements, the home position of which would be along the right side 5 of conveyor 1. The operation, of course, would be substantially the same. 25 In some instances, the main conveyor may have side conveyors extending from both of its sides. In this instance, dual direction diverting pusher element would be desirable. Such diverter elements would be capable of diverting a package either to the right or to the left.
WO 00/41956 PCT/US99/02519 -10 Reference is now made to Figures 3 through 9 wherein a right hand pusher element is illustrated. For a better understanding of the pusher element, it is again pointed out that Figure 4 is a top plan view of the right hand pusher element generally indicated at 18. In Figure 4, the direction of movement of the conveying surface and 5 the pusher 18 as it moves therealong, is again indicated by arrow A. Movement of pusher 18 transversely of the conveying surface is indicated by arrow B. Figure 5 is a left side elevational view as seen from the top of Figure 4, while Figure 6 is a right side elevational view as seen from the bottom of Figure 4. Figure 7 is a front view as seen from the right of Figure 4, while Figure 8 is a rear view as seen from the left of 10 Figure 4. The body of pusher element 18 preferably comprises an integral, one-piece, molded structure made of an appropriate plastic material such as rubber modified polypropylene. The forward end of pusher element 18 has an apron 19 which faces the 15 direction of travel A of the conveyor surface. Apron 19 has a lower portion 20 and an upper portion 21 with a transition portion22 therebetween. The lower portion 19 of the front apron extends approximately half way up the apron and lies at an upwardly sloping angle of about 35 degrees. Passing through the transition portion 22, the upper area 21 of apron 19 lies at an angle of about 40 degrees. The arrangement is 20 such that the apron portions 20 and 21 approximate a 13" radius rendering the apron substantially concave. It will be apparent (particularly from Figures 4 and 6) that the apron has an extended portion 23 which continues to the top of bumper support 24. The apron extension 23 will lift out-of-place cartons over the bumper support 24 and the ribs 25, 26 and 27 which extend therefrom, as will be described hereinafter. 25 The right side edge 28 of the apron, extending up to bumper support 24, is relieved as at 29. The relief 29 constitutes a lifting surface, should pusher element 18 contact an out-of-place carton at the end 28 of apron 19. It will be noted that the apron and its extension has a notch 30 formed therein. This is a clearance notch, as will be explained in detail hereinafter. At its left hand end, apron 19 extends in a 30 large curve 31 about the left front corner of pusher element 18, passing along the left WO 00/41956 PCT/US99/02519 side of pusher 18 and terminating in a large curve 32 extending toward the rear of pusher element 18. Apron 19, except at its extension 23, leads to a horizontal surface 33. The horizontal' surface 33 extends between ribs 25 and 26 and between ribs 26 and 27. It 5 will be noted that ribs 25, 26 and 27 extend from the bumper support wall 24 to the horizontal surface 33, and, in part, serve as support for bumper mounting wall 24. Each of the ribs 25 through 27 have a top surface which can also act as a lifting surface to lift an out-of-place carton over bumper support wall 24. The bumper 34 can be affixed to bumper wall 24 in any appropriate manner. 10 Conventionally, bumper 34 is provided with an outer portion35 having an outer rib surface and an inner portion 36 arranged in parallel spaced relationship with outer portion 35, as shown in the bottom view of Figure 9. The inner portion is connected to the outer portion of bumper 34 by webs 37, 38, 39 and 39a. The outer and inner portions 35 and 36, and the webs 37, 38, 39 and 39a define vertical sockets in bumper 15 34. As is most clearly shown in Figure 8 at 43, and in Figure 9, the outer surface of bumper supporting wall 24 is inset, forming a longitudinal flange along its upper edge. Depending from this flange there are tabs 44, 45 and 46 which are received in the bumper sockets 40, 41 and 42, respectively, and hold the bumper 34 in place. As 20 is perhaps best shown in Figure 6, bumper 34 is provided on its outer surface with ribs 47. Ribs 47 form an angle with the bottom edge of bumper 