Abstract:
An equalizer bar for a tracked vehicle is connected to the track roller frames via an arrangement comprising a pin which is swivel ably mounted to the equalizer bar and held rigidly by the track roller frame. The pin is positively held by the track roller frame, for example by channels in which the pin sits such that the side load is at least partially absorbed by the channel walls rather than the fasteners. The fasteners are located such that they experience minimal side load and aid a positive location of the pin in the channels.

Description:
TECHNICAL FIELD  
       [0001]     The disclosure generally relates to an arrangement for connecting two frames of a work machine and in particular, but not exclusively, to an arrangement for connecting a track roller frame to an equalizer bar of a track-type work machine.  
       BACKGROUND  
       [0002]     Track type work machines commonly use an equalizer bar between both the left and right hand tracks to allow a degree of flexibility in movement of the tracks relative to the main frame. The equalizer bar is pivot ably mounted to the main frame at a center line of both the main frame and the equalizer bar, whilst the two ends of the equalizer bar are connected with the left hand and right hand side track roller frames respectively. The connection between the equalizer bar and the track roller frame must allow a degree of movement between the equalizer bar and the track roller frame whilst being able to sustain severe loading. U.S. Pat. No. 4,324,303 and U.S. Pat. No. 4,018,295 describe solutions wherein an equalizer bar is mounted to a track roller frame bearing by a split cap arrangement.  
         [0003]     Disadvantages of such constructions may be that the joint is complex or not sufficiently durable, the pin is prone to seizure due to rust or deformation and assembly and disassembly may be relatively difficult.  
         [0004]     This disclosure is directed at overcoming one or more of the aforementioned disadvantages.  
       SUMMARY OF THE INVENTION  
       [0005]     The present disclosure reveals an embodiment of an arrangement for connecting a track roller frame to an equalizer bar of a work machine wherein the arrangement includes a pin connected with the equalizer bar and projecting therefrom. The pin has a surface portion with a passage therethrough and the track roller frame has a surface portion corresponding to the surface portion of the pin. The surface portion of the track roller frame has a passage extending therethrough, and a fastener extends through both the passages in the surface portions of the pin and the track roller frame.  
         [0006]     Another embodiment discloses a method of connecting a track roller frame to an equalizer bar of a work machine. The method includes the steps of providing the equalizer bar with a projecting pin having a longitudinal axis such that the longitudinal axis has three rotational degrees of freedom relative to the equalizer bar, positioning at least a portion of the pin in a recess located on the track roller frame, fastening the pin to the track roller frame by extending a fastener through the pin into a portion of the track roller frame.  
         [0007]     Other features and aspects of this disclosure will be apparent from the following description and the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]      FIG. 1  is a diagrammatic representation of an undercarriage arrangement for a work machine in accordance with an embodiment of the current disclosure.  
         [0009]      FIG. 2  is a drawing showing a more detailed view of a portion of the arrangement of  FIG. 1   
         [0010]      FIG. 3  is a more diagrammatic representation of a portion similar to that shown in  FIG. 2  but from a different perspective.  
         [0011]      FIG. 4  shows a representation of a portion of a track roller frame suitable for the arrangement of  FIG. 1 .  
     
    
     DETAILED DESCRIPTION  
       [0012]      FIG. 1  shows an embodiment of an undercarriage  12  for a tracked work machine  10 . The tracked work machine  10  may be propelled forward by any drive arrangement (not shown), which typically may be a pair of opposing drive shafts connected to the tracks adjacent to the rear end of the tracks (not shown). The undercarriage  12  may include a main frame  14 , which is connected to an equalizer bar  16  via a pivot arrangement  18 . The opposing first end  15  and second end  17  of the equalizer bar  16  are connected to a first track roller frame  20  and a second track roller frame  22  via connection arrangements  24  and  26  respectively. The pivot  18  enables the equalizer bar  16  to swivel relative to the main frame  14  to accommodate movement of the first and second track roller frames  20  and  22 , which may for example occur when the work machine  10  travels over uneven terrain. Both the first and second track roller frames  20  and  22  may be connected with the equalizer bar  16  in the same manner therefore only the connection between the equalizer bar and the first track roller frame  20  will be discussed in further detail, but it is to be understood that the same principle applies to the connection between the equalizer bar  16  and the second track roller frame  22 .  
