Abstract:
Disclosed, is a drive ( 101 ) for a sedimentation tank ( 1000 ) comprising a main ring gear ( 160 ) operatively connected to a cage ( 150 ) via a web portion ( 152 ). A bearing transfer ring ( 170 ) is provided to the web portion ( 152 ) such that a gap ( 172 ) is provided between the bearing transfer ring ( 170 ) and the main ring gear ( 160 ). The bearing transfer ring ( 170 ) is connected to a first bearing race ( 144 ) which communicates with a second bearing race ( 142 ) that is fastened to a base portion ( 136 ) of the drive ( 101 ). Torque (T) is delivered to the cage ( 150 ) to turn a rake assembly ( 1002 ). The gap ( 172 ) provides clearance for deflections, distortions, or deformations of the main ring gear ( 160 ) caused by bending stresses (B) in the main ring gear ( 160 ) may. The bearing transfer ring ( 170 ) absorbs stresses imparted to the main ring gear ( 160 ) and prevents fasteners ( 188 ) connected to stiff bearing races ( 144 ) from shearing. Also disclosed is a retrofit kit for a sedimentation tank drive, a sedimentation tank ( 1000 ) having a drive ( 101 ) according to the above description, and a method of thickening/clarifying slurry ( 1008 ) utilizing a drive ( 101 ) according to the above description.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to liquid/solid separation equipment used in the industrial, municipal, waste, tailings, chemical, and minerals processing technologies, and more particularly to mechanical drive means for sedimentation tanks used for thickening and clarifying slurry, and methods thereof. 
     Slurry  1008  entering a sedimentation tank  1000  typically comprises particles (solid sediments) which are suspended within a liquid fraction. The sedimentation tank  1000  serves to thicken or clarify the slurry  1008 . In some instances, the sedimentation tank  1000  may agglomerate the suspended particles using flocculent, thereby allowing the sediments to settle to the bottom  1006  of the tank and form sludge. The sludge is driven to a central lower outlet  1010  in the tank using a rotating rake assembly  1002 . Typically, a centrally-located drive having one or more motors turns the rake assembly  1002 . The drive may be mounted to a center pillar  1012 , or may otherwise be mounted to a bridge  1004  spanning a radius or entire diameter of the sedimentation tank  1000 . 
     Conventional drive designs are limited in the amount of torque that they can handle. Accordingly, if too much sludge builds up at the bottom  1006  of a sedimentation tank  1000 , resistance to the rake assembly  1002  increases, and can place large bending stresses on the main ring gear  60  of the drive  1 . 
     OBJECTS OF THE INVENTION 
     It is, therefore, an object of the invention to provide an improved sedimentation tank drive capable of delivering high torques while still maximizing service life and reducing maintenance intervals. 
     It is yet another object of the invention to reduce or completely eliminate bolt breakage at high torque levels in sedimentation tank drives. 
     These and other objects of the invention will be apparent from the drawings and description herein. Although every object of the invention is believed to be attained by at least one embodiment of the invention, there is not necessarily any one embodiment of the invention that achieves all of the objects of the invention. 
     SUMMARY OF THE INVENTION 
     A drive for a sedimentation tank comprises a main ring gear operatively connected to a cage or a shaft when mounted to a bridge via a web portion. A bearing transfer ring is provided to the web portion. A gap is provided between the bearing transfer ring and the main ring gear. The bearing transfer ring is connected to a first bearing race. In some embodiments, the first bearing race may be in operable communication with a second bearing race that is mounted to a base portion of the drive. In some embodiments, the main ring gear may comprise a mating portion which abuts a complimentary mating portion of a spacer. In some embodiments, a spacer may be provided on the web portion and positioned between a portion of the main ring gear and a portion of the bearing transfer ring. The spacer may serve to maintain an upper portion of the gap between the main ring gear and the bearing transfer ring during deflection, distortion, or deformation of the main ring gear. In some embodiments, the first bearing race may comprise a mating portion which abuts a complimentary mating portion provided on the bearing transfer ring. In some embodiments, a mating portion of the main ring gear may abut a mating portion of the first bearing race. In some embodiments, a spacer may be provided on the first bearing race and positioned between a portion of the main ring gear and a portion of the bearing transfer ring, in order to maintain a lower portion of the gap between the main ring gear and the bearing