EX120-5 EX130-5 4372038 4433102 HPV091DS Hydraulic Main Pump Assembly Compatible with Hitachi

The Hitachi EX120-5 / EX130-5 Hydraulic Main Pump Assembly (OEM Part # 4372038 / 4433102 / 4465427 / HPV091DS) is a dual variable-displacement axial piston pump built for 12-to-13-ton medium excavators operating under continuous trenching, rock digging, and earthmoving jobs.

• Factory Wholesale Price: $2,500 – $4,800 USD (Direct manufacturer pricing — Save up to 50% vs regional dealer markups)
• MOQ & Bulk Discount: 1 Unit (Tiered wholesale discounts available for batch container orders)
• Lead Time: 1–3 business days (Large factory stock ready for immediate worldwide dispatch)
• Warranty: 12 Months full replacement warranty with 100% bench test video proof

Engineered with heavy-duty swashplate friction blocks and precision cylinder barrels for harsh jobsites:

• Urban Utility Trenching & Pipe Laying: Fine hydraulic metering for smooth arm and boom action during municipal utility digging with Hitachi EX120-5 excavators.
• Road Infrastructure & Earthmoving: High sustained hydraulic flow under 300 Bar working pressure for fast bucket loading cycles.
• Land Clearing & Agriculture Drainage: Thermal-resistant seal groups prevent oil bypass during long continuous operating hours in hot outdoor climates.
• Building Demolition & Foundation Prep: Reinforced pump housing protects against pressure shockwaves caused by hydraulic hammer attachments.

If your EX120-5 excavator is exhibiting hydraulic system failure, consult the diagnostic guide below:

• Fault 1: Cold Machine Operates Normally, But Machine Slows Down & Drops Pressure After 1 Hour (冷车正常,热车掉压发慢)
  Root Cause: Thermal clearance expansion wear between the piston shoes, cylinder block, and valve plate, causing internal high-pressure oil bypass.
  Solution: Replace with a complete drop-in EX120-5 main pump assembly (OEM 4372038 / HPV091DS) or overhaul the rotary group kit.
• Fault 2: Engine Stalls or Overloads When Actuating Hydraulic Boom/Arm (憋车/发动机过载熄火)
  Root Cause: HPV091DS pump regulator power-control spool jammed or pilot pressure relief valve miscalibrated.
  Solution: Recalibrate pump regulator pilot pressure or replace the complete regulator assembly to restore engine power matching.
• Fault 3: Hydraulic Oil Leakage From Drive Shaft Seal Area (主驱动轴封高压串油漏油)
  Root Cause: Clogged casing drain line causing excessive internal housing backpressure, blowing out the drive shaft skeleton seal.
  Solution: Flush housing drain lines, replace front drive shaft seal, and check gear pilot pump relief pressure.
• Fault 4: Abnormal Cavitation Noise or Severe Vibration From Main Pump (泵体异响抖动/气蚀)
  Root Cause: Air suction at inlet suction pipe, contaminated hydraulic tank filter, or worn drive shaft bearings.
  Solution: Replace suction line seals, flush hydraulic fluid tank, and replace drive shaft roller bearings.
• Fault 5: Black Metallic Filings Found Inside Hydraulic Tank Filter (油箱内有黑粉或金属屑)
  Root Cause: Severe friction galling on swashplate shoe bronze layer or cylinder block face failure.
  Solution: Flush entire hydraulic piping system, clean main control valve, and install a new EX120-5 main pump assembly.

Explore our factory-direct replacement hydraulic components compatible with major global excavator brands:

Q1: How do I verify if this main pump fits my Hitachi EX120-5 excavator?
A: Check your original pump nameplate for OEM numbers 4372038, 4433102, or HPV091DS stamp. You can also send us your machine serial number for instant fitment verification.

Q2: My EX120-5 excavator slows down after 1 hour of digging. Will replacing the HPV091DS pump fix this?
A: Yes, thermal slowdown is caused by internal pressure leakage inside the worn pump cylinder block. Installing our new EX120-5 pump restores full hydraulic speed and digging power.

Q3: Is this EX120-5 hydraulic main pump tested before shipment?
A: Yes, every single EX120-5 main pump undergoes a 5-step factory bench test, verifying pressure up to 300 Bar and volumetric efficiency above 95%. A live test video is provided before shipping.