         [0013]     Further referring to  FIGS. 2, 3  and  4 , the first end  15  has a passage  30 , which is machined to receive a bearing  32 . The bearing  32  is preferably a bearing that can accommodate a certain degree of misalignment or has self-aligning properties such as for example a spherical bearing or an elastomeric bearing, but any suitable bearing arrangement may be used. The bearing may be held in place in the passage  30  via any suitable means, e.g. press fitting or a circular spring and groove arrangement. The bearing  32  in this embodiment has an outer race  34  and an inner race  36  which are arranged such that the inner race  36  can rotate and swivel within the confines of the outer race  34  without being able to leave the confines of the outer race  34  during normal operation. The inner race  36  is in contact with a pin  40 , which extends through the bearing  32  so that its longitudinal axis  41  projects from at least one but preferably two sides of the equalizer bar. The first portion  42  and the second portion  44  are the portions of the pin  40  that project from the equalizer bar  16 . It follows that the pin  40  may rotate and swivel relative to the equalizer bar  16  such that the longitudinal axis  41  has the three rotational degrees of freedom relative to the equalizer bar  16 . The three rotational degrees of freedom are commonly known as pitch, yaw and roll. Pitch in this context may be described as the first and second portions  42  and  44  both moving in a generally vertical plane but in opposing directions as represented by the double arrow headed line  80 . Yaw is similar to pitch but takes place in generally horizontal directions as represented the double headed arrow line  82  and roll is where the pin  40  may roll around its longitudinal axis  41  as represented by line  84 . Of course the three rotational degrees of freedom may be combined or limited in any suitable manner if preferred.  
         [0014]     The pin  40  may be engaged with the inner race  36  in any suitable manner such as, for example, press fitting or swaging. A surface of the pin  40  may also form the inner race  36  so that the pin  40  and the bearing  32  form an integral unit. The first and second portions  42  and  44  may have generally convex surfaces  43  and  45  with flat portions  46  and  48  respectively. The flat portions  46  and  48  may be located at the top side of the pin  40  or adjacent thereto which will be explained in more detail below.  
         [0015]     The first portion  42  has a passage  50  extending through the whole of the diameter of the first portion  42  and intersecting the flat portion  46 . Similarly, the second portion  44  has a passage  52  extending through the whole of the diameter of the second portion  44  and intersecting the flat portion  48 .  
         [0016]     The track roller frame  20  is in this embodiment provided with two connection portions in the form of a first bracket  54  and a second bracket  56  which are cantilevered from the track roller frame  20 . The first and second brackets  54  and  56  have recesses in the form of first and second channels  58  and  60  respectively which are in line with each other and generally parallel to the track roller frame  20 . The first and second channels  58  and  60  have first and second surfaces  62  and  64  respectively which are in this embodiment generally concave or generally U-shaped thereby providing a first set of sidewalls  57  and  59  and a second set of sidewalls  61  and  63 .  
         [0017]     The first and second surfaces  62  and  64  match the generally convex surfaces  43  and  45  such that the pin  40  sits tightly in the first and second channels  58  and  60 . The first and second brackets  54  and  56  have passages  66  and  68  which may be threaded and which may be blind holes or extend through the whole of the first and second brackets  54  and  56 . When assembled, the pin  40  is positioned in the first and second channels  58  and  60  such that the passages  50  and  52  are aligned with the passages  66  and  68  respectively. A pair of fasteners  70  and  72  (fastener  70  is omitted from  FIG. 3 ) are then inserted through the passages  50  and  52  and into the passages  66  and  68 . In one embodiment the fasteners  70  and  72  are threaded setscrews that engage with threads located in the passages  66  and  68 , which may be blind holes, but the fasteners may also extend through the first and second brackets  54  and  56  and be fixed in position by a washer and nut arrangement. If the fasteners  70  and  72  are headed fasteners, the heads are preferably positioned such that they butt up against the flat portions  46  and  48  to facilitate and maintain a durable fixation.  