transfer ring during deflection, distortion, or deformation of the main ring gear. In some embodiments, the web portion may comprise a first set of apertures configured to receive fasteners which connect the bearing transfer ring to the web portion. In some embodiments, the web portion may comprise a second set of apertures configured to receive fasteners which connect the main ring gear to the web portion. In some embodiments, the first bearing race may comprise a set of apertures configured to receive fasteners which connect the first bearing race to the bearing transfer ring. In some embodiments, a second bearing race operatively communicating with the first bearing race may comprise a set of apertures configured to receive fasteners which connect the second bearing race to a base portion of the drive. 
     A method of thickening/clarifying slurry is also disclosed. The method comprises providing a drive which is operatively connected to a rake assembly via a cage; wherein the drive comprises a main ring gear operatively connected to the cage via a web portion. A bearing transfer ring is provided to the web portion such that a gap is formed between the bearing transfer ring and the main ring gear. The bearing transfer ring is connected to a first bearing race. The method further includes the steps of providing power to the drive thereby subjecting the main ring gear to torque and bending stresses; transferring an amount of said torque to the cage in order to move the rake assembly connected thereto; and transferring an amount of said bending stresses to the bearing transfer ring and the first bearing race during deflection, distortion, or deformation of the main ring gear. 
     A retrofit kit for modifying an existing sedimentation tank drive is also disclosed. The kit comprises a bearing transfer ring which is configured to be operatively connected to a web portion extending between a main ring gear and a cage. The bearing transfer ring is further configured to be operatively connected to a first bearing race (e.g., via one or more fasteners). In use, a gap (e.g., which may be any clearance greater than zero or press fit, for instance, 0.005 inches) is formed between the bearing transfer ring and the main ring gear, eliminating direct connection between the main ring gear and the first bearing race. Moreover, the bearing transfer ring is configured to transfer bending stresses from the main ring gear through the web portion and to the first bearing race during deflection, distortion, or deformation of the main ring gear. 
     A sedimentation tank is also disclosed. The sedimentation tank comprises a rake assembly driven by a drive, which is operatively connected to the rake assembly via a cage. The drive comprises a main ring gear which is operatively connected to the cage via a web portion. A bearing transfer ring is provided to the web portion of the drive, such that a gap is formed between the bearing transfer ring and the main ring gear. The bearing transfer ring is connected to a first bearing race. The drive may be mounted to a center pillar, or may otherwise be mounted to a bridge which spans a radius or entire diameter of the sedimentation tank. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a cross sectional view of a conventional sedimentation tank drive; 
         FIG. 2  is an isometric view of a sedimentation tank drive according to some embodiments; 
         FIG. 3  is a partial view of the sedimentation tank drive shown in  FIG. 2 ; 
         FIG. 4  is an even more partial view of the sedimentation tank drive shown in  FIG. 2 ; 
         FIG. 5  is a detailed cross-sectional view of  FIG. 3 ; 
         FIG. 6  is a detailed view showing the particulars of  FIG. 5  and more clearly showing the function of a bearing transfer ring according to some embodiments; 
         FIG. 7  is an isometric cross sectional view of certain components of a drive according to some embodiments; 
         FIG. 8  is a schematic view of a sedimentation tank which may practice the invention according to some embodiments; 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows a cross sectional view of a prior sedimentation tank drive  1 . The drive  1  comprises several pinions  10  which drive a main ring gear  60  at a mesh zone  61 . Each pinion  10  comprises an upper first spindle portion  12 , a lower second spindle portion  14 , and a torque surface  16  to which powered rotational input means (such as an electric motor having a reducer) can apply a rotational input to the pinion  10 . The pinion rests in an upper first bearing  20  and a lower second bearing  22 . A bearing block  32  seats/houses the first bearing  20 , and a base portion  36  of the drive  1  seats/houses the second bearing  22 . 
