Abstract:
A bearing block assembly includes a liner having a two piece ring of low friction material extending around the rockshaft and held in place by a bearing block. The rockshaft includes a radially projecting member interacting with the bearing block assembly to maintain the axial position of the rockshaft. The bearing liner includes a flange extending beyond the bearing block to contact the projecting member. The flange is seated in a groove at the side of the bearing block and lowers the coeffiecient of friction at the rockshaft/thrust surface interface.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates generally to bearing block assemblies for large rotating tubular members such as agricultural implement rockshafts and, more specifically, to wear insert structure with a thrust surface for such assemblies.  
       BACKGROUND OF THE INVENTION  
       [0002]     Round steel rockshafts of tubular or solid cross section are commonly utilized to control height on implement frames and disk gang attachments. Bearing block assemblies typically support the shaft from a frame, and a hydraulic cylinder rotates the rockshaft to raise and lower the frame or gang. The bearing block assemblies include a two-piece cast iron or welded steel bearing block which allows rotation about an axis but limit movement in the direction of the axis. As the rockshaft rotates, often under very heavy loading, wear occurs between the steel rockshaft and the metallic bearing block. Although the bearing blocks often include a grease fitting for lubrication to reduce the wear, the hostile operating environment results in contamination of the lubricant with dust and sand which accelerates the wear. To purge the contaminants from between the rockshaft and bearing block, frequent over-greasing is required to discharge the contaminants. This greasing process is often inconvenient because of the location of the assemblies in hard to reach areas and is time-consuming and messy.  
         [0003]     A further problem inherent with many bearing block assemblies for large applications such as agricultural implement lift systems is one of manufacturing tolerances of the shafts and of the cast iron or welded steel bearing blocks. A loose or sloppy fit between the mating parts resulting from the tolerances, combined with excessive wear that is commonly encountered in the hostile operating environment, can result in functional problems for the lift systems. Rotating rockshafts retained by bearing blocks have high wear points between the contact members. This wear requires maintenance at a prescribed interval to lubricate these joints to reduce the wear and maintain smooth operation.  
         [0004]     Some implements use a one piece plastic liner to reduce wear. However, the one piece liner is difficult to replace if worn or damaged. In commonly assigned U.S. Pat. No. 6,932,512, a two-piece wear insert is described for eliminating greasing and reducing friction between the rockshaft and bearing block. The two-piece liner is easier to replace than a one-piece liner. However, such a liner does not provide thrust protection to accommodate side loads on the rockshaft and reduce friction and noise generated from the side loads.  
       SUMMARY OF THE INVENTION  
       [0005]     It is therefore an object of the present invention to provide an improved bearing block structure for agricultural implement lift systems that overcomes most or all of the above mentioned problems. It is a further object to provide such a structure with a liner that is easy to replace and yet provides thrust load protection.  
         [0006]     It is another object of the invention to provide an improved bearing liner for an implement bearing block assembly. It is a further object to provide such a liner which is easier to replace and has improved thrust protection and noise reduction compared to most presently available bearing liners.  
         [0007]     A bearing block assembly for an implement lift system includes a liner having a two piece ring of low friction material extending around the rockshaft and held in place by a bearing block. The rockshaft includes a radially projecting member interacting with the bearing block assembly to maintain the axial position of the rockshaft. The bearing liner includes a flange seated in a side groove of the bearing block and extending beyond the bearing block to contact the projecting member. The flange and side groove along with a central liner rib and corresponding central bearing block groove locate and support the liner in the proper position. The flange lowers the coeffiecient of friction at the rockshaft/thrust surface interface. The liner design therefore not only reduces or eliminates maintenance brought about by rotational motion and load but also protects from thrust loading along the rockshaft axis. The low friction flange also reduces thrust load noise and provides smoother rockshaft action. The low coefficient of friction of the insert material maintains smooth, quiet rockshaft operation and addresses frictional wear problems in all planes of contact at the bearing interface. The liner can be replaced easily without need to dismantle the entire lift system  
         [0008]     These and other objects, features and advantages of the present invention will become apparent from the description below in view of the drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]      FIG. 1  is a front perspective view of a portion of an agricultural tillage or seeding implement having a lift system rockshaft with a bearing block assembly.  
         [0010]      FIG. 2  is an enlarged perspective view of the bearing block assembly of  FIG. 1 .  
         [0011]      FIG. 3  is a view similar to  FIG. 2  but with parts removed to better show the bearing block inserts. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0012]     Referring to  FIG. 1 , therein is shown a portion of an agricultural tillage or seeding implement  10  having a main frame  12  supported for forward movement by lift wheel assemblies  14  and  18 . A transversely extending rockshaft  20  of circular cross section is connected by bearing block assemblies  22  and bearing block connector structures  24  to a transverse main frame tube  12   t  of rectangular configuration. Cylinders  30  are connected to lift arms  34  and  38  of the wheel assemblies  14  and  18 , respectively, for rotating the rockshaft  20  about a transverse rockshaft axis  20   a  and rocking the wheel assemblies  14  and  18  generally in unison to raise and lower the main frame  12 .  
         [0013]     The bearing block assemblies  22  include a first or bottom portion or half section  40  ( FIG. 2 ) and a mating second or top portion or half section  42 . The bottom and top portions  40  and  42  are generally identical in construction and include arc-shaped semi-circular cavities  50  and  52  which, when the portions  40  and  42  are connected, define a circular opening having a diameter slightly larger than the diameter of the rockshaft  20 . A radially extended stepped area or flat  58  is located at each end of each of the semi-circular cavities  50  and  52  adjacent a bolt-receiving section  60  having a bolt-receiving bore  62 . When the half sections  40  and  42  are joined around the rockshaft  20 , the adjacent stepped areas  58  define an axially extending anti-rotation flange receiving area  64  at the joint. Each of the bearing block portions  40  and  42  includes a flat  66  centered between the bores  62 . The flat  66  on the portion adjacent a face of the main frame tube  12   t  is secured against the tube  12   t  by the bearing block connector structure  24 .  
