CAT 322C hub reduction gear CAT 322C hub reduction gear The presented toothed ring is used in the upper row of satellites in CAT excavator reduction gears. It is used in models 322C, 324D, 324DL, 324DLN. Its part number is 169-5594. The ring has 65 teeth. The CAT 322C securing ring is made of a material whose key feature is resistance to premature damage.