Volvo 120H Hydraulic System Troubleshooting and Maintenance: A Complete Guide

[MikePhua]

The Volvo 120H wheel loader is renowned for its powerful and efficient hydraulic system, which drives the machine’s lifting and digging capabilities. However, like all hydraulic systems, it can sometimes face issues that may hinder its performance. Whether you are a seasoned operator or new to the Volvo 120H, understanding its hydraulic system and common problems can help ensure smooth operation and prevent costly downtime. This article provides a comprehensive guide to troubleshooting and maintaining the Volvo 120H’s hydraulic system.
Understanding the Volvo 120H Hydraulic System
At the heart of the Volvo 120H’s functionality is its hydraulic system, which powers various components of the machine, including the lift arms, bucket, and steering. The system relies on hydraulic fluid to transmit power through hydraulic pumps, cylinders, and valves. These components work together to perform heavy lifting, digging, and pushing tasks.
Hydraulic power is essential for the loader’s performance. However, the system is highly sensitive to any changes in fluid pressure, flow, or contamination. As such, regular maintenance and prompt attention to any issues can keep the machine running smoothly.
Common Hydraulic Problems in Volvo 120H
Despite its robust design, the hydraulic system in the Volvo 120H can face several common issues. Understanding these potential problems and their causes will help operators troubleshoot effectively.
1. Low Hydraulic Pressure
One of the most frequent issues in any hydraulic system is low hydraulic pressure. When the system doesn't generate enough pressure, it may cause sluggish operation of the lift arms or bucket, reduced steering performance, or even complete failure to lift or move the machine.

• Symptoms: Slow or weak lifting of the loader arms, reduced bucket performance, and sluggish steering response.
  
• Possible Causes:
  • Low hydraulic fluid levels.
    
  • Leaking hydraulic lines or fittings.
    
  • Faulty hydraulic pump.
    
  • Blocked or damaged hydraulic filters.
    
• Solution: Check the hydraulic fluid level and top it up if needed. Inspect all hydraulic lines for leaks or damage. Replace clogged or damaged filters. If the issue persists, the hydraulic pump may need servicing or replacement.
  

2. Hydraulic Fluid Contamination
Contaminants in hydraulic fluid can cause severe damage to the hydraulic system components. Dirt, water, or metal particles can block the flow of fluid, increase wear and tear, and cause erratic movement or a complete breakdown of the system.

• Symptoms: Jerky or uneven movement, slow response time, and overheating.
  
• Possible Causes:
  • Contaminated fluid entering the system through open ports.
    
  • Poor quality fluid used during maintenance.
    
  • Damaged or worn-out seals.
    
• Solution: Regularly replace hydraulic fluid and use high-quality, manufacturer-approved fluid. Install and maintain proper filtration systems. If contamination is severe, perform a full system flush to remove debris and contaminants.
  

3. Overheating of the Hydraulic System
Overheating in the hydraulic system can occur when the fluid temperature exceeds normal operating levels. High temperatures reduce the fluid’s viscosity, leading to decreased efficiency and potential damage to seals, valves, and other components.

• Symptoms: The loader becomes sluggish, overheating warnings are triggered, and the hydraulic fluid appears excessively hot.
  
• Possible Causes:
  • Low fluid levels.
    
  • Contaminated hydraulic fluid.
    
  • Faulty or blocked hydraulic cooling system.
    
  • Overuse or excessive load placed on the loader.
    
• Solution: Regularly check the fluid level and ensure that the system is adequately cooled. Clean the hydraulic cooler and ensure proper airflow. Avoid overloading the machine beyond its rated capacity, which could strain the hydraulic system.
  

4. Slow or Jerky Movement
When the loader exhibits jerky or slow movement, it is often a sign of a malfunctioning hydraulic valve or control system. This can also happen if the system is not receiving the correct amount of fluid or if the hydraulic pressure is inconsistent.

• Symptoms: The loader arm moves in an erratic or stuttering manner. The bucket may also struggle to reach its maximum height or operate smoothly.
  
• Possible Causes:
  • Air trapped in the hydraulic system.
    
  • Faulty or worn-out hydraulic control valves.
    
  • Leaking hydraulic lines.
    
  • Faulty hydraulic pump.
    
• Solution: Bleed the hydraulic system to remove trapped air. Inspect and repair or replace any faulty control valves, pump components, or hoses. Also, ensure that the hydraulic fluid is at the correct level and that there are no leaks.
  

5. Steering Problems
A common problem with the Volvo 120H’s hydraulic steering system is difficulty turning or steering issues. The steering system in this model relies on hydraulic power to function smoothly, and any issues here can significantly affect machine handling.

• Symptoms: The loader is difficult to steer, particularly at low speeds. There may be increased effort required to turn the wheel or erratic behavior in steering response.
  
• Possible Causes:
  • Low hydraulic fluid in the steering system.
    
  • Faulty steering valves or cylinders.
    
  • Air in the hydraulic lines.
    
  • Leaking or damaged hoses.
    
• Solution: Check the hydraulic fluid level specific to the steering system and top it up as necessary. Inspect steering valves and cylinders for wear or leaks. Bleed the steering system to remove any trapped air.
  

Routine Maintenance for the Volvo 120H Hydraulic System
To keep your Volvo 120H’s hydraulic system operating efficiently, regular maintenance is essential. Here are some key maintenance steps that should be part of a regular service schedule:

• Fluid Checks: Regularly inspect the hydraulic fluid level, especially before starting work. If the fluid level is low, top it up immediately using the recommended fluid. Always check for signs of contamination and ensure the fluid is clean.
  
• Filter Replacements: Replace hydraulic filters as per the manufacturer's recommended intervals. Dirty or clogged filters can reduce system performance and lead to component damage.
  
• Check for Leaks: Inspect all hydraulic hoses, fittings, and connections for leaks. Replace any worn or damaged parts immediately to prevent fluid loss and further damage.
  
• System Bleeding: If you suspect air in the system, perform a bleeding procedure to ensure proper fluid flow and smooth operation.
  
• Regular Inspection: Inspect the hydraulic pump, valves, and cylinders for wear or damage. Listen for any unusual noises that could indicate an internal issue within the hydraulic components.
  

Real-World Example: Volvo 120H Hydraulic System Failures
A well-known case of hydraulic failure in a Volvo 120H occurred in a construction company operating in a busy urban area. The loader started exhibiting slow movements and a lack of power, particularly when lifting heavy materials. The problem was initially misdiagnosed as a hydraulic pump failure, but further investigation revealed that the issue was due to contaminated hydraulic fluid, which had led to pump damage. Once the fluid was replaced and the system flushed, the loader returned to optimal performance, saving the company from unnecessary pump replacement costs.
Conclusion
The Volvo 120H is a powerful and efficient machine when its hydraulic system is in good working order. Regular maintenance, attention to detail, and understanding the common issues that arise with hydraulic systems will help ensure smooth operation and longevity for the loader. By following the troubleshooting and maintenance tips outlined in this guide, operators can avoid unexpected downtime and keep their Volvo 120H performing at its best.