3106174 Main Pump Servo Piston Hitachi Hydraulic Pump Parts HPV145 (ZX330 / EX300) Hydraulic Excavator Pump Excavator Spare Parts

Technical specifications

Fits this Hitachi machine

It is used on the Hitachi HPV145 (ZX330 / EX300) excavator. Send us the machine serial and the number plate or photos of the old unit and we will confirm the part before dispatch. Browse our Hitachi parts and hydraulic pump parts range.

Why fit this main pump servo piston

• Correct flow and pressure - matched to the original displacement so cycle times come back to spec.
• Lapped mating faces - cylinder block and valve plate are lapped to hold pressure without internal leakage.
• Direct replacement - mounting flange, shaft spline and port positions match the original unit.
• Tested before packing - every unit is run on the bench, so it arrives ready to fit.

Signs this main pump servo piston needs replacing

• Slow cycle times - weak boom or arm, and the machine stalls under load.
• Whining or knocking - from the pump, louder as the oil warms up.
• Oil overheating or foaming - with metal particles found in the tank.
• Loss of power - on one side of the machine, or drift in the travel circuit.

If your HPV145 (ZX330 shows any of these signs, replacing the part is the fastest way back to full production.

Installation notes

• Flush the tank and replace the suction filter before fitting a new pump.
• Check the coupling and pump drive for wear, a worn coupling will ruin the new pump.
• Fill the pump case with clean oil before start-up and bleed the circuit.
• Run at low load and check pressure at the test ports before full production work.

Q: Which machines does this main pump servo piston fit?

A: Hitachi HPV145 (ZX330 / EX300). Send your machine serial number and a photo of the old part so we can cross-check before ordering.

Q: What does this part do?

A: It draws oil from the hydraulic tank and delivers it under pressure to the main control valve, which feeds the boom, arm, bucket and travel circuits.

Q: How do I know it needs replacing?

A: Watch for slow cycle times, whining or knocking and oil overheating or foaming. Any of these on a working machine usually means the part is at the end of its life.

Q: Is this an original Hitachi part?

A: This is an OTTO aftermarket part built to replace Hitachi 3106174. It is not a Hitachi branded part. We also quote genuine parts on request.

Q: What are the lead time, shipping and payment terms?

A: In-stock units ship within 1-3 working days. We ship worldwide by DHL, TNT, UPS, air or sea freight with export packing. Trade terms: EXW, FOB, CIF or DDP; payment by T/T, Western Union, L/C or Paypal.

Q: Why choose OTTO?

A: Listed manufacturer and exporter with 20+ years in excavator parts.
OEM quality at competitive prices; components tested before shipment.
Stable supply and export packing for wholesale and dealer programs.
Worldwide shipping with full documents and after-sales support.