Case 850B Loss of Hydraulics: Diagnosis and Solutions

[MikePhua]

The Case 850B is a powerful crawler dozer used in a variety of heavy construction and earthmoving tasks. Like many large pieces of machinery, its performance relies heavily on its hydraulic system to operate key functions such as lifting, pushing, and tilting. When the hydraulics on a Case 850B fail or exhibit a loss of power, it can lead to significant delays and costly downtime. Understanding the common causes of hydraulic failure and how to troubleshoot the issue is crucial for keeping the dozer running efficiently. This article provides a detailed guide on diagnosing and solving hydraulic problems in the Case 850B.
Understanding the Case 850B and Its Hydraulic System
The Case 850B is part of the Case series of crawler dozers, which are designed for tasks such as grading, excavation, and land clearing. The 850B model is particularly known for its strong pushing power, robust design, and excellent performance in tough terrains. Its hydraulic system is essential to its operation, providing power to components like the blade, tracks, and steering system. The hydraulic system includes a pump, hydraulic fluid, valves, cylinders, and hoses that work in unison to move the machine's parts.
The hydraulic system in the Case 850B is powered by a hydraulic pump, which is typically driven by the engine. This pump circulates hydraulic fluid through a series of valves, lines, and actuators that perform tasks like lifting and tilting the blade or driving the tracks. A loss of hydraulic power can result from various issues within the hydraulic system, including low fluid levels, pump failure, valve malfunctions, or clogged filters.
Common Causes of Hydraulic Failure in the Case 850B

1. Low Hydraulic Fluid Levels
   • One of the most common reasons for a loss of hydraulic power is low fluid levels. Hydraulic fluid is essential for transferring power and maintaining the system's pressure. If the fluid is low, the pump cannot generate enough pressure to perform the necessary operations.
     
   • Cause: Leaks in the hydraulic lines, seals, or cylinders can cause gradual fluid loss. Over time, if fluid is not replenished, the system will fail to function properly.
     
2. Contaminated Hydraulic Fluid
   • Hydraulic systems are sensitive to contaminants, including dirt, debris, and moisture. If these contaminants enter the fluid, they can cause wear on the system’s internal components, clog filters, and cause erratic behavior in the hydraulics.
     
   • Cause: Contamination can occur through poor maintenance practices, failure to change filters regularly, or damage to seals or hoses that allow external particles to enter the system.
     
3. Faulty Hydraulic Pump
   • The hydraulic pump is the heart of the system, responsible for generating the pressure required for the hydraulic functions. If the pump begins to fail, it can result in a loss of power or erratic performance in the hydraulic system.
     
   • Cause: Overheating, wear, or contamination can cause the pump to fail. In some cases, a worn-out or damaged pump may not be able to generate enough pressure to drive the hydraulic cylinders and valves.
     
4. Hydraulic Valve Malfunctions
   • The hydraulic control valves direct the flow of fluid to various parts of the dozer. A malfunctioning valve can cause hydraulic failure by preventing fluid from reaching the proper areas or by causing an imbalance in the system’s pressure.
     
   • Cause: A valve may become stuck, blocked, or worn out over time, leading to improper fluid distribution and loss of hydraulic power.
     
5. Clogged Hydraulic Filters
   • The filters in the hydraulic system are designed to remove contaminants from the fluid before it circulates through the components. If the filters become clogged, it can restrict fluid flow, leading to a loss of hydraulic pressure and poor performance.
     
   • Cause: Failure to regularly check and replace the hydraulic filters can lead to clogging. Additionally, contamination from external sources can contribute to faster filter wear.
     
6. Damaged Hydraulic Hoses or Leaks
   • Hydraulic hoses are used to transport fluid under high pressure throughout the system. If a hose becomes damaged or develops a leak, it can result in a loss of fluid and reduced hydraulic pressure.
     
   • Cause: Hose wear and tear, exposure to extreme temperatures, or physical damage from debris can all lead to leaks or ruptures in the hoses.
     

