4434436 Original Excavator Swing Motor Disc Spring for ZX110 ZX120 ZX135 ZX140

This genuine excavator swing motor disc spring (Part Number: 4434436), also known as a Belleville spring washer, is manufactured in strict compliance with original equipment manufacturer (OEM) technical standards. Engineered specifically for medium-duty hydraulic slewing drive systems, it delivers an exact, direct fit for Hitachi ZAXIS series excavators. Compatible applications include the ZX110, ZX120, ZX135 (including ZX135US short-tail models), and ZX140 crawler and wheeled excavators across multiple production generations. Designed to provide factory-calibrated mechanical pre-load within the swing motor brake pack and rotating group, this component directly replaces superseded and alternate OEM service part numbers. It features precise inner and outer diameters, standard conical dish height, and uniform gauge thickness, ensuring flawless alignment with mating brake friction plates, separator plates, and hydraulic release pistons. By maintaining factory-correct clamping force, it eliminates swing drift during hillside operations, restores original slewing parking brake torque, and guarantees seamless integration during scheduled swing device overhauls without requiring shimming, machining, or dimensional modifications.

Engineered to endure millions of high-frequency compression cycles, continuous hydraulic oil immersion, and severe mechanical vibration, this disc spring is fabricated from premium spring steel alloy (such as 50CrV4 / 60Si2MnA). The spring undergoes precision stamping, whole-body quenching, and specialized isothermal tempering to establish exceptional fatigue strength, high elasticity, and superior resistance to plastic deformation or load loss over time. Its surface features an anti-corrosion phosphate or blued treatment that prevents oxidation and hydrogen embrittlement in harsh hydraulic fluid environments. The precisely engineered conical profile delivers a high load-carrying capacity within an extremely compact axial footprint, providing stable, non-linear spring characteristics and uniform axial pressure distribution across the swing brake disc stack. This robust construction prevents spring cracking, eliminates pressure relaxation under high-temperature hydraulic conditions, and ensures rapid, reliable mechanical brake engagement whenever pilot pressure is released, safeguarding the excavator's upperstructure against uncommanded slewing movement.

To ensure dependable swing holding performance and prevent catastrophic swing motor failure, disc springs should be thoroughly inspected whenever the swing reduction gearbox or hydraulic motor undergoes major servicing, resealing, or brake plate replacement. Over continuous operating hours, cyclic stress and thermal exposure can lead to spring settling, loss of free height, or surface micro-cracking; therefore, spring free height and dish curvature should be measured against factory service limits and replaced as a complete matched set if deformation is detected. When reassembling the brake pack, strictly observe the correct factory stacking orientation (series or parallel configuration) to ensure proper pre-load tension and full release stroke. Always verify that mating hydraulic brake release piston seals and passages are clean and free of contamination to prevent partial brake drag, localized friction overheating, and premature spring temper loss. Maintaining clean hydraulic oil and replacing contaminated filters on schedule will maximize spring longevity and ensure smooth, reliable slewing brake operation.