A: Look for "boom drift," where the boom slowly lowers while the controls are in neutral, or visible hydraulic oil leaking down the cylinder rod. If you notice jerky boom movements or external oil pooling around the cylinder head, the internal seals or rod wipers have likely reached their wear limit.
A: Cleanliness is paramount; ensure the rod and cylinder bore are free of debris. Always lubricate new seals with fresh hydraulic oil before assembly. Use professional seal expanders to avoid twisting the U-cups or nicking the sealing lips, which can cause immediate leaks upon startup.
A: Cross-reference the OEM part number 4448398 with your machine's parts manual. This kit is specifically designed for the boom cylinder of Hitachi ZX200 and ZX330 series. Checking the cylinder rod diameter and seal configuration against your service records will ensure 100% compatibility.
A: Our kit is formulated for thermal stability, maintaining its structural elasticity in temperatures ranging from -35°C to 110°C. The high-performance TPU prevents seal hardening in cold climates and resists extrusion under the intense thermal loads common in heavy-duty open-pit mining operations.
Q: What quality options are available?
A: We provide original, OEM, and high-quality aftermarket versions with stable supply capability.
Q:Why Choose RITO?
A:Listed Factory
Stable&Reliable Quality
OEM Factory for Chinese Top Excavator Brands
Supplier to Fortune 500 Companies





