34 of about 30 degrees. The 30 degree angles open in the direction of movement of the conveying surface, again indicated at arrow A. The ribs serve to cushion the impact of the bumper against a carton. The ribs also reduce carton slippage, stay clean and tend to urge the 25 carton they contact downwardly against the conveying surface. It will be understood by one skilled in the art that the mounting means for the pusher elements of the present invention can take any appropriate form. With proper mounting means, the pusher elements can be slidably affixed to transverse tubular elements of circular cross-section or to slat-like elements. While the nature of the WO 00/41956 -12- PCT/US99/02519 conveying surface and the nature of the mounts for the pusher elements of the present invention do not constitute limitations of the present invention, for purposes of a complete description the pushers of the present invention are shown provided with a mount for a conveying surface made up of transversely extending tubular members of 5 circular cross-section. The mount is quite similar to that shown in the above mentioned U.S. Patent 4,711,341. The pusher element mount is generally indicated at 50 and is shown, for example, in Figure 6. The mount comprises a molded member 51 having a central body portion 52 and a pair of oppositely directed C-shaped portions 53 and 54. The 10 C-shaped portions 53 and 54 are of a diameter to just nicely and slidably receive an adjacent pair of tubes 8 making up conveying surface 7 (see Figures 1 and 2). Pusher element 18 includes on its bottom surface a downwardly extending portion 55 terminating in a metal plate 56 and located between upper portions of the C-shaped members 53 and 54. At the bottom of member 50 there is a metallic plate 15 57. A guide pin 58 extends upwardly through washer 58a, bearing 62, spacer 72a, plate 57, the body 52 of element 50, plate 56, and portion 55 of pusher element 18, surfacing in a depression 59 surrounded by a low annular sloping surface 33b on the flat top surface 33 of pusher element 18. The upper end of guide pin 58 is threaded and passes through a washer 60 and is threadedly engaged in a nut 61. Guide pin 58 20 and nut 61 do not extend above the annular sloping surface 33b of pusher shoe 18. Adjacent metal plate 57, guide pin 58 carries an anti-friction bearing 62, spacer 62a and washer 58a, in such a way that the bottommost portion of guide pin 58 extends therebelow. Bearing 62 and the lowermost portion of guide pin 58 cooperate with the mechanism of the conveyor that shifts the pusher element 18 across the conveying 25 surface. Two additional bolts 63 and 64 are provided. Bolt 63 and bolt 64 both pass through plate 57, the body 52 of mount 51, plate 56, and the portion 55 of the pusher element 18. Bolt 63 extends through pusher element 18 in a depression 65 in surface 33 and is provided with a washer 66 and a nut 67. Similarly, bolt 64 passes through 30 pusher element 18 in a depression 68 in horizontal surface 33. The bolt 64 passes WO 00/41956 - 13- PCT/US99/02519 through a washer 67 and is threadedly engaged in a nut 70. The bolt 63 and 64 and their nuts 67 and 70 do not extend above surface 33 of the pusher element. As is most clearly shown in Figure 6, apron 19 will extend below the top of a tube (not shown) located within C-shaped member 53. In fact the bottom surface of 5 apron 19 is configured to substantially continue the inner surface of C-shaped element 53. At its rearward end, a series of ribs 71 substantially continue the inside curvature of C-shaped member 54. As a result of this, C-shaped member 53 and the bottom surface of apron 18 will extend more than 180 degrees about a tube received in C shaped portion 53. Similarly, C-shaped member 54 and ribs 71 will continue more 10 than 180 degrees about a tubular member extending through C-shaped member 54. As a result of this, the mount 50 and its pusher element will be firmly affixed to the pair of tubes and will be slidable therealong. The mount and pusher element can only be affixed to and removed from the pair of tubes by sliding onto or off of the ends of the tubes. As is most clearly shown in Figures 4 and 5, that portion of skirt 19 which 15 extends along the left side of pusher element 18 (i.e. the non-divert side) has a pair of recesses 72 and 73 formed therein directly above the tubes which slidingly