Troubleshooting the Loss of Hydraulics
When experiencing a loss of hydraulics, it’s essential to take a systematic approach to troubleshoot the issue. Here’s a step-by-step guide to diagnosing and addressing hydraulic problems:

1. Check Fluid Levels
   • The first step is to check the hydraulic fluid levels. Low fluid is one of the most common causes of hydraulic loss. If the fluid is low, top it off with the recommended fluid type.
     
   • Action: If the fluid is low, check for visible leaks around the system. If you notice a drop in fluid levels over time, inspect hoses, cylinders, and seals for leaks.
     
2. Inspect the Fluid for Contaminants
   • Examine the hydraulic fluid for any signs of contamination. If the fluid is dirty or appears to have metal shavings or particles floating in it, the system is likely experiencing internal wear.
     
   • Action: Drain and replace the contaminated fluid, and replace the filters. Clean or replace the components that may have been damaged by contamination, such as pumps or valves.
     
3. Test the Hydraulic Pump
   • If the fluid is clean and at the proper level, but the hydraulics still aren’t functioning, the next step is to test the hydraulic pump. A weak or failing pump may not generate enough pressure for the system to operate effectively.
     
   • Action: Check the pump’s output pressure using a hydraulic pressure gauge. If the pressure is too low, the pump may need to be repaired or replaced.
     
4. Examine Hydraulic Control Valves
   • If the pump appears to be working correctly, but the hydraulics are still malfunctioning, inspect the control valves. A stuck or blocked valve could be preventing the proper flow of hydraulic fluid.
     
   • Action: Test the valves by operating the machine in various modes. If one valve does not respond as expected, clean or replace the valve. In some cases, the valve’s seals may need to be replaced to restore functionality.
     
5. Check the Hydraulic Filters
   • Inspect the hydraulic filters for signs of clogging or wear. A clogged filter will prevent fluid from circulating properly, reducing the system's overall efficiency.
     
   • Action: Replace any clogged or dirty filters, and make sure to use the proper type of filter recommended by the manufacturer.
     
6. Inspect the Hydraulic Hoses and Fittings
   • Check all hydraulic hoses for signs of damage or wear. A ruptured or leaking hose can cause fluid loss and hydraulic failure. Look for areas where the hoses may be rubbing against other surfaces or exposed to excessive heat.
     
   • Action: Replace any damaged hoses or fittings, and ensure that all connections are tight and leak-free. It’s also advisable to check for any potential sources of friction that could cause future damage to the hoses.
     

Preventive Measures and Maintenance Tips
To avoid hydraulic system failures in the future, regular maintenance and preventive measures are crucial. Here are some tips to keep the Case 850B's hydraulics functioning properly:

1. Routine Fluid Checks: Regularly check hydraulic fluid levels and inspect for contamination. Replace fluid as recommended in the owner's manual to maintain system performance.
   
2. Scheduled Filter Replacements: Replace hydraulic filters at the intervals recommended by the manufacturer. This will help prevent contaminants from damaging the system.
   
3. Inspect Hoses and Seals: Periodically inspect all hydraulic hoses and seals for wear, leaks, or signs of damage. Address any issues promptly to prevent fluid loss.
   
4. Monitor Pump Performance: Keep an eye on the performance of the hydraulic pump. If you notice any decrease in pressure or efficiency, investigate the cause before it leads to a full pump failure.
   
5. Clean System Components: Regularly clean the hydraulic system components to prevent contamination. This includes cleaning the hydraulic tank, valve assemblies, and pump.
   

Conclusion
The hydraulic system is the lifeblood of the Case 850B crawler dozer, and a loss of hydraulics can bring operations to a standstill. By understanding the common causes of hydraulic failure, such as low fluid levels, contamination, pump failure, or faulty valves, operators can quickly identify and resolve issues. Routine maintenance, such as checking fluid levels, replacing filters, and inspecting hoses, can help prevent most hydraulic problems and keep the machine running smoothly for years. A systematic troubleshooting approach is key to minimizing downtime and ensuring the long-term reliability of the Case 850B.