Troubleshooting Case 850B Dozer Brake Issues

[MikePhua]

The Case 850B is a heavy-duty crawler dozer, renowned for its versatility in construction and earth-moving projects. As with any piece of heavy equipment, maintaining its braking system is essential for both safety and optimal operation. However, issues with the braking system can arise over time, particularly in older models or when maintenance is neglected. This article delves into the potential causes of brake problems in the Case 850B, common symptoms to watch for, and effective solutions to restore proper braking performance.
Understanding the Brake System of the Case 850B
The brake system on the Case 850B is designed to provide reliable stopping power and control while operating on various terrains. Typically, dozers like the 850B use a hydraulic braking system, which employs fluid pressure to engage the brakes. This system consists of several components: the master cylinder, brake lines, brake valves, and individual brake assemblies at each wheel or track.
The brake system also includes a parking brake, which is essential for securing the machine when not in use. Over time, these components can experience wear and tear, leading to performance issues. Identifying the root cause of brake problems early can prevent costly repairs and avoid downtime.
Common Causes of Brake Problems in the Case 850B
Brake problems in the Case 850B can stem from various sources. Some of the most common causes include:

1. Low Brake Fluid Levels:
   The hydraulic braking system relies on fluid to generate the necessary pressure to engage the brakes. If the brake fluid levels are low due to leaks or evaporation, the brakes may not engage properly. This can lead to reduced braking efficiency and longer stopping distances.
   
2. Worn Brake Pads or Shoes:
   Over time, the brake pads or shoes on the Case 850B can wear down due to continuous use. As the friction material wears thin, the brake performance diminishes, leading to decreased stopping power. In some cases, the metal backing plate of the pads may begin to rub against the rotor, causing damage to the braking components.
   
3. Contaminated Brake Fluid:
   Contaminants such as dirt, water, or air in the brake fluid can compromise the performance of the braking system. Contaminated fluid may cause the brake fluid to become less effective, leading to spongy pedal feel, poor braking, or complete brake failure. Regular inspection of the brake fluid is essential to ensure its quality.
   
4. Faulty Brake Master Cylinder:
   The brake master cylinder is responsible for generating hydraulic pressure when the operator presses the brake pedal. If the master cylinder becomes damaged or malfunctions, it may not be able to supply sufficient pressure to the brakes, leading to poor braking performance. Signs of a faulty master cylinder include soft or unresponsive brakes.
   
5. Leaking Brake Lines or Seals:
   Brake lines and seals are critical for maintaining pressure within the braking system. Over time, these components can deteriorate, leading to fluid leaks. A leak in the brake lines can result in a loss of pressure, causing the brakes to fail or perform inadequately. Inspecting the brake lines and seals for leaks is essential in preventing this issue.
   
6. Air in the Brake Lines:
   Air trapped in the brake lines can reduce hydraulic pressure and impair braking effectiveness. This can occur when the brake system is not properly bled after maintenance or repairs. When air enters the brake lines, the operator may notice a spongy brake pedal or unresponsive brakes.
   
7. Parking Brake Issues:
   The parking brake in the Case 850B is designed to hold the machine in place when it is not in use. If the parking brake is not fully disengaging or if it is malfunctioning, it can lead to drag or excessive wear on the brake components. Common signs of parking brake issues include a sluggish release or difficulty disengaging the brake.
   

Symptoms of Brake Problems
The following symptoms indicate that the Case 850B’s brake system may be experiencing issues:

• Spongy or Soft Brake Pedal: If the brake pedal feels soft or spongy when pressed, it may indicate air in the brake lines, low brake fluid levels, or a malfunctioning master cylinder.
  
• Reduced Braking Power: If the dozer takes longer to stop or the brakes feel less responsive, it could be due to worn brake pads, low fluid levels, or contamination in the brake fluid.
  
• Brake Fluid Leaks: If you notice brake fluid pooling underneath the machine or find wet spots around the brake lines or master cylinder, this could be a sign of a fluid leak. This often results in reduced braking efficiency.
  