support the pusher element 18. This facilitates carton lifting when a carton approaches the pusher element 18 from its left side. Recesses 72 and 73 also enable that portion of apron 19 therebetween to have its bottom edge below the top surfaces of the tubes, as is clearly 20 seen in Figure 5. Figure 10 is a plan view of a left hand pusher element generally indicated at 18a. It will be understood by one skilled in the art that the left hand pusher element 18a is identical to the right hand pusher 18, with the sole exception that pusher elements 18 and 18a are mirror images of each other. As a consequence, the detailed 25 description of pusher element 18 may also serve as a description of pusher element 18a. In Figure 10, like parts have been given the same index numerals as in Figure 4, followed by "a". Referring to Figure 4 and to Figure 10, it will be noted that bumpers 34 and 34a both form an angle of about 21 degrees with apron edge 28 and apron edge 28a, WO 00/41956 PCTIUS99/02519 -14 respectively. The apron edges 28 and 28a are substantially parallel to the direction of motion of the conveying surface indicated by arrow A. Figures II and 12 illustrate how the angularity of the pushing surface of bumper 34 can be varied through the use of bumpers which are wedge-shaped in 5 longitudinal cross-section. In Figure 11, a right hand divert pusher element 18b is shown. Pusher 18b is identical to pusher 18 with the exception that the bumper supporting wall 24 lies at an angle of 25 degrees (rather than 21 degrees) to the direction of travel of the conveyor surface. Figure 11 illustrates a -5* wedge shaped bumper to provide a bumper contact 10 surface angled at 20 degrees with respect to the direction of travel of the conveyor surface. Figure 12 illustrates the same pusher element with a +5* wedge-shaped bumper to provide a bumper contact surface which forms an angle of 30 degrees to the direction of travel of the conveyor surface. If desired, other angularities can be achieved in substantially the same manner. It will be understood by one skilled in the 15 art that wedge-shaped bumpers can be used in exactly the same way with respect to left hand pusher element 18a. The same is true with respect to the dual directional pusher element, next to be described. Reference is now made to Figures 13 through 19 wherein the dual directional pusher element is illustrated. To assist in understanding the configuration of this 20 pusher element, it is again indicated that Figure 14 is a plan view of the pusher element. Figure 15 is an elevational view as seen from the top of Figure 14, while Figure 16 is an elevational view as seen from the bottom of Figure 14. It will be noted that a bumper has been removed from the pusher element in Figure 16. Figure 17 is a front elevational view as seen from the right of Figure 14, while Figure 18 is a 25 rear elevational view as seen from the left of Figure 14. In all of these Figures the dual directional pusher element is generally indicated at 74. As is most clearly shown in Figures 13 and 14, pusher 74 is provided with bumper support walls on either side of the pusher element as at 75 and 76. These walls support bumpers 77 and 78, respectively. Wall 75 is supported by ribs 79, 80 and 81 which extend down to a 30 planar surface 82 corresponding to planar surfaces 33 and 33a on the left hand and WO 00/41956 -15- PCT/US99/02519 right hand diverting pusher elements 18 and 18a. In a similar fashion, bumper support wall 76 is reinforced by a series of ribs 83, 84 and 85 which, again, extend to the horizontal surface 82. The ribs 79, 80 and 81 slope upwardly to the top of wall 75. Similarly, ribs 83, 84 and 85 slope upwardly to the top of wall 76. As a result of this, 5 these ribs not only provide support for walls 75 and 76, but also constitute lifting members for out-of-place cartons. Pusher element 74 has a front apron 86 which has a first surface portion 87 forming an angle of about 35 degrees with the horizontal. This first portion transitions smoothly into a second portion 88 which forms an angle of about 40 10 degrees with the horizontal so that the apron 86 demonstrates the excellent lift characteristics described with respect to the aprons of single directional pusher elements 18 and 18a. Since there are bumpers 77 and 78 on each side of pusher element 74, apron 86 has two extensions 89 and 90 on both