     A cover plate  30  provides an upper mounting surface to the drive  1 . Reducer mounts  31  may be provided to the drive  1  to facilitate mounting of the powered rotational input means. A reducer abutment plate  93  may be used to limit the stopping depth of the reducer (not shown) and align the torque surface  16  with complimentary components (e.g., planet gears in the reducer). The reducer mounts  31  comprise a lower mounting portion  34 . An upper seat portion  33  supports the cover plate  30 . A web portion  52  which connects the main ring gear  60  to a cage  50  rotates with respect to the base portion  36  of the drive  1 . The main ring gear  60  is directly bolted, via one or more fasteners  84 , to an outer race  44  of a third bearing  40 . The outer race  44  communicates with an inner race  42 , wherein a plurality of bearing rollers  49  are disposed between the inner  42  and outer  44  races. 
     The base portion  36  of the drive  1  is connected to a stationary center pillar (such as the center pillar  1012  shown in  FIG. 8 ). The base portion  36  further comprises an upwardly extending cylindrical outer rim portion  38  having a first seal lip  37  thereon. As the main ring gear  60 , web portion  52 , and cage  50  rotate as a unit, the first seal lip  37  prevents dirt and liquids from migrating into the drive  1 . The cover plate  30  extends past the web portion  52  and comprises an overhanging annular seal ring  35  that extends downwardly from the cover plate  30 . A second seal lip  57  extends upwardly from the cage  50  making contact with a lower portion of the cover plate  30 , thereby preventing dirt and liquids from migrating into the drive  1 . 
     A rake mount  51  is provided to the cage  50  for mounting a rake assembly such as the rake assembly  1002  shown in  FIG. 8 . Fasteners  84  mount the outer race  44  of the third bearing  40  directly to the main ring gear  60 . Moreover, fasteners  82  mount the main ring gear  60  directly to the web portion  52 . When the main ring gear  60  is loaded with high stresses by pinions  10  driven at high torques, its thin, annular shape makes it tend to warp or twist within the drive  1 . Conversely, such warping and twisting due to high torsional stresses is resisted by the outer race  44  of the third bearing  40 , since the third bearing  40  is specifically designed to resist such distortion. Accordingly, fasteners  84  holding the stiff outer race  44  to the somewhat flexible main ring gear  60  end up succumbing to failure at the interface between the gear  60  and the outer race  44 . Failure(s) may be especially prevalent during “lockups” of reducers or other unforeseen control issues. 
       FIG. 2  shows an isometric view of a drive  101  according to some embodiments of the invention. A base portion  136  is mounted to a stationary center pillar  1012 . An outer cage  150  rotates with respect to both the base portion  136  and inner portion  139  of said base portion  136 . The cage  150  has a plurality of rake mounts  151  provided thereon, to which a rake assembly  1002  such as the one shown in  FIG. 8  is affixed. A plurality of motors  153  each having its own reducer  154  are provided around the drive  101 . Each of the reducers  154  join to a cover plate  130  of the drive  101  via a reducer mount  131  extending upwardly from the cover plate  130 . 
       FIG. 3  shows a partial view of  FIG. 2 , with the motors  153  and reducers removed  154  for clarity. As shown, a pinion  110  is disposed within each reducer mount  131 , and then an upper pinion contact adjuster plate  134  is disposed thereover. A plurality of fasteners  189  secure the upper pinion contact adjuster plate  134  to the rest of the base portion  136 , and keep the pinion  110  disposed within the drive  101 . 
       FIG. 4  shows an even more partial view of the sedimentation drive in  FIG. 2 . As shown, each reducer mount  131  may be provided in a floating configuration and having an elongated torque arm  187  provided thereon. The torque arm  187  may be attached to the reducer mount via a weld  183  as shown in the exemplary embodiment, or the torque arm  187  may otherwise be mounted to or form a portion of reducer mount  131  using fasteners or other means. The torque arm  187  generally allows constant contact adjustment to occur between a pinion  110  and the main ring gear  160  to provide optimal meshing. A distal end of the torque arm  187  may extend into an adjacent space, opening, or groove  199  defined between a first holding block  191  and a second holding block  192 . Each torque arm  187  may be secured in an up-and-down direction, via the cover plate  130 . The cover plate  130  rests against and secures to the first retainer mount  197  and the second retainer mount  198 , thereby capturing the torque arm  187 . During use, torque arm  187  allows small axial misalignments and radial displacements as if the main ring gear  160  during deflection, distortion, or deformation of said main ring gear  160 . 
