Grove RT-60S Outrigger Failure Often Caused by Solenoid Coil or Electrical Connection Issues

[MikePhua]

Grove RT-60S Crane Overview
The Grove RT-60S is a rough terrain hydraulic crane designed for heavy lifting in construction, industrial, and utility applications. Manufactured by Grove, a brand under Manitowoc Company, the RT-60S features a four-wheel drive chassis, telescoping boom, and hydraulic outriggers for stability during lifts. Grove has been producing mobile cranes since the 1940s, and the RT series is known for its durability and off-road capability. The RT-60S, with a lifting capacity of approximately 60 tons, is commonly deployed in remote or uneven terrain where conventional truck cranes cannot operate.
Outrigger System and Common Failure Points
Outriggers are hydraulic stabilizers that extend and lower to provide a wide base of support during crane operation. Each outrigger leg is controlled by a solenoid valve that directs hydraulic fluid to extend or retract the cylinder. When one outrigger fails to deploy, the issue is typically electrical or hydraulic in nature.
In the case of the RT-60S, a rear outrigger that refuses to go down—while still moving laterally—suggests that the extend function is not receiving hydraulic pressure. This is often due to:

• Faulty solenoid coil: The coil may lose continuity due to internal wire breakage or corrosion.
  
• Broken spade terminal: The electrical connection at the solenoid may be physically damaged or disconnected.
  
• Failed relay or fuse: The control circuit may be interrupted upstream.
  
• Wiring harness corrosion: Especially common in older units exposed to moisture or road salt.
  
• Valve spool obstruction: Debris or wear may prevent the spool from shifting to the extend position.
  

Diagnostic Procedure and Repair Strategy
To diagnose the issue:

• Turn the key to the “on” position with the engine off.
  
• Have a second person activate the outrigger control while using a voltmeter or test light at the solenoid terminals.
  
• If no voltage is present, trace the wire back to the relay or cab switch.
  
• If voltage is present but the solenoid does not actuate, remove the coil and inspect for continuity.
  
• If the coil is damaged, replace it with a compatible unit—often manufactured by Parker, not proprietary to Grove.
  

One technician discovered that the ground spade had broken off inside the molded plastic of the coil. By carefully cutting away the plastic and splicing a new terminal, he restored function without replacing the entire valve assembly.
Additional Field Tips and Preventive Measures

• Always carry spare solenoid coils and spade terminals on long jobs.
  
• Use dielectric grease on all electrical connections to prevent corrosion.
  
• Label wires during disassembly to avoid confusion during reinstallation.
  
• If bolts shear off during coil removal, weld nuts onto the remnants and back them out slowly after cooling.
  
• Check for manual override plungers on the solenoid body—these can be used to extend the outrigger in emergencies.
  

Steering System Observations
Some operators report asymmetrical steering performance, such as strong left turns but weak right turns. This may be due to:

• Uneven hydraulic pressure from the steering pump
  
• Internal leakage in the steering cylinder
  
• Contamination in the steering valve spool
  

The rear steering system typically runs on the general hydraulic circuit, not a dedicated pump. Cleaning the valve and checking for pressure balance can resolve directional bias.
Conclusion
Outrigger failure on the Grove RT-60S is often a result of solenoid coil damage or electrical connection issues. With methodical diagnostics and basic tools, the problem can be resolved quickly and affordably. Understanding the crane’s hydraulic and electrical architecture is essential for field repairs, especially when working under time constraints. The RT-60S remains a reliable lifting platform, and with proper maintenance, it continues to perform in demanding environments.