Ford 555A Backhoe Auxiliary Hydraulics Explained

[MikePhua]

The Legacy of the Ford 555A Backhoe
The Ford 555A backhoe loader, introduced in the mid-1980s, marked a significant evolution in Ford’s construction equipment lineup. Built during a time when Ford was expanding its industrial machinery division, the 555A combined rugged mechanical design with hydraulic versatility. Manufactured in Highland Park, Michigan, the 555A was part of a broader push to compete with established players like Case and John Deere in the compact construction market.
With a gross operating weight of approximately 13,000 pounds and a 60-horsepower diesel engine, the 555A was widely adopted across North America for utility work, trenching, and small-scale excavation. Over its production run, Ford sold tens of thousands of units, many of which remain in service today due to their mechanical simplicity and robust build.
Terminology Annotation

• Auxiliary Hydraulics: Additional hydraulic circuits used to power attachments beyond the standard loader and backhoe functions.
  
• V60 Valve: A compact hydraulic control valve designed to regulate flow and pressure for auxiliary tools.
  
• Solenoid: An electromechanical device that controls fluid flow by energizing a magnetic coil.
  
• Relief Valve: A safety component that limits hydraulic pressure to prevent system damage.
  

Understanding the Auxiliary Hydraulic Setup
The auxiliary hydraulic system on the Ford 555A was often installed as part of a dealer-approved kit, particularly when the machine was outfitted with a hydraulic breaker or similar attachment. One common configuration included the Stanley V60 valve—a compact unit capable of handling up to 60 gallons per minute (gpm) of flow and pressures up to 5,000 psi. The regulated output was typically capped at 34 gpm, with adjustable relief settings ranging from 250 to 3,000 psi.
This valve was usually mounted inside the right-hand frame rail near the hydraulic filter. It featured three primary lines:

• Pressure Inlet: From the main hydraulic pump
  
• Regulated Outlet: To the auxiliary tool
  
• Return Line: Back to tank or reservoir
  

A small fourth line may have been added for tank drainage or pilot control. The valve was actuated via a solenoid, which received power through a simple wiring harness connected to a foot pedal. When the pedal was pressed, the solenoid energized, redirecting flow to the auxiliary port.
Troubleshooting Common Issues
Operators often encounter problems where the auxiliary system fails to activate—no power to the switch, no flow to the ports. These symptoms usually point to electrical faults or valve misbehavior. A structured diagnostic approach includes:

• Check Fuse and Power Supply: Ensure the hot wire feeding the foot switch is live and properly fused.
  
• Inspect Solenoid Wiring: Look for corrosion, loose terminals, or broken wires between the switch and solenoid.
  
• Test Solenoid Function: Use a multimeter to verify coil resistance and continuity.
  
• Manually Activate Valve: If safe, manually shift the valve to confirm mechanical operation.
  
• Verify Relief Settings: Ensure the valve is not bypassing flow due to low pressure thresholds.
  

In one real-world case, a contractor in Ohio discovered that a broken wire under the floorboard had disabled the entire auxiliary system. After replacing the wire and cleaning the solenoid terminals, the hydraulic breaker resumed normal operation.
Stanley Hydraulic Breaker Integration
The Stanley hydraulic hammer, often paired with the 555A, required consistent regulated flow and pressure. These tools typically only fire when downward pressure is applied to the tool bit, a safety feature that prevents accidental activation. The V60 valve was specifically designed to accommodate this behavior, ensuring that flow was only directed to the hammer when the solenoid was energized and the operator applied force.
Stanley, founded in the early 20th century and later merged into Stanley Black & Decker, became a leading supplier of hydraulic tools for construction and demolition. Their V-series valves were widely adopted across OEM platforms due to their compact size and reliability.
Improving System Reliability
To enhance the performance and longevity of the auxiliary hydraulic system on the Ford 555A, consider the following upgrades:

• Install Weatherproof Connectors: Protect electrical connections from moisture and debris.
  
• Add Indicator Lights: Visual confirmation of solenoid activation can simplify troubleshooting.
  
• Use Quick-Connect Couplers: Streamline attachment changes and reduce contamination risk.
  
• Flush Hydraulic Lines Regularly: Prevent buildup of sludge or particulates that can clog valves.
  
• Upgrade to Modern Valves: Replace aging V60 units with newer proportional control valves for smoother operation.
  

Historical Anecdote and Industry Impact
In 1987, a municipal crew in North Carolina retrofitted their fleet of Ford 555A backhoes with auxiliary hydraulic kits to support trenching and demolition tasks. The upgrade allowed them to use hydraulic hammers and compactors, reducing manual labor and improving project timelines. Over the next five years, the city reported a 25% increase in productivity and a 40% reduction in equipment downtime.
This success story contributed to broader adoption of auxiliary hydraulics in municipal fleets, influencing procurement standards and training programs nationwide.
Conclusion
The auxiliary hydraulic system on the Ford 555A backhoe represents a blend of mechanical ingenuity and aftermarket adaptability. With the right components—such as the Stanley V60 valve—and proper electrical integration, operators can unlock powerful capabilities for attachments like hammers and compactors. While documentation may be sparse, a methodical approach to diagnostics and upgrades ensures that these legacy machines continue to perform reliably in modern job sites.