Hydraulic Center Swivel Joint 9101521 9156877 for Hitachi Excavators Center swivel joint 9101521 / 9156877 for Hitachi excavators - the hydraulic rotary joint that transfers oil between the upper structure and the undercarriage. Fits EX100, EX120, EX200, EX220, ZX200, ZX210, ZX225US, ZX270, ZX330, ZAX240 and ZAX330 applications. Key Features Hydraulic center swivel joint (center joint / rotary joint) OEM part number 9101521, also referenced as 9156877 Serves the EX and ZX