Gehl 6640 Hydraulics Disengaged Issue

[MikePhua]

Overview of the Gehl 6640 Skid Steer
The Gehl 6640 is a compact skid steer loader designed for high productivity in tight spaces. Popular in construction, landscaping, and demolition, the Gehl 6640 features a robust hydraulic system that powers the lifting arms, auxiliary hydraulics, and various attachments. Like most skid steers, it is equipped with a hydraulic drive system that facilitates quick, powerful movements for heavy lifting and digging tasks. However, when the hydraulics disengage or fail to operate properly, it can cause significant downtime and disrupt operations.
Understanding the Hydraulic System in Skid Steers
A skid steer like the Gehl 6640 relies on hydraulic power to operate its arms, lift and tilt attachments, and power auxiliary hydraulics for specialized tools. The hydraulic system consists of a hydraulic pump, motor, fluid, and a series of hoses and valves that control the flow of fluid throughout the machine.
When the hydraulic system is engaged, fluid is pressurized by the pump and sent to the cylinders, which then move the loader arms or attachments. The efficiency of this system is crucial for the loader’s performance, as it powers the machine’s key functions, including the lifting, lowering, and tilting movements.
Common Causes of Hydraulic Disengagement
The disengagement of hydraulics in a Gehl 6640 can be caused by several issues, all of which need to be addressed to restore normal operation. Common causes of hydraulic disengagement include:

1. Low Hydraulic Fluid Level: The most straightforward issue is low hydraulic fluid. If the fluid level is too low, the pump cannot pressurize the fluid effectively, leading to sluggish or disengaged hydraulics. This can happen if there is a leak or the fluid hasn’t been replenished during maintenance.
   
2. Hydraulic Fluid Contamination: Contaminants such as dirt, debris, or moisture can compromise the performance of the hydraulic system. When contaminants enter the system, they can cause blockages, increase wear on components, or reduce the fluid's ability to flow smoothly through the system.
   
3. Faulty Hydraulic Pump: A failing hydraulic pump can cause a lack of fluid pressure, leading to disengaged hydraulics. Over time, pumps can wear out due to extended use or lack of proper maintenance, which leads to performance issues.
   
4. Clogged or Blocked Hydraulic Filters: Hydraulic filters are designed to remove debris from the fluid before it circulates through the system. If the filter becomes clogged, it can cause a reduction in fluid flow, which may disengage hydraulic functions.
   
5. Damaged or Leaking Hoses and Fittings: Leaks in the hydraulic lines, fittings, or seals can reduce the overall pressure in the system, leading to a lack of power and disengagement of hydraulic functions.
   
6. Electrical or Control Valve Issues: The hydraulic system in the Gehl 6640 may also rely on electronically controlled valves. If these valves malfunction due to electrical faults, control issues, or worn parts, the hydraulics may fail to engage or disengage properly.
   

Troubleshooting Hydraulic Disengagement
When hydraulics fail to engage or disengage properly, the following steps can help identify and resolve the issue:

1. Check Fluid Levels: Begin by inspecting the hydraulic fluid level. Ensure it is within the recommended range and top it off if necessary. Low fluid levels are the most common cause of disengagement, so this is the first thing to verify.
   
2. Inspect Hydraulic Fluid for Contamination: If the fluid appears cloudy or contaminated with debris, it should be replaced. Contaminated fluid can damage the pump, valves, and other components, so ensuring clean fluid is essential for optimal performance.
   
3. Examine Filters for Blockages: Inspect the hydraulic filters for blockages. If they are clogged, clean or replace the filters as needed. A clogged filter restricts fluid flow and can lead to poor hydraulic performance.
   
4. Check for Leaks: Inspect the hydraulic lines, hoses, and fittings for any signs of leaks or wear. If any parts are leaking, they will need to be repaired or replaced to restore proper fluid pressure.
   
5. Test the Hydraulic Pump: If the fluid levels and hoses are in good condition, but the hydraulics still fail to engage, the pump may be the issue. A diagnostic test can help determine if the pump is producing enough pressure. If the pump is malfunctioning, it may need to be repaired or replaced.
   
6. Inspect Control Valves and Wiring: If the pump and fluid system are functioning properly, the issue could lie with the control valves or wiring. Ensure that the control system is responsive and there are no electrical faults preventing the system from functioning.
   

Preventative Maintenance for the Hydraulic System
To prevent hydraulic disengagement issues from occurring in the future, consider the following maintenance tips:

1. Regular Fluid Checks: Periodically check the hydraulic fluid level and top it off as needed. Keeping the fluid at the recommended level helps maintain consistent pressure in the system.
   
2. Replace Filters on Schedule: Replace the hydraulic filters as per the manufacturer’s recommendations to ensure clean fluid and prevent contamination.
   
3. Inspect Hydraulic Hoses and Fittings: Regularly inspect the hoses and fittings for any signs of wear or leaks. Replacing damaged hoses early can prevent more severe hydraulic issues down the line.
   
4. Change Fluid at Recommended Intervals: Follow the manufacturer’s guidelines for changing the hydraulic fluid to prevent buildup of contaminants that could degrade system performance.
   
5. Monitor Pump and Valve Performance: Have the hydraulic pump and control valves inspected regularly by a professional to ensure they are functioning optimally.
   

Conclusion
Hydraulic disengagement in the Gehl 6640 can be caused by a variety of issues, from low fluid levels and contaminated fluid to pump malfunctions or control valve issues. Identifying the root cause of the problem is essential to restoring the machine’s performance and preventing further damage. Regular maintenance, including fluid checks, filter replacements, and hose inspections, can help ensure that the hydraulic system operates smoothly and efficiently. By staying on top of these tasks, operators can extend the lifespan of their equipment and avoid costly downtime.