Lull 644B-42 Low Steering Pressure Troubleshooting and Solutions

[MikePhua]

The Lull 644B-42 is a commonly used telehandler for construction and material handling tasks. Some users report experiencing low steering pressure while operating the machine, which can affect the steering performance, making it harder to maneuver or control the machine. This issue is typically related to hydraulic system malfunctions, steering pump problems, or hydraulic oil conditions. Addressing the problem requires identifying the root cause, which can range from low hydraulic oil levels to pump failures.
Common Causes of Low Steering Pressure

1. Low Hydraulic Oil Level
   A low hydraulic oil level is one of the most common causes of low steering pressure. If the hydraulic oil is insufficient, the steering pump won't generate the required pressure, resulting in poor steering performance.
   Solution:
   • Check the hydraulic oil level to ensure it's within the recommended range.
     
   • If the oil is low, top it up with the correct type of hydraulic oil as per the manufacturer’s specifications.
     
   • Inspect the oil quality and ensure there are no contaminants.
     
2. Hydraulic Pump Failure
   A malfunctioning hydraulic pump may also cause low steering pressure. If the hydraulic pump is damaged or worn, it may fail to generate the necessary flow of hydraulic fluid, resulting in low pressure.
   Solution:
   • Inspect the hydraulic pump to ensure it is functioning properly.
     
   • If the pump is making unusual noises or leaking, it may need to be replaced.
     
   • Check for blockages in the pump's inlet and outlet lines.
     
3. Hydraulic Line Leaks
   Leaks in the hydraulic system can cause a loss of hydraulic fluid, resulting in low pressure. Leaks often occur at connection points or in damaged hoses.
   Solution:
   • Check all hydraulic hoses and connections for leaks.
     
   • If leaks are found, repair or replace the damaged hoses or seals immediately.
     
   • Ensure all hydraulic connections are properly tightened to avoid loose fittings.
     
4. Hydraulic Valve Malfunction
   A malfunctioning hydraulic valve can also cause low steering pressure. If the valve is stuck or damaged, it may not properly regulate the flow and pressure of hydraulic fluid.
   Solution:
   • Inspect the hydraulic valve for blockages or damage.
     
   • Clean the valve to ensure it's free from debris.
     
   • If the valve is damaged, replace it as needed.
     
5. Steering Cylinder Issues
   Leaking or damaged seals in the steering cylinder can cause hydraulic fluid to bypass, reducing the pressure needed for steering.
   Solution:
   • Inspect the steering cylinder for leaks or damaged seals.
     
   • If leaks are present, replace the seals or repair the cylinder.
     

Troubleshooting Steps

1. Check Hydraulic Oil Level
   Start by checking the hydraulic oil level. Ensure the oil is at the correct level and is free from contamination. If necessary, top up the oil with the appropriate type.
   
2. Inspect the Hydraulic Pump
   If the hydraulic oil level is sufficient, check the hydraulic pump's operation. Look for signs of malfunction, such as unusual noise or leaks. If the pump is faulty, it may need to be repaired or replaced.
   
3. Examine Hydraulic Lines for Leaks
   Inspect all hydraulic lines and connections for leaks. Any signs of fluid loss should be addressed immediately by replacing damaged hoses or seals.
   
4. Check Hydraulic Valve Operation
   Inspect the hydraulic valve to ensure it's working as expected. If the valve is clogged or malfunctioning, clean or replace it.
   
5. Inspect the Steering Cylinder
   Finally, check the steering cylinder for leaks or damaged seals. If the cylinder is faulty, it may need to be repaired or replaced.
   

Conclusion
Low steering pressure in the Lull 644B-42 is usually caused by issues in the hydraulic system, such as low hydraulic oil, pump failure, hydraulic line leaks, valve malfunctions, or steering cylinder problems. By systematically checking the hydraulic oil, pump, lines, valves, and steering cylinder, you can quickly pinpoint and address the issue. Regular maintenance and inspection of these components are key to ensuring optimal performance and preventing future problems.