Bobcat S185 Intermittent Park Brake Locking Up: Diagnosis and Troubleshooting

[MikePhua]

Introduction to the Issue
The Bobcat S185, a popular skid steer loader, is known for its power, versatility, and reliability in construction and landscaping jobs. However, like all heavy equipment, it is not without its share of issues. One common problem faced by operators is the intermittent locking up of the park brake. When this happens, it can cause the machine to become immobilized or the park brake to engage unexpectedly during operation.
In this article, we will discuss the potential causes of an intermittent park brake locking up on the Bobcat S185, how to troubleshoot the issue, and what steps can be taken to resolve the problem. Understanding the mechanics behind this problem and how to address it will help you ensure that your equipment continues to perform optimally.
How the Park Brake System Works on the Bobcat S185
The Bobcat S185 is equipped with a hydraulic park brake system. This system is responsible for keeping the machine stationary when not in operation. When the machine is in a parked position, the hydraulic system engages the brake by applying pressure to the brake disc, effectively locking the wheels.
The park brake system is designed to disengage automatically when the engine is running and when the operator moves the control levers. However, when there is an issue within the system, such as with the hydraulic pressure or mechanical components, the park brake can become engaged or lock up intermittently.
Common Causes of Park Brake Locking Up
Several factors can cause the park brake to lock up intermittently on the Bobcat S185. Let’s take a look at some of the most common causes:

1. Hydraulic Pressure Issues
   

The park brake on the Bobcat S185 is hydraulically operated, meaning that the brake system relies on the machine's hydraulic pressure to function correctly. If the hydraulic system experiences issues such as low fluid levels, a faulty hydraulic pump, or a blocked hydraulic line, it can result in inconsistent pressure, which may cause the park brake to engage or lock up unexpectedly.

• Low Hydraulic Fluid: Low hydraulic fluid levels can lead to insufficient pressure, which might cause the park brake to engage or remain locked when it shouldn’t.
  
• Hydraulic Leaks: Leaks in the hydraulic lines or fittings can result in a loss of pressure, preventing the brake from disengaging properly.
  
• Faulty Hydraulic Pump: A malfunctioning hydraulic pump can affect the entire hydraulic system, including the park brake mechanism. If the pump isn’t delivering consistent pressure, the brake could lock up intermittently.
  

1. Electrical or Solenoid Malfunction
   

The park brake system on the Bobcat S185 also relies on electrical components, such as a solenoid or electrical actuator, to engage and disengage the brake. If there is a problem with the solenoid, such as a wiring issue or electrical short, the park brake may lock up unexpectedly.

• Solenoid Failure: A faulty solenoid can cause the park brake to remain engaged, even when it should be disengaged, or prevent it from engaging at all.
  
• Wiring Issues: Damaged wiring or poor connections can prevent the solenoid from receiving the correct signals, causing the brake to lock up intermittently.
  

1. Control Lever or Linkage Issues
   

The park brake system is connected to the machine’s control lever. If the lever or linkage components are worn or misaligned, they may not properly signal the park brake system to disengage when needed. This can cause the park brake to remain engaged even when the machine is in operation.

• Worn Linkages: Over time, the linkages that control the park brake can wear out or become loose. This can prevent the system from disengaging correctly, causing intermittent lock-ups.
  
• Control Lever Misalignment: If the control lever is out of alignment, it may not fully disengage the park brake system, resulting in the brake locking up intermittently.
  

1. Brake Component Wear or Damage
   

Another potential cause for the intermittent locking of the park brake could be worn or damaged brake components. If the brake discs, calipers, or other internal parts are worn out or damaged, they may not function properly, leading to locking or engaging at inopportune times.

• Worn Brake Pads: Worn brake pads or discs can cause the park brake to malfunction, leading to intermittent locking.
  
• Corroded or Damaged Components: Rust, corrosion, or physical damage to the brake components can prevent them from disengaging smoothly, causing the brake to lock up.
  

Troubleshooting the Intermittent Park Brake Locking Up
If you’re experiencing intermittent park brake locking on your Bobcat S185, the following troubleshooting steps can help you identify and resolve the issue:

1. Check Hydraulic Fluid Levels
   

The first step in troubleshooting this issue is to inspect the hydraulic fluid levels. If the fluid is low, top it off with the recommended hydraulic fluid. It’s also important to check for any signs of leaks in the hydraulic lines or fittings. If there are any visible leaks, these will need to be repaired to restore proper hydraulic pressure.

1. Test the Hydraulic System
   

If the fluid levels are adequate, the next step is to test the hydraulic pump and lines. Look for any signs of damage, wear, or blockages in the system. A malfunctioning hydraulic pump can cause erratic pressure, leading to issues with the park brake.

1. Inspect the Solenoid and Electrical Connections
   

Next, check the solenoid and the electrical wiring that controls the park brake system. Ensure that the wiring is intact and properly connected. If the solenoid is faulty, it may need to be replaced. Testing the electrical components with a multimeter can help identify any electrical issues.

1. Examine the Control Lever and Linkages
   

Inspect the control lever and the linkage components for signs of wear or misalignment. Tighten or replace any worn linkages, and ensure that the control lever is correctly aligned and functioning smoothly.

1. Inspect Brake Components
   

Finally, inspect the brake components themselves. Look for signs of wear on the brake pads or discs. If any components are damaged, they may need to be replaced to restore the park brake’s proper functionality.
Preventative Maintenance Tips
To prevent future park brake issues on the Bobcat S185, consider the following maintenance tips:

• Regularly Check Hydraulic Fluid: Make it a habit to check the hydraulic fluid levels regularly. This ensures that the park brake system is receiving the necessary pressure to operate correctly.
  
• Lubricate the Linkages: Periodically lubricate the control lever and linkages to reduce wear and ensure smooth operation.
  
• Inspect Electrical Connections: Regularly inspect the wiring and electrical connections for signs of damage or wear. This can help prevent electrical issues from affecting the park brake system.
  
• Replace Worn Brake Components: Regularly check the brake pads, discs, and other components for wear and replace them as needed.
  

Conclusion
The intermittent locking of the park brake on the Bobcat S185 can be caused by a variety of issues, including hydraulic pressure problems, electrical malfunctions, control lever misalignment, or brake component wear. By following the troubleshooting steps outlined above and performing regular maintenance on the machine, you can keep your park brake system functioning properly and prevent future issues.
As with any heavy equipment problem, early detection and proactive maintenance are key to ensuring that your Bobcat S185 continues to operate efficiently and safely on the job site.