Diagnosing and Resolving Jerky Steering in Bobcat 873F Skid Steer Loaders

[MikePhua]

Introduction
The Bobcat 873F Skid Steer Loader is renowned for its versatility and power, making it a staple in various construction and landscaping projects. However, operators have reported issues with jerky or erratic steering, especially during low-speed maneuvers. Understanding the underlying causes and implementing appropriate solutions is crucial for maintaining optimal performance and safety.
Common Causes of Jerky Steering

1. Worn or Loose Linkage Components
   The steering system of the 873F relies on a series of linkages that connect the steering levers to the hydrostatic pumps. Over time, components such as the pintle arm, which connects to the pump control shaft, can become loose or worn. This wear can lead to delayed or erratic steering responses, often described as "bucking" or "jerking" movements.
   
2. Hydraulic System Issues
   The 873F's hydrostatic drive system is sensitive to hydraulic fluid quality and pressure. Low or contaminated hydraulic fluid can cause erratic steering behavior. Additionally, issues with the steering servos or the main pump can lead to inconsistent steering responses.
   
3. Steering Control Valve Problems
   The steering control valve regulates the flow of hydraulic fluid to the steering cylinders. If this valve becomes clogged or damaged, it can result in jerky or unresponsive steering. Regular maintenance and inspection of the steering control valve are essential to ensure smooth operation.
   

Diagnostic Steps

1. Inspect Linkage Components
   Begin by raising the loader's cab and inspecting the steering linkages for any signs of wear or looseness. Pay particular attention to the pintle arm and its connection to the pump control shaft. If any components are found to be worn or loose, they should be replaced or tightened as necessary.
   
2. Check Hydraulic Fluid Levels and Quality
   Ensure that the hydraulic fluid is at the proper level and is free from contaminants. If the fluid appears dirty or has a burnt smell, it should be replaced. Also, check for any leaks in the hydraulic system that could affect steering performance.
   
3. Test Steering Control Valve
   Operate the steering levers and observe the response of the steering cylinders. If the steering is unresponsive or jerky, the steering control valve may need to be cleaned or replaced.
   

Maintenance Tips

• Regularly Inspect Linkages
  Routine inspections of the steering linkages can help identify wear or looseness before they lead to steering issues. Replace any worn components promptly to maintain smooth steering.
  
• Use High-Quality Hydraulic Fluid
  Always use the manufacturer's recommended hydraulic fluid and change it at the intervals specified in the owner's manual. This practice helps prevent contamination and ensures optimal hydraulic system performance.
  
• Keep the Steering Control Valve Clean
  Regularly clean the steering control valve to prevent debris buildup that can affect steering performance. If the valve becomes damaged, replace it promptly to avoid steering issues.
  

Case Study: Addressing Jerky Steering in a Bobcat 873F
In a real-world scenario, a Bobcat 873F owner reported experiencing jerky steering movements when attempting to creep forward. Upon inspection, the pintle arm was found to be loose, causing delayed steering responses. After tightening the pintle arm and replacing worn linkage components, the steering became smooth and responsive, resolving the issue.
Conclusion
Jerky steering in the Bobcat 873F Skid Steer Loader can stem from various issues, including worn linkage components, hydraulic system problems, and steering control valve malfunctions. By conducting thorough diagnostics and adhering to regular maintenance practices, operators can ensure smooth and responsive steering, enhancing safety and efficiency on the job site.