9101521 Excavator Spare Parts Center Swivel Joint for ZX330-5G

The Hitachi original center swivel joint (part number: 9101521, also known as the swivel center joint) is the core rotary connecting component of the excavator hydraulic system. According to the accessory information, this part number is mainly suitable for Hitachi ZAX200, ZAX210, ZX240, ZXA330, ZAX350 and other models of excavators. For the Hitachi ZX330-5G excavator (32.4 ton class) you inquired about, as it is equivalent to the ZXA330 and ZAX350 in the 30 ton class or above, the center joint is likely to be universal.
 

The central rotary joint is a "hydraulic hub" that connects the excavator's loading (rotating platform) and unloading (chassis). Its core function is to provide continuous and uninterrupted pressure oil supply and return channels for all hydraulic actuators such as the boom, arm, bucket, slewing, and walking when the platform rotates continuously 360 degrees, avoiding entanglement of hydraulic hoses and ensuring smooth and efficient composite actions. As an original component, it adopts a high-strength shell and precision core shaft structure, with multiple independent annular oil channels inside. The oil channels are strictly isolated by high-performance rotating seals (such as Glay rings and Steller seals) to prevent internal leakage and oil circuit interconnection.

Daily inspection: It is recommended to visually inspect the exterior of the joint and surrounding pipelines for any signs of hydraulic oil leakage every 250 working hours. Regular maintenance: Combined with the major maintenance of the equipment every 2000 working hours, check the tightening torque of the fixed flange bolts, clean the oil stains and debris on the joint surface. Sealing inspection and replacement: If leakage is found, or if the wear depth of the sealing friction pair is checked during disassembly and maintenance (usually exceeding 5-10mm, it needs to be replaced) and if there are scratches or cracks on the surface, the complete set of sealing components or assemblies should be replaced in a timely manner.