sides of the pusher element. The extension 15 89 is similar to extension 23a of Figure 10. The extension 90 is similar to the extension 23 of Figure 4. Since there is no non-divert side with respect to pusher element 74, apron 86 ends in two edges 91 and 92. Edges 91 and 92 are provided with reliefs 93 and 94, respectively. Relief 93 is equivalent to relief 29a of Figure 10, while relief 94 is 20 equivalent to relief 29 of Figure 4, reliefs 93 and 94 serve the same purpose as reliefs 29a and 29. It will be noted that apron 86 has a pair of notches 95 and 96 formed therein. Notches 95 and 96 are equivalent to notches 30a and 30 of Figures 10 and 4. Again, the purposes of these notches will be apparent hereinafter. 25 As in the case of the right hand pusher 18 and the left hand pusher 18a, pusher 74 may be provided with any appropriate mount, depending upon the nature of the conveying surface (i.e. tubes, slats, or the like). Again, for purposes of an exemplary showing, the pusher 74 is shown provided with the same mount as pusher 18. To this end, like parts of the mount have been given the same index numerals. It will again WO 00/41956 PCT/US99/02519 -16 be noted from Figures 15 and 16 that the pusher element 74 is so configured that tubes located within C-shaped members 53 and 54 will be surrounded by more than 180 degrees requiring mounting and dismounting of pusher element 74 from the ends of the tubes of the conveyor surface. It will be noted from Figure 14, for example, that 5 the surface 82 has depressions 95, 96 and 97a formed therein. The depression 95 in surface 82 is surrounded by a low annular sloped area 82a, and accommodates guide pin 58, nut 61 and washer 60. Depression 96 accommodates bolt 64, washer 69 and nut 70. In a similar fashion, depression 97a in planar horizontal surface 82 accommodates bolt 63, washer 66 and nut 67. Guide pin 58 and its nut 61, bolt 63 10 and its nut 67 and bolt 64 and its nut 70 do not extend above horizontal surface 82. As is shown in Figure 19, the bottom of pusher element 74 is provided with appropriate reinforcing ribs. If it is decided to provide a mount usable with a slat, rather than a pair of tubular members, the bottom of pusher 74 will have to be modified accordingly. 15 Reference is now made to Figure 16. In this Figure, bumper 78 has been removed. In Figures 13 through 19, and 22 and 23 an alternate and preferred bumper mounting system is illustrated. It will be apparent that the new bumper mounting system could be applied to both the left hand diverting pusher element and the right hand diverting pusher element in the very same manner that it is applied to the dual 20 diverting pusher element 74. Reference is now made to Figure 16 wherein the wall 76 is shown without bumper 78. Wall 76 has formed near its upper surface a series of dovetail notches 97. Below the bottom of notches 97, wall 76 is recessed rearwardly as at 76a. In front of the recessed portion 76a there are a series of tabs or hangers 98, 99 and 100. 25 Bumper 78 has dovetailed lugs 101 received in the dovetail notches 97. The dovetailed lugs 101 cooperate with the dovetailed notches 97 to resist downward movement of the bumper and to resist movement of the bumper away from wall 76. As is shown in Figure 19, the lower portion of bumper 78 is of a thickness to extend all the way back to the recessed portion 76a of wall 76 and is provided with vertical 30 slots 102, 103 and 104 to receive tabs 98, 99 and 100, respectively. It will be WO 00/41956 PCT/US99/02519 -17 understood that bumper 77 is attached to pusher element 74 by the same attachment system. In fact, it is within the scope of the invention to apply bumpers similar to bumpers 77 and 78 both to the right hand diverting pusher element and the left hand diverting pusher element, using the same mounting system as just described. 