Abstract:
A wear shoe for mounting to a flight of a sludge collector. The wear shoe snaps into a surface of the flight at a desired location and is held in place with no additional fasteners or hardware. The wear shoe is able to be utilized with any channel-type flight configuration.

Description:
FIELD OF THE INVENTION 
     The invention relates to a sludge collector for treating wastewater, and more particularly, to a wear shoe for use with the flights of a sludge collector. 
     BACKGROUND OF THE INVENTION 
     Sludge collectors are commonly used in wastewater treatment plants to scrape settled sludge from the bottom of a settling tank and to skim floating waste off the surface of the wastewater. The settling tank is typically made of concrete with support tracks or rails in the bottom or floor of the tank and support tracks or rails on the side walls of the tank. The sludge collectors typically include a number of flights which are usually elongated members that extend the width of the tank. The flights are typically pultruded fiberglass in various profiles. 
     The flights are connected at each of their opposite ends to conveyor chains which carry the flights in a circuit along the bottom of the tank to perform the scraping operation and over the surface of the wastewater to perform the skimming operation. As the flights move along the bottom of the tank, the flights are supported by the rails extending along the tank bottom. As the flights move along the surface of the tank, the ends of the flights are supported by the rails mounted on the side walls of the tank. 
     The portions of the flights which engage the rails at the bottom and side walls of the tank are subject to wear. To minimize this wear, wear shoes are attached to the flights where the flights contact the rails to thereby protect the flights. Typically, wear shoes are attached to the flights with bolts or other fasteners. However, fasteners are subject to corrosion from exposure to the wastewater, making removal and replacement of worn shoes difficult. 
     Flights most often have a channel shape in cross-section. Wear shoes for this type of flight generally have a simple L-shape with two holes drilled in each leg of the wear shoe, allowing the wear shoe to be reversed after wear has occurred on one leg. In practice, however, most users simply discard the wear shoe without reversing it. This type of wear shoe is mechanically fastened with bolts and locknuts to the flights. In order to save on hardware, wear shoes can be bolted in-line with the chain attachment plates to utilize common mounting hardware. The hardware is often specified as  304  or  316  stainless steel due to corrosion. Therefore, the cost of flight assembly hardware can be very expensive and can become a significant portion of the overall product cost. 
     Other prior art wear shoes are available which eliminate the need for mechanical fasteners. These wear shoes allow for manual attachment of the wear shoes onto the flights. However, these prior art wear shoes are useable with only a single flight configuration, a flight having specialized ramps, flanges or protrusions. These designs also rely upon the flexing ability of the flight to allow the wear shoe to be installed. 
     SUMMARY OF THE INVENTION 
     The present invention includes a wear shoe that includes a flexible self-locking member rather than utilizing a flight with a cooperating profile, or rather than relying upon flexing of the flight. The wear shoe snaps into the flight and is able to be utilized with any currently available channel-type flight configuration. 
     The wear shoe design shown herein provides for the ability to mount the wear shoe to a channel type flight via simple drilling of at least one bore in the flight. For example, the prior art L-shaped wear shoes cannot be used with flights having a diamond configuration. However, by utilizing the wear shoe of the present invention which mounts on a surface of the flight, this problem is eliminated. This wear shoe design also allows the wear shoe to be located anywhere along the flight&#39;s length, eliminating the need to be lined up with the chain mounting attachment or any other hardware. 
     One wear shoe is described herein that is designed to contact the side rails of the settling tank and another wear show is described herein that is designed to contact the floor rails of the tank. 
     Other features and advantages of the invention will become apparent to those of ordinary skill in the art upon review of the following detailed description, claims, and drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of two wear shoes embodying the invention and a corresponding flight having a first configuration; 
     FIG. 2 is a view taken along line  2 — 2  of FIG. 1; 
     FIG. 3 is a perspective view of the wear shoes and a corresponding flight having a second configuration; 
     FIG. 4 is a view taken along line  4 — 4  of FIG. 3; 
     FIG. 5 is a perspective view of the wear shoes and a corresponding flight having a third configuration; 
     FIG. 6 is a view taken along line  6 — 6  of FIG. 5; 
     FIG. 7 is a perspective view of the wear shoes and a corresponding flight having a fourth configuration; 
     FIG. 8 is a view taken along line  8 — 8  of FIG. 7; 
     FIG. 9 is a partial sectional view of one embodiment of the wear shoe; and 
     FIG. 10 is a partial sectional view of another embodiment of the wear shoe. 
