Converting Komatsu 220 Auxiliary Hydraulic Plumbing from Single to Double Circuit: A Detailed Guide

[MikePhua]

Overview of Auxiliary Hydraulic Systems on Excavators
Auxiliary hydraulic systems on excavators like the Komatsu 220 enable the operation of various attachments such as hydraulic thumbs, grapples, augers, and breakers. Typically, auxiliary systems come in two types:

• Single Auxiliary Circuit: Controls flow and pressure to one set of hydraulic lines, often sufficient for basic attachments
  
• Double Auxiliary Circuit: Offers two independent circuits, allowing simultaneous or more complex hydraulic functions on attachments requiring dual flow control
  

Converting from a single to double auxiliary system increases machine versatility, but it involves careful plumbing and control adjustments to ensure safe and efficient operation.
Reasons for Conversion
Operators may seek to convert their Komatsu 220 from a single to double auxiliary circuit for reasons such as:

• Using attachments with dual hydraulic functions (e.g., grapple rotation plus open/close)
  
• Improving attachment responsiveness and control precision
  
• Enhancing machine capability in demolition, forestry, or landscaping applications
  

Such a conversion extends the machine’s utility without purchasing a new excavator.
Key Components and Terminology
Understanding the hydraulic components involved is essential:

• Auxiliary Hydraulic Valve: Controls flow to auxiliary lines; needs upgrading to a dual-circuit valve or addition of a second valve
  
• Hydraulic Lines and Hoses: Tubing that carries fluid between the valve and the attachment
  
• Quick Couplers: Connect hoses to attachments quickly and securely; must match dual circuit configurations
  
• Control Lever or Joystick: Operator interface to command hydraulic flow changes
  
• Hydraulic Pump: Supplies pressurized fluid; capacity must support the additional circuit
  

Steps to Convert Single to Double Auxiliary Plumbing
1. Assess Existing System

• Identify the current auxiliary valve type and number of circuits
  
• Inspect hose routing and coupling types
  
• Review control valve compatibility with double circuit setup
  

2. Upgrade or Add Control Valve

• Replace the existing single auxiliary valve with a double auxiliary valve assembly
  
• Alternatively, install an additional auxiliary valve in series or parallel, depending on machine specifications
  
• Ensure valve spool positions correspond to control inputs
  

3. Reconfigure Hydraulic Lines

• Run separate hydraulic lines for each auxiliary circuit from the control valve(s) to the quick couplers at the boom or stick
  
• Use appropriate high-pressure hoses rated for the machine’s operating pressure
  
• Label lines clearly to avoid confusion during attachment changes
  

4. Modify Quick Couplers

• Install dual-circuit quick couplers compatible with the new lines
  
• Consider using color-coded or keyed couplers for safe and error-free attachment connections
  

5. Adjust Operator Controls

• Update or reprogram joystick or lever controls to handle dual auxiliary circuits
  
• Verify that control inputs correctly correspond to hydraulic functions
  
• Perform ergonomic tests to ensure operator comfort and precision
  

6. Test the System Thoroughly

• Check for hydraulic leaks under pressure
  
• Confirm independent operation of each auxiliary circuit
  
• Validate that flow rates and pressures meet attachment requirements
  
• Conduct safety checks to avoid unintended movement or pressure spikes
  

Terminology Glossary

• Spool Valve: A sliding mechanism within the valve that directs hydraulic fluid flow
  
• Flow Rate (L/min or GPM): Volume of hydraulic fluid delivered per minute
  
• Pressure Relief Valve: Safety valve that prevents excessive pressure
  
• Load Sense System: A feature that adjusts pump output based on demand to improve efficiency
  
• Quick Coupler: Connects hydraulic lines quickly and securely
  

Challenges and Considerations
Converting to a double auxiliary system involves challenges such as:

• Space Constraints: Limited room on the boom or stick for additional valves and hoses
  
• Hydraulic Pump Capacity: Insufficient pump flow can reduce performance or cause overheating
  
• Control Complexity: Operators may need training to handle additional functions
  
• Compatibility: Ensuring new valves and hoses match existing machine systems and attachments
  

A maintenance crew working on a Komatsu 220 in Europe shared that upgrading to double auxiliary plumbing allowed them to switch between a hydraulic shear and a rotating grapple on the fly, significantly speeding up demolition work in urban sites.
Maintenance Tips Post-Conversion

• Routinely inspect new hoses and fittings for wear and leaks
  
• Maintain cleanliness of hydraulic fluid and replace filters regularly
  
• Monitor valve operation and address sticking or delayed responses promptly
  
• Keep control linkages lubricated and calibrated
  

Case Study: Improved Jobsite Productivity
A landscaping company in the Midwest retrofitted their Komatsu 220 with a double auxiliary system to operate a rotating grapple and hydraulic thumb simultaneously. Previously, they had to manually swap attachments or use multiple machines. Post-upgrade, they reported a 40% reduction in cycle times for tree removal and site cleanup, directly translating to higher profits and customer satisfaction.
Conclusion
Converting a Komatsu 220 from single to double auxiliary hydraulic plumbing is a practical upgrade that significantly expands the machine’s functionality. With careful planning, correct component selection, and thorough testing, operators can enjoy enhanced control over complex attachments. This conversion not only improves versatility but also boosts productivity and safety across diverse heavy equipment applications.