4287249 Original Excavator Parts Arm Spacer Gasket for ZX160LC-3 ZX200-3 ZX200-5G ZX120-3 ZX160 ZX20

This original specification boom shim (also known as an axial adjustment spacer) is specifically customized for the front-end working device of **Hitachi** medium-duty excavators. Manufactured with high precision according to the official part number **4287249**, it perfectly fits the main crawler excavator series such as the Hitachi EX200-2, ZX200-3, ZX210LC-3, ZX240LC-3, and ZX250. This shim is mainly deployed on the hinged end faces of the boom, stick, and linkage mechanisms. Standardized dimensional tolerances ensure a high degree of fit with the original pins and bushings, eliminating axial clearances on the end faces of the working device caused by long-term operation, ensuring precise mechanical coordination of the entire machine during heavy-duty excavation.

This boom shim uses high-quality **high-carbon alloy steel** or high-hardness spring steel as the base material, undergoing precision cold rolling and digital stamping processes. The product surface undergoes deep quenching heat treatment, giving it both "hard exterior and tough interior" physical properties—high surface hardness, providing excellent compressive, shear, and wear resistance; and a strong substrate with high fatigue strength, capable of efficiently bearing instantaneous high loads. The gasket has extremely high flatness, ensuring uniform stress on the bearing surface and effectively suppressing physical yielding or edge curling under alternating impact conditions. Its core performance focuses on **high rigidity and low coefficient of friction**, aiming to lock in the absolute structural rigidity of the mechanical joint.

When overhauling the working device or replacing the pin, the axial clearance of the joint end face must be accurately measured using measuring tools. By combining or configuring **4287249 gaskets**, the axial clearance must be strictly controlled within the original factory safety limits (usually less than 1mm). Before assembly, high-entropy sludge and sand particles must be thoroughly removed from the contact surfaces, and heavy-duty extreme pressure grease must be applied evenly. During routine maintenance, the tightness and signs of uneven wear of each joint should be checked regularly. If cracks are found at the edge of the gasket or the thickness deformation exceeds the standard, it must be replaced in pairs in time to prevent excessive gaps from causing unilateral load and damaging the forearm body structure.