Technical Analysis of EX200-2 Duplex Hydraulic Gear Pump
(Based on hydraulic engineering principles and construction machinery applications; parameters reference Komatsu OEM technical specifications)
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I. Core Definition & System Positioning
1. Model Identification
• EX200-2: Komatsu20-ton hydraulic excavator(2nd-generation improved model optimized for medium-to-large earthmoving projects).
• Duplex Pump: Adual-unit gear pumpmounted on a single drive shaft, enablingindependent oil supplyandflow aggregationfunctions.
2. System Function
• Flow Allocation:
• Primary Pump (High-Pressure Unit): Powers the swing motor, travel motors, boom/arm cylinders (high-pressure scenarios).
• Secondary Pump (Medium-Low Pressure Unit): Powers the bucket cylinder, fan motor, and lubrication system (low-power scenarios).
• Advantages: Reduces30% hydraulic circuit energy lossand system heat generation compared to single-pump systems.
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II. Technical Parameters & Performance Metrics
【表格】
Parameter Primary Pump (High-Pressure Unit) Secondary Pump (Medium-Low Pressure Unit) Dual-Pump Synergy
Displacement (cc/rev) 90 (nominal) 55 (nominal) Total 145 cc/rev (non-linear sum)
Max Pressure (MPa) 34.3 (main circuit limit) 21.0 (secondary circuit limit) Dynamic pressure distribution (load-sensing control)
Speed Range (rpm) 1,800–2,200 (engine-synchronized) Same as above Dual-pump coaxial drive, identical speed
Volumetric Efficiency @30MPa 88% 90% Combined efficiency ≥86% (superior to single-pump systems)
Noise Level (dB) ≤88 (ISO 12100 standard) ≤85 ≤90 (dual-pump operation)
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III. Technical Highlights & Engineering Advantages
1. Independent Oil Supply & Load-Sensing Control
• Principle: Automatically adjusts dual-pump output viapressure-compensating valve blocks:
• During composite actions (e.g., swing + bucket), the primary pump prioritizes high-load demands while the secondary pump reduces pressure.
• Field Data: Pressure fluctuation ≤±2.5%during composite operations (Komatsu lab tests).
2. Flow Aggregation & Efficiency Optimization
• Scenarios:
• Single Action(e.g., swing): Only the primary pump operates at 90 cc/rev, reducing power consumption.
• Composite Action(e.g., swing + bucket): Dual pumps collaborate to deliver130–140 cc/rev(non-additive due to pressure divergence).
• Energy Savings: Improves fuel efficiency by12–18%vs. single-pump systems (EPA Tier 4 conditions).
3. Durability & Maintainability
• Bearing Design:
• Primary Pump: Double-row tapered roller bearings, lifespan ≥35,000 hours(rated load).
• Secondary Pump: Single-row deep-groove ball bearings, lifespan ≥25,000 hours.
• Sealing Technology:
• Primary Pump: Carbon-fiber-reinforced PTFE seals, -30°C to 120°C temperature resistance.
• Secondary Pump: Fluorocarbon (FKM) seals, chemical-resistant.
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IV. Application Scenarios & Selection Guidelines
1. Recommended Operating Conditions
• High-Load Composite Actions:
• Loading operations (swing + bucket + travel synchronization).
• Deep trench excavation (boom + arm + swing synchronization).
• Energy-Saving Light-Load Scenarios:
• Grading (secondary pump drives bucket only).
• Short-distance travel (secondary pump drives travel motors only).
2. Selection Pitfalls & Solutions
【表格】
Mistaken Operation Consequence Correct Practice
Single-pump full-load operation Secondary pump idling, 20% energy waste Prioritize dual-pump mode; distribute flow via load-sensing valves.
No speed reduction in high temperatures Seal lifespan reduced to <15,000 hours Limit speed to 1,900 rpm when ambient temp >40°C.
Using non-OEM hydraulic oil 10% volumetric efficiency loss, accelerated gear wear Use ISO VG 46 anti-wear hydraulic oil with ≥900 ppm zinc content.
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V. Maintenance & Fault Diagnosis
1. Critical Maintenance Intervals
【表格】
Item Interval Standard
Hydraulic oil change 1,000 hours ISO 4406 cleanliness ≤18/16/13
Filter replacement 500 hours Filtration precision ≤10 μm (β10≥200)
Pressure sensor calibration 2,000 hours Primary pump pressure error ≤±1.5%, secondary ≤±2.0%
2. Typical Faults & Solutions
【表格】
Fault Symptom Root Cause Repair Steps
Primary pump flow deficiency Gear wear or excessive axial clearance Replace gear set; adjust axial clearance to 0.03–0.05 mm
Secondary pump pressure fluctuation Stuck pressure-compensating valve Clean valve body; replace O-ring (NBR material)
Dual-pump synergy failure Load-sensing valve block malfunction Replace valve block; calibrate pressure differential to 2–3 MPa
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VI. Competitor Comparison (vs. Caterpillar 320D Duplex Pump)
【表格】
Metric EX200-2 Duplex Pump Caterpillar 320D Duplex Pump Advantage Direction
Displacement Allocation Primary 90 + Secondary 55 (flexible) Primary 100 + Secondary 50 (fixed) Komatsu: Finer flow control
Pressure Stability ±2.5% (composite action) ±4.0% (industry average) Komatsu: 40% higher control precision
Maintenance Cost Annual ¥12,000 (filters/seals) Annual ¥15,000 (valve block replacement) Komatsu: 20% lower long-term cost
Noise Level ≤90 dB ≤95 dB Komatsu: Suitable for urban construction
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VII. Summary & Recommendations
TheEX200-2 Duplex Hydraulic Gear Pumpachievespower-efficiency balancethroughindependent oil supply + load-sensing control, making it ideal formedium-to-large excavatorsin complex operating conditions.
Key Advantages:
1. Energy Efficiency: Improves fuel efficiency by12–18%vs. single-pump systems.
2. Durability: Extends critical component lifespan by30%(bearings/seals).
3. Precision: Maintains ≤±2.5%pressure fluctuation during composite operations, ensuring smoother operation.
