R54459 Track Adjuster Assembly Fits Case 450C Long Track, 550 to s/n JAK0013968One New Aftermarket Replacement Complete Track Adjuster Assembly for Case Crawler Dozers This complete track adjuster assembly replaces OEM part number R54459 and fits the undercarriage system of Case crawler dozers. The track adjuster uses grease pressure and an internal recoil spring to maintain correct track tension, keeping the track chain aligned on the idler and rollers to reduce premature undercarriage wear. Each machine requires two assemblies