       FIG. 5  is a cross-sectional view of the drive  101  of  FIG. 3 . The drive  101  comprises a pinion  110  which engages the teeth  166  of and drives a main ring gear  160  at a mesh zone  161 . The pinion  110  may comprise an upper first spindle portion  112 , a lower second spindle portion  114 , and a torque surface  116  to which powered rotational input means (such as an electric motor  153  having a reducer  154 ) can apply a rotational input to the pinion  110 . The pinion  110  rests in an upper first bearing  120  and a lower second bearing  122 . A first packing washer  113  keeps the upper first bearing  120  in proper position and keeps rollers within the first bearing  120  from becoming unseated. A second packing washer  117  keeps the lower second bearing  122  in proper position and keeps rollers within the second bearing  122  from becoming unseated. An upper eccentric bearing block  132  seats the first bearing  120 , and a lower eccentric bearing block  133  which is seated within the base portion  136  of the drive  101  houses the second bearing  122 . The upper  132  and lower  133  eccentric bearing blocks each have offset bores which house the upper  120  and lower  122  bearings. In the particular example shown, the bores are offset approximately 0.015 inches; however, other offsets are anticipated. The blocks  132 ,  133 , therefore, may be independently rotated in opposite directions, in order to offset an axis angle  175  or position of the pinion  110 . Moreover, the pinion  110  may be positioned closer to or farther away from main ring gear  160  by rotating the upper and lower bearing blocks  132 ,  133  in the same direction, simultaneously. Further holding the pinion to the drive  101  is a lower pinion contact adjuster plate  190  which is secured to the base portion  136  (below the lower second spindle portion  114 ) via a plurality of fasteners  185 . 
     As shown in  FIGS. 3-7 , a cover plate  130  provides an upper mounting surface to the drive  101 . One or more reducer mounts  131  may be provided to the drive  101  to facilitate mounting of the powered rotation input means, for instance, a motor  153  with planetary reducer  154 . A reducer abutment plate  193  may be used to limit the stopping depth of the reducer  154  and align the torque surface  116  with complimentary components (e.g., planet gears in the reducer  154 ). Reducer mounts  131  are connected to the base portion  136  via the pinion contact adjuster plate  134  which captures the mount  131  by fasteners  189 . Also captured by pinion contact adjuster plate  134  is the upper eccentric bearing block  132 , the upper first bearing  120 , and the first packing washer  113 . A web portion  152  which connects the main ring gear  160  to a cage  150  rotates with respect to the base portion  136  of the drive  101 . The main ring gear  160  is operatively connected to the web portion  152 , e.g., via a plurality of fasteners  182  which are inserted through apertures  196  in the web portion  152  and fastened to the main ring gear  160 . A bearing transfer ring  170  is also operatively connected to the web portion  152 , e.g., via a plurality of fasteners  186  which are inserted through apertures  195  in the web portion  152  and fastened to the bearing transfer ring  170 . The bearing transfer ring  170  is also operatively connected to an outer race  144  of a third bearing  140 , e.g., via a plurality of fasteners  188  which are inserted through apertures  141  in the outer race  144  and fastened to the bearing transfer ring  170 . The outer race  144  communicates with an inner race  142 , wherein a plurality of bearing rollers  149  are disposed between the inner  142  and outer  144  races. While not shown, the respective radial locations of inner  142  and outer  144  races may be reversed without necessarily departing from the scope of the invention. Accordingly, rollers  149  in the third bearing  140  may instead be located radially outwardly of the bearing transfer ring  170 . 
     The base portion  136  of the drive  101  is connected to a stationary center pillar  1012  as will be appreciated by  FIG. 8  by one or more fasteners  181  through holes  165 . The center pillar  1012  does not move and generally serves to support a bridge  1004  and the torque loads generated by the drive. The base portion  136  further comprises an upwardly extending cylindrical outer rim portion  138  having a first seal lip  137  thereon. As the main ring gear  160 , the web portion  152 , the bearing transfer ring  170 , and the cage  150  rotate as a unit, the first seal lip  137  prevents dirt and liquids from migrating into the drive  101 . The cover plate  130  extends past the web portion  152  and comprises an overhanging annular seal ring  135  that extends downwardly from the cover plate  130 . A second seal lip  157  extends upwardly from the web portion  152 , making contact with at least one of a lower portion of the cover plate  130  and an inner portion of the overhanging annular seal ring  135 , thereby preventing dirt and liquids from migrating into the drive  101 . 
