Abstract:
An apparatus and method for reducing vibrational effects of track chain assembly catenary hang is disclosed. A work machine includes a pair of track roller assemblies one positioned on each side of the work machine. The vibration reducing apparatus and method includes repositioning undercarriage components to vary the catenary hang from one side of the work machine to the other.

Description:
This application claims the benefit of U.S. Provisional Application No. 60/642,671, filed Jan. 10, 2005. 
    
    
     TECHNICAL FIELD 
     This invention relates generally to an undercarriage arrangement for a track laying work machine and more particularly to an undercarriage that reduces the vibrational effects of a catenary hang of the track chain assembly on opposite sides of a work machine. 
     BACKGROUND 
     Work machines are supported and propelled by various arrangements such as wheels, tracks and belts. These support arrangements to a large extent determine the quality of ride of the work machine, the performance of the work machine and the noise that the machine emits during operation. For example, work machines such as track laying work machines are supported and propelled by track chains. The motion of the track chains as they wrap are undercarriage components such as sprockets, idlers, etc. create a clanking and jarring type of motion. While doing fine working operations this motion can cause flaws in finishing operations. 
     Specifically, when a track type dozer is performing fine dozing operations, vibrations can occur that are caused by the mechanical components due to the nature of the machine as well as the terrain being traversed. These vibrations come from many sources such as the contact of the track chain to the sprocket, idlers, mid-rollers and carrier roller. Another source is the vibration is associated with the catenary hang of a track chain assembly on one side of the work machine being in phase with the track chain on the opposite side. 
     The present invention is directed to overcoming one or more of the problems as set forth above. 
     SUMMARY OF THE INVENTION 
     In one aspect of the present invention an undercarriage arrangement includes a first track roller and a second track roller assembly. The first and second track roller assemblies each have a roller frame, a drive sprocket, at least one idler assembly rotatably connected to the roller frame, a carrier roller rotatably connected to an upper portion of the roller frame and a track chain entrained around the drive sprocket, the at least one idler assembly, and the carrier roller. The track chain defines a catenary hang. The catenary hang of the first roller assembly being different than the catenary hang of the second roller assembly. 
     In yet another aspect of the present invention a method of reducing vibrational effects of a first and a second track roller assembly of a track type work machine includes providing the first track roller assembly with a roller frame, a drive sprocket, at least one idler rotatably connected to said roller frame, a carrier roller rotatably connected to an upper portion of said roller frame, a track chain entrained around the drive sprocket, the at least one idler, and the carrier roller, the track chain defining a catenary hang. Providing a second track roller assembly with a roller frame, a drive sprocket, at least one idle rotatably connected to said roller frame, a carrier roller rotatably connected to an upper portion of the roller frame, a track chain entrained around the drive sprocket, the at least one idler, and the carrier roller, the track chain defining a catenary hang. Varying the catenary hang of a one of a first roller assembly and a second roller assembly. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a plan view of a work machine embodying the present invention; 
         FIG. 2  is a side elevational view of a work machine showing multiple embodiments of the present invention; and 
         FIG. 3  is a side elevational view of a work machine showing additional embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to the drawings, specifically  FIG. 1 , a work machine  10  is shown, which is shown as being a track type dozer. However it is to be understood that the work machine could be a track type dozer, a track type loader, an excavator or any other work machine employing endless tracks as the means of supporting and propelling the machine. The work machine  10  includes a work implement  11  such as a dozer blade, an engine  12 , an operator&#39;s station  14  and a mainframe  16 . The mainframe  16  supports first and second track roller assemblies  18 , 20  one each being positioned on opposite sides of the main frame  16 . First and second roller assemblies  18 , 20  are substantially and functionally similar and, therefore, only one track roller assembly  18  will be described in detail with similar components of the second roller frame being referenced with like element numbers represented by a prime designation. 
     The first track roller assembly  18  includes a roller frame  22 . The roller frame  22  includes a drive sprocket  24  operably rotatably mounted at one end as shown in  FIG. 3  and operably rotatably mounted to the main frame as shown in  FIG. 2 . Rotatably mounted at the other end of the roller frame  22  is at least one idler assembly  26  as seen in both  FIGS. 2 and 3 . A plurality of supporting mid-rollers  28  are connected to a bottom portion  30  of the roller frame  22  and a carrier roller  32  is connected to an upper portion  34  of the roller frame  22 . A track chain assembly  40  is entrained around the drive sprocket  24 , the at least one idler assembly  26 , the supporting mid-rollers  28  and the carrier roller  32 . 
     The track chain assembly  40 , only a portion of which is shown, includes a plurality of subassemblies  42 . Each subassembly  40  includes a pin and bushing or cartridge assembly  44 , a pair of spaced apart or inner and outer links  46  and a track shoe  50  connected to the spaced apart track links  46 . A number of subassemblies  42  are mechanically coupled to adjacent subassemblies  42  so that when an appropriate number of these subassemblies  42  are connected together, the track chain assembly  40  is formed. The track chain assembly  40  has a predetermined length for a given application or track roller assembly  20 . 