         [0018]     The pin  40  is positioned in the first and second channels  58  and  60  such that the first portion  42  is at least partially enclosed by the first set of sidewalls  57  and  59  and the surface  62 . The second portion  44  is correspondingly at least partially enclosed by the second set of sidewalls  61  and  63  and the surface  64 . There may be high lateral loading of the connection between the track roller frame  20  and the equalizer bar  16 , but the partial enclosing and tight fitting relationship of the pin  40  and the first and second channels  58  and  60  substantially prevents lateral movement of the pin  40  in the recesses formed by the first and second channels  58  and  60  and may significantly reduce the amount of lateral load that the fasteners  70  and  72  are exposed to.  
         [0019]     It is to be understood that the embodiment as described above can be varied in a variety of manners without departing from the scope of the claims. For example, in one embodiment the contacting surfaces of the pin  40  and first and second brackets  54  and  56  may be flat and the side load may be absorbed by a dowel arrangement, such as one where the dowels are part of the first and second bracket  54  and  56  whilst the pin  40  has matching tight fitting passages to engage the dowels. In another embodiment it may be preferred to utilize a rectangular or conical pin and channel configuration instead of a convex and concave configuration. It may also be preferred to arrange the portion on the track roller frame that engages the pin  40  such that it is a more integral part of the track roller frame rather than utilizing brackets  54  and  56 .  
       INDUSTRIAL APPLICABILITY  
       [0020]     The equalizer bar  16  and the track roller frame  20  may be relatively easily assembled and disassembled, due to the low number of parts and the positive positioning of the pin  40  in the channels  58  and  60 . The equalizer bar  16  is provided with the bearing  32  and the pin  40  after which the equalizer bar end  15  can be rested on the roller track frame such that the pin  40  is positioned in proximity to the channels  58  and  60 . Due to the bearing  32  being able to accommodate or adjust to misalignment, the pin  40  can be positioned such that the passages  52  and  68  and the passages  50  and  66  are aligned. Once aligned, the fasteners  70  and  72  which in this particular embodiment are threaded setscrews may be inserted into the passages  50  and  52  and the thread may engage with the thread in the passages  66  and  68 . Due to the relatively high forces that can be achieved by tightening of the fasteners  70  and  72 , the pin  40  may have a very tight fit in the passages  58  and  60 , because the tightening of the fasteners  70  and  72  will force the pin  40  into the passages  58  and  60 .  
         [0021]     During operation of the work machine  10  one of the functions of the equalizer bar  16  is to function like a tie-rod, preventing both the first and second track roller frames  20  and  22  from gaining an excessive toe-in or toe-out relative to the main frame. This results in the equalizer bar pushing and pulling both the first and second track roller frames  20  and  22 .  
         [0022]     Another function of the equalizer bar  16  is to enable the first and second track roller frames to move relative to one another to provide a more comfortable and safe travel over uneven terrain. For example, during travel the second track roller frame  22  may be forced upwards, typically by encountering an object in the path of travel. By being forced upwards, the second track roller frame  22  may induce a pivotal movement of the equalizer bar  16  relative to the main frame  14  via the pivot  18 . In turn, the equalizer bar  16  applies a force on the first track roller frame such that the position of the equalizer bar  16  relative to the first track roller frame  20  may change. The pin  40  is in a fixed relationship with the first and second brackets  54  and  56  and the inner race  36  of the bearing  32 . Due to the forces applied by the equalizer bar  16 , the inner race  36  will start to change position relative to the outer race  34 . The freedom of the inner race  36  to move relative to the outer race  34  allows to a certain extent a generally unrestricted movement of the equalizer bar  16  relative to the first track roller frame  20 .  
         [0023]     The pin  40  is held in position in the first and second brackets  54  and  56  by the pin being recessed in the channels  58  and  60  in combination with the fasteners  70  and  72 . Due to the pin being sunk into the recess, the first set of sidewalls  57 ,  59  and the second set of sidewalls  61 ,  63  prevent any sideways movement of the pin  40  relative to the brackets  54  and  56 . The fasteners  70  and  72  prevent the pin from being lifted out of the channels  58  and  60 . Without the channels taking the side load, the fasteners  70  and  72  would have to cope with the full side load which is likely to reduce the service life of the arrangement due to a high risk of the fasteners shearing.  
         [0024]     Although the preferred embodiments of this disclosure have been described herein, improvements and modifications may be incorporated without departing from the scope of the following claims.