Switching Controls on the Komatsu PC120 without a Pattern Control Valve

[MikePhua]

The Komatsu PC120 is a versatile and widely used hydraulic excavator that is known for its robust performance in construction and heavy-duty operations. It is equipped with a variety of control systems that help the operator maneuver the machine with ease. One common feature among hydraulic excavators, including the Komatsu PC120, is the ability to switch the control pattern to suit the operator's preference or comfort. The most common pattern switching method is through a pattern control valve. However, some models may lack this specific valve or it may be unavailable for various reasons. So, how can operators switch the controls without this crucial component? This article discusses the ways to switch the control pattern on the Komatsu PC120 without using a pattern control valve.
Understanding the Importance of Control Patterns
In any hydraulic excavator, the control pattern refers to the way in which the operator manipulates the controls to move the boom, arm, bucket, and track. The two primary control patterns are:

• ISO Pattern: Also called the "cat pattern," where the right joystick controls the boom and bucket, and the left joystick controls the swing and arm.
  
• SAE Pattern: Also known as the "John Deere pattern," where the right joystick controls the arm and swing, while the left joystick controls the boom and bucket.
  

Switching between these two control patterns is often necessary for operators to maintain comfort, efficiency, or based on their previous experience with a different type of machine. In most modern machines, switching patterns is facilitated through a pattern control valve that allows for easy reconfiguration of the joystick functions.
The Challenge of Switching Controls without a Pattern Control Valve
When a pattern control valve is not present or is malfunctioning, the typical method of switching between patterns becomes unavailable. This can be frustrating for operators, as they may be accustomed to one pattern and find it challenging to operate in the alternative pattern. Thankfully, there are solutions and methods for switching the control patterns without relying on this specific valve.
Methods to Switch Controls without a Pattern Control Valve
1. Manual Reconfiguration of Joystick Linkages
In older excavator models, including some versions of the Komatsu PC120, it is possible to manually reconfigure the joystick linkages to change the control pattern. This method requires removing the joystick panels and adjusting the hydraulic linkages that control the movements of the boom, arm, and bucket.

• Process:
  • Disconnect the electrical and hydraulic connections for the joystick controls.
    
  • Manually swap the hydraulic hoses or linkages to the appropriate components.
    
  • This process can be labor-intensive and may require specific knowledge of the machine’s hydraulic system.
    

While this method can be effective, it is not the most convenient or time-efficient way to switch patterns. Furthermore, it may not always be feasible depending on the machine’s configuration and the hydraulic setup.
2. Using a Retrofit Kit
Some aftermarket companies offer retrofit kits for excavators that allow operators to switch the control pattern without requiring the original pattern control valve. These kits typically consist of hydraulic valves and joystick adapters that can be installed to modify the existing control system.

• Benefits:
  • Easy to install: Retrofit kits are designed to be installed with minimal modifications to the machine.
    
  • Cost-effective: These kits are often cheaper than replacing or installing a full pattern control valve.
    
  • Versatility: Some retrofit kits allow operators to switch between patterns with a simple lever or switch, improving overall operational efficiency.
    

These kits are often designed to be compatible with a variety of excavators, including Komatsu PC120, and can be a reliable solution for machines lacking a built-in pattern control valve.
3. Electrical Pattern Selector Switch
In some cases, it may be possible to install an electrical pattern selector switch. This is an electronic solution where operators can change the control pattern at the push of a button or flip of a switch. These switches typically work by electronically controlling the hydraulic valves or actuators that manage the movement of the joysticks.

• How It Works:
  • The electrical selector switch is installed between the joystick controls and the hydraulic system.
    
  • Pressing the button or flipping the switch causes the hydraulic system to reconfigure, changing the pattern from ISO to SAE or vice versa.
    
  • This method is often used in more modern machines, but may be adaptable to older models with some custom wiring and control adjustments.
    

While this solution requires some installation, it offers a convenient and user-friendly method of switching control patterns.
Considerations When Switching Control Patterns
When switching between different control patterns, it is essential to keep in mind a few considerations:

• Operator Training: Switching patterns may cause initial confusion for operators who are used to one pattern. It's important to ensure that operators are familiar with the changes and receive proper training if switching between patterns regularly.
  
• Hydraulic System Impact: In some cases, modifying the control pattern may affect the hydraulic flow or performance of the machine. It’s crucial to test the machine after the modification to ensure that all functions are working as intended.
  
• Maintenance: Regular maintenance is vital to ensure that the hydraulic system remains efficient and the control system operates smoothly. Any modification should be inspected periodically to ensure no issues arise from improper configuration.
  

Conclusion
Switching the control pattern on a Komatsu PC120 without a pattern control valve is entirely possible, and operators can explore various methods such as manual reconfiguration, installing retrofit kits, or using electrical pattern selector switches. Each option has its advantages and disadvantages, so the method chosen should depend on the operator's needs, the machine’s configuration, and the desired level of convenience.
By taking the time to understand the machine's hydraulic system and exploring aftermarket solutions, operators can ensure that their Komatsu PC120 functions optimally, regardless of whether a pattern control valve is available. As excavators continue to evolve with more advanced technology, finding efficient solutions for control pattern switching can improve operator productivity and comfort, ultimately contributing to more successful projects.