5 The bottom view of Figure 19 shows a plurality of reinforcing ribs and supports the mount 50. It will be understood that the bottom of pusher element 74 may be appropriately modified to cooperate with other types of mounts, such as those used with a conveyor having a conveying surface made up of slats. Reference is now made to Figure 20. Figure 20 illustrates three left hand 10 pushers 18a in a row as they would line up in their unshifted or home position along the right side of a conveyor. They would line up in an identical manner on the left side of the conveyor, having been shifted across the conveying surface. Figure 21 shows the same left hand pushers as they would be aligned during a pushing operation. In the normal, non-pushing alignment, it will be noted that the 15 rearward end of bumper 34a overlies the notch 30a in apron 19a. On the flat upper flight of the conveyor surface, the rearward ends of bumpers 34a do not extend into notches 30a since the rearward ends of bumpers 34a are higher than the adjacent apron 19a. During the return flight of the conveyor surface and pusher elements, the 20 conveyor surface and pusher elements pass through a cantenary section wherein the conveyor surface is suspended in a relatively shallow reverse curve to take up slack. While in the reverse curve, the rearward ends of bumpers 34a will enter the clearance notch 30a of the following bumper element, engaging the bumper element in its clearance notch. This eliminates the rattling sound usually associated with a 25 cantenary section and the provision of the clearance notches 30a also enables the bumper surface to be maximized. It will be understood that the right hand pusher 18 of Figure 4 would align, mirror image fashion, in exactly the same way as illustrated in Figures 20 and 21. The rearward ends of bumpers 34 would cooperate with WO 00/41956 PCT/US99/02519 clearance notches 30 in precisely the same way, when passing through the cantenary section. Figure 22 illustrates three of the dual directional pusher elements 74 arranged as they would be during a left hand pusher operation, with bumpers 77 aligned. If the 5 pusher elements 74 were used for a right side pusher operation, their bumpers 76 would be aligned. Figure 23 illustrates the dual direction pusher elements 74 in their normal, unactuated alignment, which could be along either side of the conveyor. It will be noted that, in this alignment, the rearward ends of bumpers 77 and 78 overlie the 10 adjacent clearance notches 95 and 96 of the succeeding pusher element. As in the case of the single direction pusher elements of Figures 20 and 21, the ends of bumpers 77 and 78 are spaced upwardly away from their respective notches 95 and 96 when the dual direction pusher elements 74 travel along the upper flight of the conveyor. When the pushers 74 are in the return or lower flight of the conveyor surface, 15 they, as is true of the single direction pusher elements, will be subject to a reverse curve situation as they proceed through the cantenary section. In this situation , the rearward ends of bumpers 77 and 78 will enter clearance notches 95 and 96, respectively, reducing rattle. Again, it will be understood that by providing clearance notches 95 and 96 the bumpers 77 and 78 could be enlarged. 20 Reference is now made to Figures 24A, 24B, 24C and 24D. Figure 24A is a simplified, diagrammatic illustration of the pusher portion 105 of a left hand pusher element. Figure 24B is a simplified diagrammatic illustration of the pusher portion 106 of a right hand pusher element. Figure 24C is a simplified diagrammatic representation of the non-divert portion 107 of a right hand pusher element. Finally, 25 Figure 24D is a simplified diagrammatic representation of the non-divert portion 108 of a left hand pusher element. Figure 25A is a simplified diagrammatic plan view of a dual direction pusher element 74 (see Figure 14). Figure 25B is a simplified diagrammatic plan view of a WO 00/41956 PCT/US99/02519 -19 left hand pusher element 18a (see Figure 10). Figure 25C is a simplified diagrammatic view of a right hand pusher element 18 (see Figure 4). It will be immediately evident that the structure of Figure 25A constitutes the combination of part 105 of Figure 24A and part 106 of Figure 24B. The structure of 5 Figure 25B comprises a combination of the parts 105 of Figure 24A and 108 of Figure 24D. Finally, the structure of Figure 25C comprises the combination of part 107 of Figure 24C and part 106 of Figure 24B. It will be evident from the above that the three pusher elements of the present invention would lend themselves well to be molded using modular tooling. Thus any one of the three pusher elements of Figures 10 25A through 25C can be molded by inserting in the mold the correct two inserts from a set of four, thus reducing tooling costs. Modifications may be made in the invention without departing from the spirit of it.