     In some instances, fasteners  182  may mount the main ring gear  160  directly or indirectly to the web portion  152 . Similarly, fasteners  186  may mount the bearing transfer ring  170  directly or indirectly to the web portion  152 . Furthermore, fasteners  184  may mount the outer race  144  of the third bearing  140  directly or indirectly to the bearing transfer ring  170 . Lastly, fasteners  184  may mount the inner race  142  directly or indirectly to the base portion  136 . A rake mount  151  may be provided to the cage  150  for mounting a rake assembly  1002  such as the one shown in  FIG. 8 . A gap  172  is provided between the main ring gear  160  and the bearing transfer ring  170  so that when the main ring gear  160  is loaded with high bending stresses B, its thin, annular shape can warp or twist within the drive  101  without imparting much fatigue or shear to fasteners  188  associated with the outer race  144 . Accordingly, rather than fasteners  84  holding the stiff outer race  44  directly to the somewhat flexible main ring gear  60  as in the prior art, fasteners  188  hold the stiff outer race  144  to the bearing transfer ring  170 . In this way, torque T may be delivered to the rake assembly  1002  via the web portion  152 , and bending stresses B (e.g., tensile, compressive, shear, torsional) experienced by the main ring gear  160  and cage  150  may be transferred through the web portion  152  and bearing transfer ring  170 , and then to the outer race  144  of the third bearing  140 . Gap  172  may be one of any clearance which is greater than zero or greater than a press fit interface. For instance, in some non-limiting examples, gap  172  may be approximately 0.005 inches. In other non-limiting examples, gap  172  may be several millimeters. In yet even other non-limiting examples, gap  172  may comprise a clearance between the main ring gear  160  and outer race  144  which provides a very snug clearance fit. In yet even other non-limiting examples, gap  172  may comprise a clearance between the main ring gear  160  and outer race  144  which provides a very loose clearance fit. The gap  172  may also simply be a result of component configuration and/or tolerances within the drive  101 . 
     Turning now to  FIG. 6 , a cross-section of drive  101  is shown. Main ring gear  160  may comprise a first mating portion  162  and a second mating portion  164  which serve to pilot/align the main ring gear  160  with respect to a spacer  155  provided to the web portion  152  and a spacer  147  provided to the outer race  144  of the third bearing  140 . The spacers  147 ,  155  may be provided in the form of one or more protrusions or bosses (e.g., integral pins) circumferentially spaced from each other, an undulating or splined matching surface, or a continuous solid annular ring projection as shown. Spacer  155  may comprise a seventh mating portion  158  which is complimentary in shape and/or fit with the first mating portion  162  of the main ring gear  160 . Spacer  147  may comprise a sixth mating portion  146  which is complimentary in shape and/or fit with the second mating portion  164  of the main ring gear  160 . In the particular non-limiting embodiment shown, the first  162  and second  164  mating portions of the main ring gear  160  each comprise an annular circumferential shelf. In other embodiments, however, the first  162  and second  164  mating portions of the main ring gear  160  may alternatively comprise annular grooves, lips, undercuts, castellations, radially extending projections (e.g., pins), or other imaginable features which would serve as complimentary abutment means to bear against, fit within, or otherwise mate with the mating portions  146 ,  158  of spacers  147 ,  155 . 
     In a similar fashion to the main ring gear  160 , the bearing transfer ring  170  also comprises a third mating portion  174  and a fourth mating portion  176  which serve to pilot/align the bearing transfer ring  170  with respect to the spacer  155  provided to the web portion  152  and the spacer  147  provided to the outer race  144  of the third bearing  140 . Spacer  155  may comprise an eighth mating portion  159  which is complimentary in shape and/or fit with the third mating portion  174  of the bearing transfer ring  170 . Spacer  147  may comprise a fifth mating portion  145  which is complimentary in shape and/or fit with the fourth mating portion  176  of the bearing transfer ring  170 . In the particular non-limiting embodiment shown, the third  174  and fourth  176  mating portions of the bearing transfer ring  170  each comprise an annular circumferential shelf. In other embodiments, however, the first  162  and second  164  mating portions of the main ring gear  160  may alternatively comprise annular grooves, lips, undercuts, radially extending projections (e.g., pins), or other features which would serve as complimentary abutment means to bear against, fit within, or otherwise mate with the mating portions  145 ,  159  of spacers  147 ,  155 . 
