Tracked running gear assembly in particular for small excavators

A tracked running gear assembly (1) for small excavators, comprising a frame (15) supporting:

• a drive wheel (2), a track tensioning wheel (3), and a plurality of load-bearing wheels (4), all of said wheels engaging along a part of their perimeter an endless crawler track (5) having an upper branch and a ground-contacting lower branch, wherein said load-bearing wheels (4) and said track tensioning wheel (3) each comprise an idle roller (6) maintained on a shaft (7) by two locking elements (8) mounted as an interference fit on the ends of said shaft (7);
• said idle roller (6) comprising a lubricant chamber (9) and being constructed of ferritic-pearlitic spheroidal graphite cast iron subjected to austempering heat treatment;
• said shaft (7) having an internally threaded (14) axial hole (12) at both ends for fixing the wheel (2, 3) on both sides to said frame (15) of said track running gear assembly (1), wherein at least one of said axial holes (12) extends to form a duct (16), said duct communicating with the interior of said lubricant chamber (9) when said roller (6) is mounted on said shaft (7) and is provided internally with a plug (17), said shaft (7) being constructed of a constructional carbon steel lightly alloyed with chromium and/or boron;
• each of said locking elements (8) comprising a seat (18) for a seal means (19), said seal means (19) positioned between the locking element (8) and the roller (6), said locking elements (8) being constructed of spheroidal graphite cast iron of prevalently ferritic matrix;
• said drive wheel (2) comprising a sprocket ring (26) removably fixable to the outside of an inner hub (27) and constructed of spheroidal ferritic-pearlitic cast iron subjected to austempering heat treatment.