Hitachi ZW 550-6 Operator's Manual page 305

9. One point each to upper and lower center hinge pins
(14 and 15).
--- every 250 hours
Upper (14)
Lower (15)
10. One point each to front and rear axle support pins
(16 and 17).
--- every 10 hours
MAINTENANCE
7-21
14
15
MNHE-07-010
16,17
MNHE-07-012