4654751 Excavator Parts Servo Piston for ZX120-3

Hitachi excavator original servo piston, universal part number 4654751, is the core control component in hydraulic pump systems. This accessory is mainly suitable for Hitachi ZX series small and medium-sized excavators, including ZX110-3, ZX120, ZX130 and other models. Meanwhile, according to the information from the original parts supplier, this servo piston is also widely applicable to many other models of Hitachi excavators, such as ZX60, ZX70, ZX160LC-3, ZX200-3, ZX240-3 ZX series, as well as some models of EX100, EX200, EX300 EX series.
 

The servo piston 4654751 is a key actuator component in the inclined disc axial piston variable displacement pump. Its core function is to respond to changes in pilot control oil pressure, drive the inclined plate to change the tilt angle, and accurately and continuously adjust the displacement and output flow of the hydraulic pump, ultimately achieving wireless speed and force control of excavator working devices (such as boom, arm, bucket). This component is usually made of high-strength alloy steel through precision machining, with extremely high dimensional accuracy, surface smoothness, and wear resistance. Its structural design needs to ensure smooth and sensitive reciprocating motion under the action of high-pressure hydraulic oil, and amplify the small pilot pressure signal into a large force sufficient to drive the inclined plate.
 

Servo pistons are precision components of hydraulic systems and need to be inspected in conjunction with regular maintenance of hydraulic pumps. It is recommended to conduct professional testing on the hydraulic system every 2000 hours of operation or annually, with a focus on the stability of system pressure and whether there is any delay in response speed. If there is slow or weak movement of the entire machine or abnormal noise from the pump body, after eliminating problems such as oil and filter element, the hydraulic pump needs to be disassembled and inspected, with a focus on checking whether the servo piston surface has any strains, wear, scratches, and whether the valve body holes that match it have any wear. Maintaining the cleanliness of hydraulic oil is crucial, and it is necessary to regularly replace hydraulic oil and filter cartridges that meet specifications to prevent contaminants from causing piston sticking or wear.