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Hydraulic Piston Pumps for Excavators: OEM-Quality Axial Piston Pump Replacements for Komatsu, CAT, Hitachi & More

A hydraulic piston pump is the most technically advanced and highest-performing pump type within your excavator's hydraulic parts system, engineered specifically to meet the variable high-pressure demands of modern excavator working circuits. Unlike gear pumps, which deliver fixed-displacement flow, axial piston pumps use a variable-angle swashplate mechanism to continuously modulate their displacement output in real time, increasing flow under light load for speed and reducing displacement under heavy load to maintain pressure and protect the system.

When a piston pump begins to wear internally, the precision tolerances between pistons, cylinder barrel, and valve plate are the first to degrade, causing internal bypass that reduces effective pressure, wastes energy as heat, and accelerates wear in every downstream component the pump is feeding. Imara Engineering holds high-demand piston pump assemblies in ready stock for fast dispatch internationally.

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117 products

Hydraulic Piston Pump 142-8698 / 155-9128 / 155-9248 for CAT

Hydraulic Piston Pump 142-8698 / 155-9128 / 155-9248 / 169-4883 / 173-3420 / 395-5894 / 178-9181 for CAT – Construction Equipment

Regular price $2,800.00
Sale price $2,800.00 Regular price $590.00
Hydraulic Piston Pump 213-5268 CAT 988G 988H AD55E – Loader

Caterpillar

Hydraulic Piston Pump 213-5268 for CAT 988G 988H AD55E – Loader

Regular price $2,150.00
Sale price $2,150.00 Regular price $961.53
Hydraulic Piston Pump 307-3063 / 20R-6569 for CAT 426 416E

Hydraulic Piston Pump 307-3063 / 20R-6569 for CAT 426 416E 416F 416F2 422F 422F2 428F 434F 415F2 – Backhoe Loader

Regular price $2,576.00
Sale price $2,576.00 Regular price $1,288.00
Hydraulic Piston Pump 350-0666 for CAT 416E 422E 428E 434E

Caterpillar

Hydraulic Piston Pump 350-0666 for CAT 416E 422E 428E 434E – Loader

Regular price $2,595.00
Sale price $2,595.00 Regular price $398.00
Hydraulic Pump 167-1153 for CAT Excavators Main Piston Pump

Caterpillar

Hydraulic Pump 167-1153 for CAT Excavators – Main Piston Pump

Regular price $2,800.00
Sale price $2,800.00 Regular price $8.00
Hydraulic Piston Pump 161-6634 CAT 416C 426C 428C 436C 438C

Caterpillar

Hydraulic Main Piston Pump 161-6634 for CAT 416C 426C 428C 436C 438C – Backhoe Loader

Regular price $2,500.00
Sale price $2,500.00 Regular price $468.00
Hydraulic Main Piston Pump 122-1206 for CAT TH62 TH63

Caterpillar

Hydraulic Main Piston Pump 122-1206 for CAT TH62 TH63 TH82 TH83 – Telehandler

Regular price $2,500.00
Sale price $2,500.00 Regular price $900.00
Hydraulic Piston Pump 224-6369 for CAT 420D 430D 432D 442D

Caterpillar

Hydraulic Piston Pump 224-6369 for CAT 420D 430D 432D 442D – Backhoe Loader

Regular price $2,500.00
Sale price $2,500.00 Regular price $450.00
Hydraulic Main Piston Pump 209-3258 for CAT 980G – Loader

Caterpillar

Hydraulic Main Piston Pump 209-3258 for CAT 980G – Wheel Loader

Regular price $2,210.00
Sale price $2,210.00 Regular price $1,105.00
Hydraulic Fan Piston Pump 235-2716 CAT 980H – Wheel Loader

Hydraulic Fan Piston Pump 235-2716 for CAT 980H – Wheel Loader

Regular price $2,460.00
Sale price $2,460.00 Regular price $600.00
Hydraulic Fan Motor & Piston Pump 266-8034 for CAT 330D