       FIG. 7  is a partially-exploded isometric cross-sectional view better illustrating select components of the drive  101  shown in  FIGS. 2-5 , and having some components of the drive  101  not shown for clarity. As shown, the inner race  142  of the third bearing  140  may comprise a set of apertures  148  which each receive a fastener  184  that is secured to a base portion  136  of the drive  101 . Clearance between the main ring gear  160  and the inner race  142  may provide ample room for securement of the fasteners  184 , including the head of each fastener, without physical interference from the rotating main ring gear  160 . While not shown, fasteners  184  securing the inner race  142  of the third bearing  140  to the base portion  136  of the drive  101  may be countersunk within the inner race  142  or provided with low-profile geometries in order to provide additional clearance between the main ring gear  160  and the inner race  142 . Fasteners  188  securing the outer race  144  of the third bearing  140  to the bearing transfer ring  170  are also afforded clearance from the base portion  136  of the drive  101  in order to prevent binding during rotation of the cage  150  with respect to the base portion  136 . 
       FIG. 8  is a schematic view of an apparatus which may practice the invention according to various embodiments. A sedimentation tank  1000 , which might comprise, for instance, a thickener/clarifier device comprises a tank bottom  1006 , a feed for introducing slurry  1008 , and a central lower outlet  1010  adapted for removing settled solids which precipitate over time. A rake assembly  1002 , which is connected to the cage  150  of the drive  101 , rotates with respect to the tank bottom  1006  and “scoops” sediment towards the central lower outlet  1010 . A plurality of motors  153  having reducers  154  work to spin pinions  110  within the drive  101 . The pinions  110  in turn, rotate the main ring gear  160  within the drive  101 , which, in turn, provides the torque necessary to move the cage  150 , and the rake assembly  1002  attached to the cage  150 . The drive  101  may be mounted to a stationary center pillar  1012  that supports an access bridge  1004 , or a bridge (not shown) that extends entirely across the sedimentation tank  1000 . 
     A contractor or other entity may provide a sedimentation drive or install a sedimentation drive according to a process in whole, or in part, as shown and described. For instance, the contractor may receive a bid request for a project related to designing a sedimentation drive system, or the contractor may offer to design or provide such an apparatus or system for a client. The contractor may then provide, for example, any one or more of the devices or features thereof shown and/or described in the embodiments discussed above. The contractor may provide such devices by selling those devices or by offering to sell those devices. The contractor may provide various embodiments that are sized, shaped, and/or otherwise configured to meet the design criteria of a particular client or customer. The contractor may subcontract the fabrication, delivery, sale, or installation of a component or whole of the devices disclosed, or of other devices used to provide said devices. The contractor may also survey a site and design or designate one or more storage areas for stacking the material used to manufacture the devices. The contractor may also maintain, modify, replace, or upgrade the provided devices. The contractor may provide such maintenance or modifications by subcontracting such services or by directly providing those services or components needed for said maintenance or modifications, and in some cases, the contractor may modify an existing sedimentation drive, sedimentation tank, or other thickener/clarifier device with a “retrofit kit” to arrive at a modified drive or one or more components thereof which comprise one or more method steps, devices, or features of the designs discussed herein. 
     Although the invention has been described in terms of particular embodiments and applications, one of ordinary skill in the art, in light of this teaching, can generate additional embodiments and modifications without departing from the spirit of or exceeding the scope of the claimed invention. Accordingly, it is to be understood that the drawings and descriptions herein are proffered by way of example to facilitate comprehension of the invention and should not be construed to limit the scope thereof. 
     