     Before one embodiment of the invention is explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings, there is shown in FIGS. 1 and 2 a pair of wear shoes  20  and  22  and a corresponding flight  24 . The flight  24  is of the C-shape configuration which includes a first leg  26 , a web  28 , a second leg  30  and a lip  32 . The lip  32  runs the length of the web  28  except for a portion  34  of the web  28  wherein the lip  32  is removed as will be described later. The lip  32  is designed to reduce the gap between the bottom of the tank and the flight to minimize solids build up on the floor of the tank. 
     The wear shoe  20  is designed to be mounted onto a surface of the flight  24 , such as the first leg  26 . It is the wear shoe  20  that contacts the rails on the side walls of the tank. With reference to FIGS. 1,  2  and  10 , the wear shoe  20  is a unitary piece and preferably molded of a plastic such as polyurethane or ultra-high molecular weight (UHMW) polyethylene. However, it should be noted that the wear shoe  20  could be fabricated of other materials. 
     The wear shoe  20  can be L-shaped in cross-section, as shown in FIG.  1  and including a central web  36  and a first leg  38 , or can be C-shaped cross-section, as shown in FIG. 3, and defined by a central web  36 , a first leg  38  and a second leg  40 . The web  36  has a first surface  42  and a second surface  44 . It is the surface  42  that is the wear surface which engages the side rails of the tank. A flange  46  extends outwardly from the first surface  42  and acts as a guide as the wear shoe  20  travels along the rails on the side of the tank. 
     As best shown in FIG. 10, a pair of resilient locking members  48  extend outwardly from the second surface  44 . Each locking member  48  preferably has a first resilient leg  50  and a second resilient leg  52 . A shoulder portion  56  extends outwardly from the second leg  52 . However, it should be noted that the locking members  48  could have various other configurations and still perform the same function. 
     Turning now to the other wear shoe  22 , this wear shoe  22  is designed to be mounted onto a surface of the flight  24 , such as the second leg  30 . It is the wear shoe  22  that is designed to contact the floor rails of the tank. With reference to FIGS. 1,  2  and  11 , the wear shoe  22  is a unitary piece and preferably molded of a plastic such as polyurethane or ultra-high molecular weight (UHMW) polyethylene. However, it should be noted that the wear shoe  22  could be fabricated of other materials. 
     The wear shoe  22  is generally L-shaped in cross-section and is defined by a central web  58  and a first leg  60 . The web  58  has a first surface  64  and a second surface  66 . It is the surface  64  that is the wear surface which engages the floor rails on the bottom of the tank. The leg  60  extends outwardly from the second surface  66 . A pair of resilient locking members  48 , as described above with respect to wear shoe  20 , extend outwardly from the second surface  66 . 
     It should be noted that the dimensions and materials from which the wear shoes  20  and  22  are fabricated may vary. For example, the length, depth and width of the wear shoe  20  which contacts the side rails of the tank may vary from the length, depth and width of the wear show  22  that contacts the floor rails of the tank. 
     Turning now to the installation of the wear shoe  20  and FIGS. 1 and 2, the wear shoe  20  does not utilize any mounting hardware separate from the wear shoe itself nor does the wear shoe  20  have to be mounted onto the flight  24  at a predetermined location. Rather, the wear shoe  20  can be mounted to the flight  24  at a location chosen by the user based upon a given application. 
