JCB 814 Super slew brake solenoid failure and retrofit options

[MikePhua]

Overview of the JCB 814 Super
The JCB 814 Super is a mid-sized hydraulic excavator introduced in the late 1980s by JCB, a British manufacturer known for its innovation in backhoe loaders and compact construction equipment. Founded in 1945, JCB expanded rapidly through the 1970s and 1980s, with the 814 Super positioned as a versatile machine for general excavation, trenching, and site preparation. It featured a robust undercarriage, a reliable hydraulic system, and a slew brake mechanism designed to hold the upper structure in place during transport or idle operation.
Slew brake solenoid function and failure symptoms
The slew brake on the JCB 814 Super is electrically actuated via a solenoid valve mounted on the hydraulic control block. When energized, the solenoid releases the brake, allowing the upper carriage to rotate freely. If the solenoid fails or loses power, the brake remains engaged by default, locking the swing function.
Common symptoms of solenoid failure include:

• Inability to rotate the upper structure
  
• Blown fuses when energizing the solenoid
  
• No audible click or movement from the valve
  
• Brake remains engaged even when the machine is powered
  

In one case, the operator discovered that the fuse blew immediately upon energizing the solenoid, even with the coil disconnected. This pointed to an internal short or diode failure within the connector or coil windings.
Identifying and sourcing replacement components
The original solenoid was identified as a Rexroth 4WE6 C-top valve, a common directional control valve used in industrial and mobile hydraulics. Rexroth, now part of Bosch, supplies these valves globally, and replacement coils are available in both 12V and 24V configurations.
Key parameters for replacement:

• Voltage: 12V DC (for the JCB 814 Super)
  
• Coil type: C-top mount
  
• Connector: DIN 43650 (standard industrial plug)
  
• Valve body: 4WE6 directional spool
  

Operators should avoid overtightening the four mounting bolts on the valve body, as this can pinch the spool and prevent proper actuation.
Temporary workaround and safety considerations
In situations where the solenoid is unavailable, some operators have considered mechanically jamming the valve in the open position to disable the brake. While this may restore swing function temporarily, it poses safety risks during transport or when parked on uneven terrain. The slew brake is a critical safety feature, and disabling it should only be done with caution and clear signage.
Electrical diagnostics and repair tips

• Disconnect the coil and test continuity across terminals. A short circuit indicates internal coil failure.
  
• Inspect the connector for hidden diodes. Some plugs include flyback diodes to suppress voltage spikes.
  
• Replace only the coil if the valve body is intact. Coils are inexpensive (often under £20) and easy to install.
  
• Verify voltage supply and fuse rating. A mismatch can cause repeated fuse failure.
  

Aftermarket and salvage options
If OEM parts are delayed, operators can explore:

• Rexroth distributors or Bosch hydraulic agents
  
• UK-based dismantlers specializing in JCB parts (e.g., Warburton)
  
• Industrial solenoid suppliers offering compatible coils
  

Ensure that the replacement matches the original voltage and mounting pattern. Some 24V coils may fit physically but will not function correctly on a 12V system.
Conclusion
The JCB 814 Super remains a capable excavator decades after its release, but aging electrical components like the slew brake solenoid can disrupt operations. With accurate identification, careful diagnostics, and access to aftermarket parts, operators can restore functionality without relying solely on factory supply chains. As with all hydraulic safety systems, repairs should prioritize reliability and operator protection.