Hydraulic Fan Motor & Piston Pump 266-8034 for CAT 330D 345B – Excavator

Regular price $2,895.00
Sale price $2,895.00 Regular price $398.00
Hydraulic Piston Pump 157-6081 for CAT D5N with 3126B

Hydraulic Piston Pump 157-6081 for CAT D5N, D5N XL, D5N LGP with 3126B Engine – Dozer

Regular price $2,800.00
Sale price $2,800.00 Regular price $1,100.00
Hydraulic Piston Pump 254-5147 CAT 966H 972H – Wheel Loader

Hydraulic Piston Pump 254-5147 for CAT 966H 972H – Wheel Loader

Regular price $2,900.00
Sale price $2,900.00 Regular price $450.00
Hydraulic Piston Pump 100-3259 for Caterpillar Excavators

Hydraulic Piston Pump 100-3259 for Caterpillar Excavators

Regular price $2,200.00
Sale price $2,200.00 Regular price $500.00
Hydraulic GP-Piston Pump 9T6857 for Backhoe Loader 416F 428F

Hydraulic GP-Piston Pump 9T6857 9T-6857 for Backhoe Loader 416F 428F

Regular price $2,150.00
Sale price $2,150.00 Regular price $1,288.00
Fan Motor Drive Piston Pump 31Q9-30212 for Hyundai R380-9

Fan Motor Drive Piston Pump 31Q9-30212 for Hyundai R380-9, R480-9 Excavator

Regular price $1,750.00
Sale price $1,750.00 Regular price
Piston Pump 3629620 362-9620 for Cat 988K Wheel Loader

Piston Pump 3629620 362-9620 for Cat 988K Wheel Loader

Regular price $12,950.00
Sale price $12,950.00 Regular price
Rebuilt Hydraulic Pump 6E-5072 for Caterpillar 160G 12G 140G

Hydraulic Piston Pump 6E-5072 6E5072 Rebuild for Caterpillar 160G, 12G, 140G, 130G Motor Graders

Regular price $3,032.00
Sale price $3,032.00 Regular price
Piston Pump VOE22032988 22032988 for Volvo B11R Bus / Coach

Piston Pump VOE22032988 22032988 for Volvo B11R Bus / Coach

Regular price $2,500.00
Sale price $2,500.00 Regular price

Collection: Piston Pumps

How Does a Hydraulic Piston Pump Work?

An axial piston pump contains a rotating cylinder barrel holding multiple pistons, typically seven or nine, arranged in a circular pattern parallel to the drive shaft axis. As the barrel rotates, the pistons reciprocate in and out of their bores against a tilted swashplate, alternately drawing fluid in on the intake stroke and expelling it under pressure on the discharge stroke. The angle of the swashplate determines the stroke length of each piston, which directly controls the displacement output of the pump.

On a variable-displacement pump, a servo control mechanism adjusts the swashplate angle automatically in response to system pressure and flow demand signals from the machine's hydraulic control system. When the operator commands a light, fast movement, the swashplate angle increases to maximise flow. When the machine is under heavy digging load, and pressure rises, the swashplate angle reduces to limit flow and maintain pressure within safe operating limits. This continuous real-time adjustment is what makes axial piston pumps so well suited to the highly variable load cycles of excavator work.

Common Symptoms of Hydraulic Piston Pump Failure

Piston pump degradation follows a predictable pattern as internal components wear beyond their tolerance limits. These are the key symptoms to monitor:

  1. Progressive loss of digging force — As internal bypass increases between worn pistons and the cylinder barrel, effective system pressure drops gradually. This is the most consistent early indicator of piston pump wear.
  2. Slow cycle times across all functions — Reduced pump output flow affects boom, arm, bucket, swing, and travel speeds simultaneously, distinguishing it from a single-circuit fault.
  3. Hydraulic oil overheating — Internal bypass converts lost pressure energy directly into heat, causing the hydraulic oil temperature to climb beyond normal operating range.
  4. High-pitched whine or knock from the pump — Worn piston slippers, damaged valve plates, or cavitation inside the pump barrel generate audible noise at operating speed.
  5. Pump case drain flow exceeding specification — Excessive case drain flow measured at the drain port is one of the most reliable diagnostic indicators of advanced internal pump wear.
  6. Reduced performance at low engine RPM — A worn piston pump struggles to maintain adequate flow at lower engine speeds, causing functions to slow or drop out when the operator reduces the throttle.