     When a desired location for installation of the wear shoe  20  has been determined, two bores  68  are made through the first leg  26  of the flight  24 , such as by drilling. The diameter of the bores  68  corresponds to the dimensions of the locking members  48 , respectively as will become clear hereafter. The wear shoe  20  is then aligned with the bores  68  such that one locking member  48  is aligned with each bore  68  as is shown in FIG.  1 . In this alignment, the web  36  and the leg  26  are generally parallel and the leg  38  and the web  28  are generally parallel. 
     After alignment, the wear shoe  20  is manually lowered such that each locking member  48  enters a respective bore  68 . Further downward forcible movement temporarily deforms the legs  50  and  52  of each locking member  48  allowing the legs  50  and  52  to pass through the respective bore  68 . At the point where the shoulder portion  56  clears the bore  68 , the legs  50  and  52  snap back to their original orientation. In this position, the shoulder portion  56  of each locking member  48  prevents the wear shoe  20  from moving relative to the flight  24 , as is particularly shown in FIG.  2 . 
     The installation of the other wear shoe  22  is similar to that described above with respect to the wear shoe  20 . However, the wear shoe  22  needs to be mounted on the flight  24  in the portion  34  in which the lip  32  has been removed, such as by cutting. 
     Removal of the wear shoes  20  and  22  from the respective flight  24  can be accomplished either by prying thereby causing deformation of the locking members  48  until they clear the bore  68  or by removal of the locking members  48  from the surface  44  or  66  of the respective wear shoe  20  or  22 . 
     An advantage of the design of the wear shoes  20  and  22  is that they can be utilized with many different configurations of channel type flights as is shown in FIGS. 3-8 and described as follows. 
     Referring now to FIGS. 3 and 4, the wear shoes  20  and  22  and a corresponding flight  70  are shown. The flight  70  is of a Sigma Plus™ configuration which includes a first leg  72 , a second leg  74 , a non-planar web  76 , a third leg  78  and a lip  80 . The lip  80  runs the length of the web  76  except for a portion  82  of the web  76  where it is removed for installation of the wear shoe  22 . The wear shoe  20  is mounted onto a surface of the flight such as the second leg  74  and the wear shoe  22  is mounted onto a surface of the flight such as the third leg  78 . 
     Referring now to FIGS. 5 and 6, the wear shoes  20  and  22  and a corresponding flight  84  are shown. The flight  84  is of a diamond configuration which includes a first leg  86 , a second leg  88 , a non-planar web  90 , a third leg  92  and a lip  94 . The lip  94  runs the length of the web  90  except for a portion  96  of the web  90  where it is removed for installation of the wear shoe  22 . The wear shoe  20  is mounted onto a surface of the flight such as the second leg  88  and the wear shoe  22  is mounted onto a surface of the flight such as the third leg  92 . 
     Referring now to FIGS. 7 and 8, the wear shoes  20  and  22  and a corresponding flight  98  are shown. The flight  98  is of the Sigma™ configuration which includes a first leg  100 , a second leg  102 , a non-planar web  104 , a third leg  106 , a fourth leg  110  and a lip  112 . The lip  112  runs the length of the web  104  except for a portion  114  of the web  104  where it is removed for installation of the wear shoe  22 . The wear shoe  20  is mounted onto a surface of the flight such as the second leg  102  and the wear show  22  is mounted onto a surface of the flight such as the third leg  106 . 
     As can be appreciated from the description herein, the wear shoes  20  and  22  utilize themselves as both the flexing member, rather than the flight, and the self-locking member, rather than additional hardware or fasteners or specialized portions of the flight. With use of the wear shoes  20  and  22 , one does not have to rely upon the flexing of a flight or any specific configuration of the flight such as ramps, lead-ins, or projections. The wear shoes  20  and  22  of the present invention snap onto a surface of a flight. 
     The wear shoes  20  and  22  have the ability to be mounted to any channel-type flight configuration. This versatility is possible because the wear shoes  20  and  22  mount to a surface of a given flight simply by drilling holes into the surface at desired locations and snapping the wear shoes  20  or  22  into place. With the ability of the wear shoes  20  and  22  to be located any where along a flight&#39;s length, this eliminates the prior need to align with any chain mounting attachment and eliminates mounting hardware or additional fasteners.