4377897 Original Excavator Shim for Hitachi ZX35U ZX38U-3 ZX50U-2

Part number 4377897 is a specialized part number for Hitachi's original excavator gasket. Gaskets are thin sheet sealing elements used at the connection points of excavator components to fill gaps, prevent liquid or gas leakage, and provide cushioning and shock absorption. They are widely used in flat joint parts that require sealing, such as engines (such as cylinder heads and oil pans), hydraulic systems (such as pumps, valves, pipeline flanges), transmissions, and drive axles. As an original standard component, it may be compatible with multiple hydraulic excavators in the Hitachi ZX series (such as ZX130, ZX200, ZX250, ZX350, etc.) or EX series (such as EX120, EX200, EX300, etc.). In the aftermarket, this part is often referred to as a "sealing gasket", "adjusting gasket", or "flat gasket" based on its specific installation position.
 

This gasket is used as a static seal between two static mating surfaces. Its core function is to produce plastic or elastic deformation under the action of bolt pre tightening force, fill the micro unevenness of the joint surface, form a reliable sealing barrier, prevent oil, hydraulic oil, coolant or gas from leaking from the joint, and also compensate for small gap changes caused by machining errors, thermal expansion or vibration, protecting the joint surface from corrosion and wear. Its design can withstand high temperatures (up to 150 ℃) of excavator engines, high pressures (up to 35MPa) of hydraulic systems, and chemical corrosion of oil and coolant.

The maintenance core of this gasket lies in regular inspection, standardized replacement, and correct installation. Gaskets are disposable seals and are strictly prohibited from being reused. Usually, when disassembling, repairing, or replacing seals in related assemblies such as engines, hydraulic pumps, and valve blocks, all removed gaskets must be replaced simultaneously. Even if the appearance is intact, its sealing performance has decreased due to compression deformation. After installation, the equipment needs to be run to normal operating temperature, checked again, and the bolts tightened according to the specified torque. At the same time, maintaining the cleanliness and quality of media such as engine oil and hydraulic oil can also extend the service life of gaskets.