• Unusual Noises: If the brakes produce squealing, grinding, or scraping sounds, it is typically a sign of worn brake pads, dirty brake components, or debris in the brake system.
  
• Sticking or Dragging Parking Brake: If the parking brake fails to disengage properly or causes the machine to drag while operating, it could be due to an issue with the parking brake mechanism or the brake shoes.
  
• Overheating Brakes: If the brakes feel excessively hot after use, it could be an indication that they are not functioning properly, or that they are being overworked due to inadequate maintenance or a mechanical issue.
  

Diagnosing Brake Issues in the Case 850B
To properly diagnose and fix brake problems in the Case 850B, follow these steps:

1. Check Brake Fluid Levels: Begin by checking the brake fluid reservoir. If the fluid levels are low, top them up with the recommended brake fluid. Be sure to check for any leaks in the brake lines or around the master cylinder.
   
2. Inspect Brake Pads and Shoes: If the braking power has diminished, inspect the brake pads or shoes for wear. Measure the thickness of the pads to determine if they need replacing. If the pads are excessively worn, replace them to restore full braking power.
   
3. Look for Fluid Leaks: Inspect the brake lines, hoses, and seals for any signs of leaks. Pay special attention to the connections near the master cylinder, brake valves, and wheel cylinders. Leaks in these areas can lead to a loss of hydraulic pressure and poor braking performance.
   
4. Check for Contaminated Fluid: Drain a small amount of brake fluid and inspect its color and consistency. If the fluid appears dirty, cloudy, or contains debris, flush the brake system and refill with fresh fluid.
   
5. Bleed the Brakes: If air has entered the brake lines, it will need to be purged by bleeding the brakes. Follow the manufacturer’s guidelines for bleeding the brakes to ensure that all air is removed from the system.
   
6. Inspect the Master Cylinder: If the brake pedal feels unusually soft or unresponsive, the master cylinder may need to be replaced or repaired. A damaged master cylinder can cause a loss of hydraulic pressure, leading to poor braking performance.
   
7. Check the Parking Brake: If the parking brake is dragging or not releasing properly, inspect the parking brake mechanism for signs of wear or malfunction. It may need adjustment or repairs to function correctly.
   

Solutions and Repair Options
Once the cause of the brake problem has been identified, the necessary repairs should be carried out as follows:

• Replace Worn Brake Pads or Shoes: If the brake pads or shoes are worn down, replace them with new parts. Always use high-quality replacement components that meet the manufacturer’s specifications.
  
• Repair or Replace the Master Cylinder: If the master cylinder is faulty, it will need to be repaired or replaced. A rebuild kit may be available, or a complete replacement may be necessary if the cylinder is severely damaged.
  
• Fix Leaking Brake Lines or Seals: If a leak is detected, replace the damaged brake lines or seals. Ensure all connections are tightened properly to prevent further leaks.
  
• Flush and Refill Brake Fluid: After fixing leaks or replacing components, flush the brake system to remove any contaminated fluid. Refill with the recommended brake fluid and bleed the system to remove any air.
  
• Adjust or Replace Parking Brake: If the parking brake is dragging, adjust or replace the parking brake components to ensure proper operation.
  

Preventive Maintenance Tips
To avoid brake issues in the future, perform the following preventive maintenance tasks on your Case 850B:

• Regularly check brake fluid levels and inspect for leaks.
  
• Inspect brake pads and shoes for wear and replace them as needed.
  
• Change brake fluid periodically to prevent contamination.
  
• Ensure that the parking brake is functioning correctly and releases fully.
  
• Perform routine inspections of the master cylinder, brake lines, and seals to detect early signs of wear.
  

Conclusion
Brake problems in the Case 850B can be frustrating, but they are often preventable with regular maintenance and prompt attention to any issues. By understanding the common causes of brake failure and taking proactive steps to address them, operators can extend the lifespan of their dozers and maintain optimal performance. Whether it's replacing worn components, fixing leaks, or simply checking fluid levels, proper care of the brake system is essential for the safety and efficiency of the machine.