Loss of Hydraulic Power in the Case 855D TBL: Troubleshooting and Solutions

[MikePhua]

The Case 855D Tracked Loader (TBL) is a reliable piece of heavy equipment widely used in construction, earthmoving, and landscaping operations. However, like any complex machine, it can experience performance issues over time. One common problem that operators may encounter is a loss of power in some hydraulic functions. This issue can severely impact the machine's efficiency, making it important to quickly diagnose and resolve. In this article, we will explore the possible causes of hydraulic power loss in the Case 855D and provide solutions for restoring optimal function.
Overview of the Case 855D TBL
The Case 855D is part of the D Series of Case Construction Equipment, designed to deliver excellent performance in demanding environments. It is equipped with a diesel engine and a hydrostatic drive system, which powers its hydraulic components, allowing the loader to lift, push, and dig effectively. The 855D’s hydraulic system is crucial for its various functions, including the lifting arms, bucket operation, and even steering.
When hydraulic power begins to fade, the 855D’s ability to perform tasks is compromised, leading to inefficiencies and potential damage to the machine over time. Recognizing the symptoms and diagnosing the issue early can prevent larger, more expensive repairs.
Understanding the Hydraulic System
The hydraulic system of the Case 855D TBL is a closed-loop system that uses hydraulic fluid to transfer power to different components, including the bucket, arms, and drive motors. It relies on several key components to work effectively:

• Hydraulic Pumps: These provide the power needed to drive hydraulic functions.
  
• Hydraulic Valves: Control the flow of fluid to various actuators and cylinders.
  
• Hydraulic Cylinders: Perform the lifting, lowering, and angling actions required by the loader.
  
• Hydraulic Fluid: The medium that transfers power throughout the system. Proper fluid levels and quality are critical for system performance.
  

If any of these components fail or experience issues, hydraulic power loss can occur, leading to diminished performance.
Common Causes of Hydraulic Power Loss
There are several potential causes for a loss of power in the hydraulic system of the Case 855D. Below are some of the most common culprits:

1. Low Hydraulic Fluid Levels
   One of the simplest causes of hydraulic power loss is insufficient fluid levels. If the hydraulic fluid drops below the required level, the system can’t generate the necessary pressure to operate the hydraulic functions efficiently. This is often the first thing to check when experiencing power loss in hydraulic functions.
   Solution: Check the hydraulic fluid level and top it up if necessary. Ensure that the fluid is clean and at the proper operating temperature. Contaminated or degraded fluid should be replaced.
   
2. Contaminated or Degraded Hydraulic Fluid
   Hydraulic fluid can become contaminated over time with dirt, debris, or water. Contaminants can clog filters and valves, leading to poor performance or a complete failure of hydraulic functions. Additionally, fluid degradation due to heat and prolonged use can reduce its effectiveness.
   Solution: Perform a fluid inspection to check for signs of contamination. If the fluid is dirty or has degraded, flush the system and replace the fluid with the manufacturer-recommended type.
   
3. Worn Hydraulic Pumps
   Hydraulic pumps are responsible for generating the flow of fluid in the system. If the pump wears out or fails, it can lead to a lack of pressure, causing a loss of hydraulic power. Symptoms of a failing pump may include inconsistent or weak hydraulic functions.
   Solution: Inspect the hydraulic pump for wear and tear. If the pump is found to be faulty, it may need to be replaced or repaired by a professional technician.
   
4. Faulty Hydraulic Valves
   The hydraulic valves control the distribution of fluid to the different hydraulic components. If a valve becomes faulty, it can lead to a reduction in fluid flow, preventing certain functions from operating at full power. This issue often presents as a partial loss of function in specific hydraulic components.
   Solution: Check the hydraulic valves for any signs of malfunction. Ensure that they are not sticking or leaking. If a valve is faulty, it should be repaired or replaced.
   
5. Clogged Filters
   Hydraulic filters remove contaminants from the fluid, ensuring that the components are protected from damage. If these filters become clogged, the system’s ability to circulate fluid properly is compromised, leading to power loss in hydraulic functions.
   Solution: Inspect the hydraulic filters and clean or replace them as needed. Regularly maintaining and replacing filters is crucial for the longevity of the hydraulic system.
   
6. Air in the Hydraulic System
   Air in the hydraulic lines can lead to inconsistent fluid flow and erratic performance. Air can enter the system through leaks, or it can be introduced during fluid changes or repairs. This leads to air pockets in the system that prevent the hydraulic components from functioning properly.
   Solution: Bleed the air from the hydraulic system. This can often be done by operating the machine through its full range of hydraulic functions to expel trapped air. Ensure all hydraulic connections are tight to prevent future leaks.
   
7. Leaks in the Hydraulic System
   Leaking hydraulic lines or fittings can cause a loss of fluid pressure, leading to a reduction in hydraulic power. Leaks can be difficult to detect, as they may occur in hard-to-see areas of the system.
   Solution: Perform a thorough inspection of the hydraulic lines, fittings, and hoses for signs of leakage. Tighten any loose connections and replace any damaged hoses or fittings to prevent further fluid loss.
   
8. Faulty Hydraulic Cylinders
   Hydraulic cylinders are responsible for lifting and moving the loader's arms and attachments. If a cylinder begins to fail, it can cause a drop in hydraulic power, leading to reduced lifting ability or slow movement.
   Solution: Inspect the hydraulic cylinders for signs of leakage, damage, or wear. If the cylinder is damaged or leaking, it may need to be rebuilt or replaced.
   

When to Seek Professional Help
While many of the issues that cause hydraulic power loss can be diagnosed and resolved by operators, some problems may require professional expertise. If the issue persists after performing basic troubleshooting or if you suspect a major component failure (such as a damaged hydraulic pump or valve), it’s recommended to consult a professional technician. They can perform a more in-depth diagnostic and repair the system using specialized tools.
Conclusion
Hydraulic power loss in the Case 855D TBL can be caused by a variety of factors, ranging from low fluid levels to damaged components. By understanding the potential causes and symptoms of this issue, operators can quickly identify and address the problem, restoring the loader's full hydraulic functionality. Regular maintenance, such as fluid checks, filter changes, and inspections of the hydraulic system, can help prevent these issues from arising in the first place, ensuring that the machine operates at peak performance for years to come.