If you are observing case drain flow above manufacturer specification limits alongside any combination of the above symptoms, the piston pump requires immediate replacement to prevent progressive damage to downstream hydraulic components.

Piston Pump Models We Supply

Imara Engineering supplies hydraulic piston pump assemblies for a wide range of excavator models and production series. Our most commonly supplied units include:

  • Komatsu — PC200-7, PC200-8, PC210-8, PC300-7, PC300-8, PC360-7, PC400-7, PC400-8, PC450-8
  • Caterpillar (CAT) — 320C, 320D, 320D2, 323, 325C, 325D, 330C, 330D, 336D, 336E
  • Hitachi — ZX200-3, ZX210-3, ZX300-3, ZX330-3, ZX450-3, ZX500, EX200-5, EX300-5
  • Volvo — EC210B, EC240B, EC290B, EC380, EC480, EC700
  • Doosan — DX225LC, DX300LC, DX380LC, DX480LC
  • Kobelco — SK200-8, SK300, SK350-8, SK480, SK850
  • Hyundai — R210LC-9, R290LC-9, R380LC, R480LC
  • Case — CX210, CX300, CX350, CX470

Cannot find your model listed? Contact our parts team with your machine serial number and OEM part number, and we will confirm the correct piston pump assembly for your specific unit immediately.

Variable Displacement vs Fixed Displacement Piston Pumps

Not all piston pumps use variable displacement. Understanding the difference ensures you source the correct replacement for your application:

  • Variable Displacement Axial Piston Pumps — The standard pump type on all modern mid-to-large excavators. The swashplate angle adjusts automatically to match system demand, providing both high performance and fuel efficiency. These pumps are more complex internally and require precision manufacturing to maintain performance over time.
  • Fixed Displacement Axial Piston Pumps — Used in applications where a constant, predictable flow rate is required regardless of system pressure. Less common on modern excavators but found in certain hydraulic drive circuits, winch systems, and specialised attachments.
  • Bent-Axis Piston Pumps — A variant of the axial piston design where the cylinder barrel axis is angled relative to the drive shaft rather than aligned with it. Used in some travel motor and high-torque drive applications rather than as a main pump unit.

When ordering, our parts team will confirm the exact pump variant and displacement specification required for your machine model and circuit application.

Piston Pump Rebuild vs Full Replacement

One of the most common decisions when a piston pump fails is whether to rebuild the existing unit or replace it with a completely new assembly. Here is how to approach that decision:

  • Rebuild is appropriate when the pump housing, cylinder barrel, and shaft are dimensionally within tolerance, and failure is limited to worn piston slippers, valve plate scoring, or seal degradation. A quality rebuild kit restores internal clearances and delivers performance close to a new unit at significantly lower cost.
  • Full replacement is appropriate when the cylinder barrel bore is worn beyond tolerance, the shaft journal shows damage, the housing has cracking or severe scoring, or the pump has suffered a catastrophic internal failure from contamination or oil starvation. In these cases, a complete assembly replacement is the only reliable solution.

Imara Engineering supplies both complete piston pump assemblies and dedicated pump seal and repair kits, giving you the flexibility to choose the most cost-effective solution for your specific situation.

Related Hydraulic Parts You May Need

Piston pump replacement or rebuild often requires attention to the wider hydraulic system. Consider sourcing these components alongside your piston pump:

  • Main Hydraulic Pumps — Complete main pump assemblies where the piston pump is supplied as an integrated unit
  • Pilot Pumps — Inspect and replace the pilot pump simultaneously when replacing in a tandem assembly
  • Pump Seal Kits — For piston pump rebuilds covering all internal seals, o-rings, and valve plate components
  • Control Valves — Inspect the main control valve for contamination damage after any piston pump failure
  • Hydraulic Hoses & Pipes — Replace pump inlet and outlet hoses when fitting a new pump assembly

Frequently Asked Questions

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