       
         
               
             
               
               
             
           
               
                   
               
               
                 REFERENCE NUMERAL LIST 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 T 
                 Torque output to rake assembly 
               
               
                 B 
                 Bending stress 
               
               
                 1 
                 Drive 
               
               
                 10 
                 Pinion 
               
               
                 12 
                 First spindle portion 
               
               
                 14 
                 Second spindle portion 
               
               
                 16 
                 Torque surface 
               
               
                 20 
                 First bearing 
               
               
                 22 
                 Second bearing 
               
               
                 30 
                 Cover plate 
               
               
                 31 
                 Reducer mount 
               
               
                 32 
                 Bearing block 
               
               
                 33 
                 Upper seat portion 
               
               
                 34 
                 Lower mounting portion 
               
               
                 35 
                 Overhanging annular seal ring 
               
               
                 36 
                 Base portion 
               
               
                 37 
                 First seal lip 
               
               
                 38 
                 Outer rim portion 
               
               
                 39 
                 Inner portion 
               
               
                 40 
                 Third bearing 
               
               
                 42 
                 Third bearing inner race 
               
               
                 44 
                 Third bearing outer race 
               
               
                 49 
                 Third bearing roller 
               
               
                 50 
                 Cage or shaft 
               
               
                 51 
                 Rake mount 
               
               
                 52 
                 Web portion 
               
               
                 57 
                 Second seal lip 
               
               
                 60 
                 Main ring gear 
               
               
                 61 
                 Mesh zone 
               
               
                 82 
                 Fastener, web portion to main ring gear 
               
               
                 84 
                 Fastener, main ring gear to third bearing outer race 
               
               
                 93 
                 Reducer abutment plate 
               
               
                 101 
                 Drive 
               
               
                 110 
                 Pinion 
               
               
                 112 
                 First spindle portion 
               
               
                 113 
                 First packing washer 
               
               
                 114 
                 Second spindle portion 
               
               
                 116 
                 Torque surface 
               
               
                 117 
                 Second packing washer 
               
               
                 120 
                 First bearing 
               
               
                 122 
                 Second bearing 
               
               
                 130 
                 Cover plate 
               
               
                 131 
                 Reducer mount 
               
               
                 132 
                 Upper eccentric bearing block 
               
               
                 133 
                 Lower eccentric bearing block 
               
               
                 134 
                 Upper pinion contact adjuster plate 
               
               
                 135 
                 Overhanging annular seal ring 
               
               
                 136 
                 Base portion 
               
               
                 137 
                 First seal lip 
               
               
                 138 
                 Outer rim portion 
               
               
                 139 
                 Inner portion 
               
               
                 140 
                 Third bearing 
               
               
                 141 
                 Set of apertures 
               
               
                 142 
                 second or inner race of the third bearing 
               
               
                 144 
                 first or outer race of the third bearing 
               
               
                 145 
                 Fifth mating portion 
               
               
                 146 
                 Sixth mating portion 
               
               
                 147 
                 Spacer 
               
               
                 148 
                 Set of apertures 
               
               
                 149 
                 Third bearing roller 
               
               
                 150 
                 Cage or shaft 
               
               
                 151 
                 Rake mount 
               
               
                 152 
                 Web portion 
               
               
                 153 
                 Motor 
               
               
                 154 
                 Reducer 
               
               
                 155 
                 Spacer 
               
               
                 156 
                 Shelf 
               
               
                 157 
                 Second seal lip 
               
               
                 158 
                 Seventh mating portion 
               
               
                 159 
                 Eighth mating portion 
               
               
                 160 
                 Main ring gear 
               
               
                 161 
                 Mesh zone 
               
               
                 162 
                 First mating portion 
               
               
                 164 
                 Second mating portion 
               
               
                 165 
                 Holes 
               
               
                 166 
                 Teeth 
               
               
                 170 
                 Bearing transfer ring 
               
               
                 172 
                 Radial gap between main ring gear and bearing transfer ring 
               
               
                 174 
                 Third mating portion 
               
               
                 175 
                 Axis angle 
               
               
                 176 
                 Fourth mating portion 
               
               
                 181 
                 Fastener, base portion to column or bridge 
               
               
                 182 
                 Fastener, web portion to main ring gear 
               
               
                 183 
                 Weld 
               
               
                 184 
                 Fastener, third bearing inner race to base portion 
               
               
                 185 
                 Fastener, lower pinion contact adjuster plate 
               
               
                 186 
                 Fastener, web portion to bearing transfer ring 
               
               
                 187 
                 Torque arm 
               
               
                 188 
                 Fastener, bearing transfer ring to third bearing outer race 
               
               
                 189 
                 Fastener, upper pinion contact adjuster plate to base portion 
               
               
                 190 
                 Lower pinion contact adjuster plate 
               
               
                 191 
                 First holding block 
               
               
                 192 
                 Second holding block 
               
               
                 193 
                 Reducer abutment plate 
               
               
                 195 
                 First set of apertures 
               
               
                 196 
                 Second set of apertures 
               
               
                 197 
                 First retainer mount 
               
               
                 198 
                 Second retainer mount 
               
               
                 199 
                 Space/opening/groove 
               
               
                 1000 
                 Sedimentation tank/thickener/clarifier 
               
               
                 1002 
                 Rake assembly 
               
               
                 1004 
                 Bridge 
               
               
                 1006 
                 Tank bottom 
               
               
                 1008 
                 Slurry 
               
               
                 1010 
                 Central lower outlet 
               
               
                 1012 
                 Center pillar