     As shown in  FIGS. 2 and 3  each track chain assembly  40  defines a catenary hang  52 . The catenary hang  52  is the droop or sag of the track chain assembly  40  caused by the weight of the track chain assembly  40  and/or the tension provided by a track tension arrangement  54 . Track tension arrangement  54  may be any of a number of known arrangements such as hydraulic cylinders, grease cylinders, springs or the like. The catenary hang  52  occurs in the track chain assembly  40  from the drive sprocket  24  to the carrier roller  32  and from the carrier roller  32  to the at least one idler assembly  26 . Shown in both  FIGS. 2 and 3  the catenary hang  52  is the difference between the theoretically perfectly straight track chain assembly  40  and the actual sag designated by the track chain assembly  40  shown in phantom. 
     Several embodiments of a vibration reducing apparatus  56  are illustrated in  FIGS. 2 and 3 . Specifically, the vibration reducing apparatus  56  in general is created by varying the catenary hang  52  of the first track roller assembly  18  from the catenary hang  52 ′ of and the second track roller assembly  20 , which can be obtained by a variety of different means and methods. 
     One embodiment shown in  FIG. 2  is to move the carrier roller  32 ′ of the second roller assembly  20  to a position above or below the position of the carrier roller  32  of the first roller assembly  18 , the elevated position of carrier roller  32 ′ being shown in  FIG. 2 . By raising carrier roller  32 ′ the catenary hang  52 ′ for the second roller assembly  20  would be less than the catenary hang  52  of the first roller assembly  18 . Lowering carrier roller  32 ′ would cause a greater amount of catenary hang  52 ′ for the second roller assembly  20 . Another embodiment would be to move the at least one idler assembly  32 ′ of the second roller assembly  20  either forward or rearward of the at least one idler assembly  32  of the first roller assembly  18  by an exaggerated distance designated by “L” seen in  FIG. 2 . To achieve the movement of the at least one idler assembly  26 ′ the distance “L” the force exerted by tension arrangement  54 ′ could be increase or decreased by a predetermined amount so as to change the length of the track chain assembly  40 ′ supported between the carrier roller  32 ′ and the at least one idler assembly  26 ′. Thus varying the catenary hang  52 ,  52 ′ of the track chain assembly  40 ,  40 ′ between the first and second track roller assembly  18 , 20 . Movement of the idler assembly  26 ′ could alternately be achieved by lengthening or shortening the track roller frame  22 ′ by the distance “L”. Additionally, an extra subassembly  42 ′ could be added to or removed from the track chain assembly  40 ′ thus allow the at least one idler assembly  26 ′ to move forward or rearward by distance “L”. 
       FIG. 3  details further embodiments of the vibration reducing apparatus  56 . In this embodiment the carrier roller  32 ′ of the second roller assembly  20  would be moved either forward or rearward of the carrier roller  32  of the first roller assembly  18 . Thus changing the length of the track chain assembly  42 ′ supported between the drive sprocket  24 ′ and the carrier roller  32 ′ and the length of the track chain  42 ′ supported between the carrier roller  32 ′ and the at least one idler assembly  26 ′. Another embodiment shown in  FIG. 3  would move the centerline of the at least one idler assembly  26 ,  26 ′ upward a generally vertical distance designated by “H”. This would change the catenary hang  52 ,  52 ′ changing the support point from the carrier roller  32 ,  32 ′ and the at least one idler assembly  26 ,  26 ′. This could be achieved by physically moving the mounting location for the at least one idler assembly  26 ,  26 ′ to a different location or by increasing or decreasing the diameter of the at least one idler assembly  26 ,  26 ′. Conversely, the diameter of either of the drive sprockets  24 ,  24 ′ could be varied and provide a similar effect. 
     INDUSTRIAL APPLICABILITY 
     During operation of the work machine  10  if the catenary hang  52 ,  52 ′ of the track chain assembly  40 ,  40 ′ are identical vibrations occur due to the motion of the catenary hang  52 ,  52 ′ of the track chain assembly  40 ,  40 ′ moving in phase with one another. With the catenary movement being in phase causes vibrations that are additive in effect and causes the work implement  11  to bounce. The bounce of work implement  11  causes ripples or scallops in the terrain being worked while performing fine dozing operations. 
     By changing the catenary hang  52 , 52 ′ on either the first or second roller assembly  18 , 20  by any of the embodiments described above changes either the length of track chain assembly supported between the drive sprocket  24 ,  24 ′ and the carrier roller  32 ,  32 ′ and the length supported between the carrier roller  32 ,  32 ′ and the at least one idler assembly  26 ,  26 ′ . With the catenary hang  52 , 52 ′ being different between the first roller assembly  18  and the second roller assembly  20  the catenary movement of the track chain assembly  40 ,  40 ′ is placed out of phase with one another. Having the track chain assemblies  40 ,  40 ′ out of phase causes a canceling effect in the catenary movement of the track chain assemblies  40 ,  40 ′ between the first and second track roller assemblies improving the fine dozing effectiveness of the work machine  10 . 
     Other aspects, objects and advantages of this invention can be obtained from a study of the drawings, the disclosure and the appended claims.