Troubleshooting the Articulation Valve on a Champion 730A Motor Grader

[MikePhua]

Intermittent Steering and Solenoid Failure
The Champion 730A motor grader, a mid-size machine known for its reliability in municipal and forestry road maintenance, uses a hydraulically actuated articulation system controlled by solenoid valves. In one case, the articulation valve began functioning intermittently—first failing in one direction, then ceasing entirely. The operator had recently installed new solenoids, suggesting the issue lay deeper within the valve body or spool assembly.
Terminology Clarification

• Articulation Valve: A hydraulic control valve that manages the pivoting motion of the grader’s frame, allowing tighter turns and improved maneuverability.
  
• Solenoid: An electromechanical actuator that opens or closes hydraulic passages when energized.
  
• Spool: A cylindrical internal component that shifts within the valve body to direct fluid flow.
  
• Manual Override: A mechanical method to actuate the valve without electrical input, used for diagnostics or emergency operation.
  

Likely Causes and Diagnostic Strategy
The symptoms point to either a stuck spool or a jammed solenoid plunger. Hydraulic valves are precision components, and even microscopic contamination can prevent proper movement. The operator planned to engage the manual override to cycle the spool and potentially free it. This is a valid approach—cycling the spool manually can sometimes dislodge debris or re-seat a misaligned plunger.
Before disassembly, technicians should:

• Check voltage at the solenoid terminals to confirm electrical continuity.
  
• Inspect the solenoid coil for heat damage or corrosion.
  
• Remove the solenoid and test plunger movement manually.
  
• Engage the manual override and observe spool response.
  

Cleaning and Reassembly Recommendations
When disassembling the valve:

• Use lint-free cloths and clean hydraulic fluid to wipe components.
  
• Avoid aggressive solvents unless specified by the manufacturer. Contact cleaner may be safe for electrical parts but not for seals or anodized surfaces.
  
• Replace all o-rings with OEM-grade Viton or Buna-N equivalents.
  
• Inspect the spool for scoring, burrs, or varnish buildup.
  

A technician noted that even a single grain of sand or degraded seal fragment can cause the spool to hang. Cleaning must be meticulous, and reassembly should be done in a dust-free environment.
Champion’s Legacy and Parts Support
Champion motor graders were manufactured in Goderich, Ontario, and gained popularity across North America for their mechanical simplicity and robust frames. The 730A was part of the articulated series introduced in the 1980s, featuring hydraulic steering and improved operator ergonomics. After Champion was acquired by Volvo in the late 1990s, parts support transitioned to Volvo Construction Equipment, though many independent suppliers still stock components for legacy models.
Preventive Measures and Long-Term Advice

• Install inline hydraulic filters rated at 10 microns to reduce contamination.
  
• Flush the hydraulic system every 2,000 hours or annually, whichever comes first.
  
• Use synthetic hydraulic fluid with anti-wear additives for better spool lubrication.
  
• Label solenoid wires clearly to avoid misconnection during maintenance.
  
• Keep a printed valve schematic in the cab for troubleshooting.
  

Conclusion
Articulation valve issues on the Champion 730A are often caused by contamination or mechanical sticking within the spool or solenoid assembly. With careful diagnostics, manual override testing, and thorough cleaning, the valve can often be restored without full replacement. This case underscores the importance of clean hydraulic practices and the enduring serviceability of Champion’s grader design.