Adjusting the Auxiliary Relief on the Yanmar VIO17: A Step-by-Step Guide

[MikePhua]

The Yanmar VIO17 is a compact, powerful mini excavator designed to work in tight spaces without sacrificing performance. One of the key features of the VIO17, like many other mini excavators, is its auxiliary hydraulic system, which powers attachments such as breakers, augers, and grapples. The performance of these attachments depends on the proper adjustment of the auxiliary relief valve, a critical component of the hydraulic system. If the auxiliary relief is not correctly set, it can lead to inefficient attachment performance, potential damage, or even system failure. In this article, we’ll walk through how to adjust the auxiliary relief on the Yanmar VIO17, discuss the common symptoms of misadjustment, and offer tips for maintaining the hydraulic system.
Understanding the Auxiliary Relief Valve in the Yanmar VIO17
The auxiliary relief valve controls the maximum pressure that can be applied to the hydraulic circuits used for operating attachments. This valve prevents the hydraulic system from exceeding safe pressure levels, which could damage components or the attachment itself. It essentially acts as a safety valve, ensuring that the hydraulic system doesn’t overload under stress.
In mini excavators like the Yanmar VIO17, the auxiliary relief valve is typically adjustable. Operators can fine-tune the relief pressure to optimize the performance of different hydraulic attachments. For example, a hydraulic hammer may require higher pressure settings than a bucket or grapple.
Common Symptoms of Misadjusted Auxiliary Relief

1. Poor Attachment Performance
   

If the auxiliary relief valve is set too low, the hydraulic attachment may not operate at full capacity. This could lead to underperformance, such as a hydraulic breaker not delivering enough impact force or an auger failing to drill at the required depth.

1. Overheating Hydraulic System
   

Conversely, if the relief valve is set too high, the system may over-pressurize, which can cause excessive heat buildup in the hydraulic fluid. This leads to inefficiency, increased wear on components, and a risk of damaging the hydraulic system.

1. Unusual Noises or Vibrations
   

Misadjusted relief settings can lead to unusual noises or vibrations when operating attachments. For instance, if the relief valve is not releasing pressure at the correct threshold, it may create a jerky or unstable motion in the attachment.
Steps to Adjust the Auxiliary Relief Valve on the Yanmar VIO17

1. Locate the Auxiliary Relief Valve
   

The first step in adjusting the auxiliary relief valve is locating it. On the Yanmar VIO17, the valve is typically found near the hydraulic pump or within the main control valve block. Consult the machine’s service manual for the exact location of the valve to avoid unnecessary disassembly or confusion.

1. Prepare the Excavator
   

Before starting the adjustment process, ensure that the excavator is in a safe, stable condition:

• Place the machine on level ground.
  
• Turn off the engine and engage the parking brake.
  
• Allow the machine to cool if it has been running to prevent burns from hot components.
  

1. Identify the Adjustment Screw
   

The auxiliary relief valve will typically feature an adjustment screw, which can be turned to either increase or decrease the relief pressure. Depending on the model of your VIO17, this screw may be located behind a protective cover or shield. If there’s no clear access, you may need to remove some covers or panels to expose the valve.

1. Use a Pressure Gauge for Accuracy
   

To make the adjustment process as precise as possible, it's recommended to use a hydraulic pressure gauge. Connect the gauge to the auxiliary circuit to monitor the pressure while making adjustments. This will give you real-time data on the pressure levels and ensure you set the correct value for optimal attachment performance.

1. Make the Adjustment
   

Once the pressure gauge is connected, begin adjusting the relief valve. Slowly turn the adjustment screw:

• Clockwise to increase the pressure.
  
• Counterclockwise to decrease the pressure.
  

Adjust the relief pressure according to the specifications recommended by the attachment manufacturer. For example, a hydraulic hammer might require a relief pressure of 2,000-2,500 psi, while lighter attachments may only require 1,500 psi.

1. Test the Adjustments
   

After making adjustments, test the operation of the auxiliary hydraulics with the specific attachment. Monitor for any abnormal behavior such as overheating, noise, or poor performance. You may need to fine-tune the relief setting based on real-world use.

1. Re-check the System
   

Once the adjustments are made and the attachment is functioning properly, double-check the entire hydraulic system for leaks or irregularities. Ensure all components are securely fastened and there are no signs of wear or damage. Periodically check the pressure settings to ensure they remain within the correct range.
Common Mistakes to Avoid During Adjustment

1. Over-adjusting the Relief Valve
   One of the most common mistakes when adjusting the auxiliary relief valve is over-tightening or over-adjusting the pressure. This can lead to over-pressurizing the system, causing unnecessary wear on hydraulic components or even system failure. Always refer to the manufacturer’s specifications to avoid incorrect adjustments.
   
2. Ignoring Attachment Specifications
   Each hydraulic attachment has specific pressure requirements. Failing to adjust the auxiliary relief valve to match the needs of your attachments can lead to poor performance and potential damage. Always consult the attachment’s manual for the correct pressure setting.
   
3. Neglecting Regular Maintenance
   Like any hydraulic component, the auxiliary relief valve should be periodically inspected and maintained. Ignoring routine maintenance can lead to issues such as valve leakage, contamination, or inaccurate pressure regulation. Make it a point to check the valve’s functionality as part of your regular equipment checks.
   

Real-World Example: Improving Attachment Efficiency
A contractor working with a Yanmar VIO17 found that their hydraulic breaker was not delivering the expected impact force. The machine was struggling to break through tough materials, and the operator noticed that the engine was overworking and the system was overheating.
Upon inspection, the auxiliary relief valve was found to be set too low, limiting the pressure available for the breaker. After adjusting the relief valve to match the recommended pressure for the hydraulic breaker, the machine's performance improved dramatically. The breaker began to deliver full impact force, and the engine no longer struggled under load. The contractor saved both time and money by making a simple adjustment, preventing unnecessary repairs and improving overall efficiency.
Conclusion: Proper Adjustment for Optimal Performance
Adjusting the auxiliary relief valve on the Yanmar VIO17 is a crucial task that can significantly affect the performance and longevity of both the machine and its attachments. By following the correct procedures, using accurate pressure gauges, and considering the specific needs of each attachment, you can ensure that your machine operates efficiently and safely. Regular maintenance and proper adjustments will keep your hydraulic system running smoothly, maximizing the productivity of your mini excavator. Whether you're working on construction sites or landscaping jobs, taking the time to properly adjust the relief valve can lead to better performance, fewer mechanical issues, and improved attachment efficiency.