         [0014]     The bearing block assemblies  22  include bearing block liners or wear inserts  70  which, as shown in  FIGS. 2 and 3 , are generally identical and have outer surfaces conforming to the shape of the semi-circular cavities  50  and  52 . The inserts  70  may be fabricated from ultra high molecular weight polyethylene, and when assembled in the cavities, define a low friction cylindrical cavity of diameter approximately equal to the diameter of the rockshaft  20  and providing a bearing and support surface for the rockshaft as the rockshaft rotates about the axis  20   a.    
         [0015]     The wear inserts  70  include a central rib  74  ( FIG. 3 ) and thrust flanges  76  located at the axially outermost ends of the inserts. The thrust flanges include axially outwardly facing flat wear surfaces  78  offset outwardly from the corresponding axial faces of the bearing block portions  40  and  42  and outwardly from the cavities  50  and  52 . Axially inward surfaces  80  of the thrust flanges  76  bear against the sides of the portions  40  and  42  at the cavity locations.  
         [0016]     Radially projecting anti-rotation flanges  84  extend between the opposite thrust flanges  76  at the ends of the inserts  70 . The flanges  84  are connected to and extend radially outwardly from the thrust flanges  76  and the central rib  74 . As best seen in  FIG. 3 , each pair of anti-rotation flanges  84  is received in the corresponding anti-rotation flange receiving area  64  at the joint to secure the inserts  70  in the cavities  50  and  52  and prevent rotation of the inserts relative to the bearing block assembly. The rib  74  and the flanges  76  strengthen the inserts and help secure the inserts against axial movement relative to the bearing blocks. A rounded or arc-shaped notch  90  is located in each anti-rotation flange  84  adjacent each end of the rib  74 . The notch  90  conforms to a rounded wall portion  94  adjacent the bolt-receiving bore  62  and also helps to locate and secure the inserts in the cavities.  
         [0017]     Referring to  FIG. 4 , the half section  40  (and similarly the half section  42 ) includes a central groove  104  conforming to and receiving the corresponding rib  74  of the insert  70 . The groove  104  helps locate and contain the insert  70  within the half section  40 . Semicircular flange receiving grooves  106  with outwardly directed recessed walls or faces  108  are formed in the opposite sides of the section  40 , and the flange  76  is partially received within the grooves with the inwardly directed face  80  abutting the face  108  for locating and supporting the flange  76 .  
         [0018]     The wear inserts  70  and the first and second bearing block portions  40  and  42  are assembled around the rockshaft  20 , and the connector structure  24  is tightened against the main frame tube  12   t  to secure the bearing block portions around the rockshaft and support the rockshaft from the frame  12 . As shown, the connector structure  24  includes a bolt  124  extending through each pair of aligned bores  62 . The bolts  124  extend upwardly adjacent opposite faces of the tube  12   t  and through apertures in an upper mounting plate  126 . Upper threaded ends of the bolts  124  receive nuts tightened against the mounting plate  126  to secure bearing block portions  40  and  42  together around the inserts  70  and to draw the flat  66  on the portion  42  tightly against the lower face of the main frame tube  12   t.    
         [0019]     To replace the wear inserts  70 , the operator simply loosens or removes the bolts  124  to open up the bearing block portions from around the rockshaft  124  sufficiently to remove the individual semi-circular wear inserts  70  from the cavities. New inserts  70  are then placed in the cavities  50  and  52 , and the bolts  124  are tightened to rotatably secure the rockshaft  20  in position on the frame  12 . Maintenance of the bearing structures therefore is relatively simple and does not require dismantling of the implement lift system.  
         [0020]     The rockshaft  20  includes thrust structure indicated at  130  extending radially outwardly from the circular cross-section of the rockshaft. The thrust structure  130  is located adjacent the bearing block sections  40  and  42  and includes an axially inwardly facing thrust surface  136  which, when the bearing block sections are assembled around the rockshaft  20 , abuts or is closely adjacent the outwardly facing flat wear surface  78  on the thrust flange  76  of the wear insert  70  ( FIG. 3 ). The grooves  106  of the bearing block portions  40  and  42  provide backing at the edge of the opening for thrust flanges  76 . The structure secures the rockshaft  20  against axial movement relative to the main frame tube  12   t , and the wear insert thrust flange  76  protects against metal-to-metal contact under thrust loading. The low coefficient of friction of the insert material maintains smooth, quiet rockshaft operation and addresses frictional wear problems in all planes of contact at the bearing interface to reduce or eliminate bearing maintenance requirements.  
         [0021]     Having described the preferred embodiment, it will become apparent that various modifications can be made without departing from the scope of the invention as defined in the accompanying claims.  
       Assignment  
       [0022]     The entire right, title and interest in and to this application and all subject matter disclosed and/or claimed therein, including any and all divisions, continuations, reissues, etc., thereof are, effective as of the date of execution of this application, assigned, transferred, sold and set over by the applicant(s) named herein to Deere &amp; Company, a Delaware corporation having offices at Moline, Ill. 61265, U.S.A., together with all rights to file, and to claim priorities in connection with, corresponding patent applications in any and all foreign countries in the name of Deere &amp; Company or otherwise.