Diagnosing and Solving the Screeching Noise in Bobcat 843 When Loaded Downhill

[MikePhua]

Introduction
The Bobcat 843 skid steer loader is a rugged, versatile machine used in construction, landscaping, and material handling tasks. However, like any heavy equipment, it is not immune to mechanical issues that can affect its performance and efficiency. One common issue that many operators have reported with the Bobcat 843 is a screeching noise, particularly when the machine is loaded and moving downhill.
Understanding the cause of this screeching noise is essential for preventing further damage to the machine and ensuring safe and efficient operation. In this article, we’ll delve into the potential causes of the screeching noise and explore practical solutions to address the problem.
Common Causes of Screeching Noise in Bobcat 843
When a Bobcat 843 makes a screeching noise while loaded and moving downhill, it’s typically related to the drivetrain, brakes, or other mechanical systems under load. Several factors may contribute to this issue:
1. Worn or Improperly Adjusted Brakes
One of the most common causes of screeching noises during downhill operation is worn-out or improperly adjusted brakes. When the machine is moving downhill with a load, the brakes are put under more stress, which can cause them to make high-pitched squealing or screeching noises.
Solution:

• Inspect the Brake Pads: Check the condition of the brake pads. If the pads are worn down, they may need to be replaced.
  
• Adjust Brake Tension: Ensure that the brake tension is correctly set. Improper tension can lead to unnecessary friction and noise.
  
• Replace Worn Components: If there’s damage or excessive wear on the brake system, replacing the brake shoes or pads might be necessary.
  

2. Misalignment of the Drive Belt
The Bobcat 843’s drive system relies on a belt to transfer power from the engine to the wheels. A misaligned or loose drive belt can cause slippage and friction, which results in a screeching noise. This issue can be exacerbated when the machine is loaded and moving downhill, as more power is required to maintain control.
Solution:

• Check Belt Tension and Alignment: Inspect the drive belt for proper tension and alignment. If the belt is loose or misaligned, it should be adjusted or replaced.
  
• Inspect the Pulley System: Ensure that the pulleys are in good condition and free from debris or wear that could cause uneven belt tension.
  

3. Overloaded Machine
When operating a Bobcat 843 with a heavy load, the machine’s components may be under increased strain, particularly when moving downhill. Overloading the machine can cause additional friction and stress on the drivetrain, brakes, and other mechanical parts, leading to unusual noises like screeching.
Solution:

• Reduce Load Weight: Ensure that the machine is not carrying more than its recommended load capacity. Overloading not only leads to screeching noises but can also cause long-term damage to the machine’s components.
  
• Check Load Distribution: Make sure the load is evenly distributed. Uneven weight distribution can cause strain on specific parts of the machine, leading to screeching and potential damage.
  

4. Low Hydraulic Fluid or Pressure
The Bobcat 843’s hydraulic system powers many of the machine’s key functions, including the movement of the lift arms and the operation of attachments. If the hydraulic fluid is low or the pressure is inadequate, the machine may experience jerky movements, which can lead to screeching noises. The issue could become more pronounced when the machine is under load, such as when moving downhill.
Solution:

• Check Hydraulic Fluid Levels: Ensure that the hydraulic fluid is at the proper level. If it's low, top it off with the recommended fluid type.
  
• Inspect the Hydraulic System: Look for any signs of leaks or damage in the hydraulic hoses and components. If any issues are found, the hydraulic system may need to be repaired or replaced.
  
• Test Hydraulic Pressure: If the fluid levels are fine, but the issue persists, check the hydraulic pressure. Low pressure may indicate a problem with the pump or valves, which may require professional inspection and repair.
  

5. Worn or Damaged Wheel Bearings
The Bobcat 843 uses wheel bearings to ensure smooth rotation of the wheels. Over time, these bearings can wear out or become damaged, causing friction and noise when the wheels rotate. The noise may become more noticeable when the machine is loaded, especially when moving downhill, as additional stress is placed on the bearings.
Solution:

• Inspect the Wheel Bearings: Check the wheel bearings for signs of wear or damage, such as rough rotation or play in the wheels.
  
• Replace Worn Bearings: If the bearings are worn or damaged, they will need to be replaced to restore smooth wheel operation and eliminate the screeching noise.
  

6. Insufficient Lubrication in the Drivetrain
A lack of proper lubrication in the drivetrain can cause components like the axles, bearings, and gears to generate friction and produce screeching or grinding noises. This issue can worsen when the machine is loaded or moving downhill, as the drivetrain is under greater strain.
Solution:

• Lubricate Drivetrain Components: Ensure that all moving parts in the drivetrain are properly lubricated. Follow the manufacturer’s maintenance schedule for lubrication and use the recommended lubricants.
  
• Check for Leaks: Inspect the drivetrain for any signs of leaks that could cause a loss of lubrication. Address any issues by replacing seals or gaskets as necessary.
  

Steps to Diagnose and Fix Screeching Noise
If you are experiencing a screeching noise in your Bobcat 843 while moving downhill with a load, here’s how you can go about diagnosing and fixing the problem:

1. Check for Visible Damage: Start by performing a visual inspection of the machine’s key components, such as the brakes, drive system, and hydraulic system.
   
2. Test the Brake System: Engage the brakes while stationary to listen for any abnormal sounds. If there is a squealing or screeching noise, inspect the brake pads and adjust the brake tension.
   
3. Inspect the Drive Belt: Check the condition of the drive belt for wear or misalignment. Adjust or replace the belt as necessary.
   
4. Check Load Weight: Verify that the machine is not overloaded, and adjust the load as needed to avoid unnecessary strain on the system.
   
5. Inspect the Hydraulic System: Check the hydraulic fluid levels and pressure. If low, add the appropriate fluid, and inspect for leaks or damage.
   
6. Check Wheel Bearings: Inspect the wheel bearings for wear or damage. Replace any faulty bearings.
   
7. Lubricate Drivetrain Components: Ensure that the drivetrain is properly lubricated, including the axles and bearings.
   

Conclusion
A screeching noise from the Bobcat 843 when loaded and moving downhill can be caused by various factors, from worn brake pads to issues with the drive system or hydraulic components. By following a systematic approach to diagnosing the problem, operators can identify the source of the noise and take the necessary steps to resolve it. Regular maintenance and inspections are key to keeping your Bobcat 843 running smoothly and avoiding further issues down the road.
Taking care of these common mechanical issues will not only help maintain the machine’s performance but also ensure a safer, more efficient operation. If the issue persists despite these measures, it’s advisable to consult with a professional technician to perform a more thorough inspection and repair.