Dismantling the Front Hub of a MF50HX with Carraro 710LP Axle

[MikePhua]

The MF50HX and Its Mechanical Heritage
The Massey Ferguson MF50HX was part of a lineage of backhoe loaders designed for rugged utility in construction and agricultural sectors. Released during the 1980s, the MF50HX combined Massey Ferguson’s agricultural engineering roots with Carraro’s drivetrain expertise. Carraro, an Italian manufacturer renowned for its axles and transmissions, supplied the 710LP front axle—a planetary hub design built for durability and torque distribution.
Massey Ferguson, founded in 1847 and later merged into AGCO Corporation, was a global leader in agricultural machinery. The MF50HX was widely sold across Europe and Commonwealth countries, with thousands of units deployed in municipal works, rural infrastructure, and farm maintenance. Its popularity stemmed from its mechanical simplicity, parts availability, and robust performance in off-road conditions.
Understanding the Carraro 710LP Axle
The Carraro 710LP is a planetary reduction axle, meaning it uses a set of planetary gears within the hub to multiply torque while reducing speed. This design is ideal for loaders operating in soft terrain or under heavy loads. The axle features:

• A crown gear (ring gear) mounted inside the hub
  
• Planetary gears rotating around pinion shafts
  
• A wheel carrier that houses the entire assembly
  
• Roll pins securing the pinion shafts
  
• A lock ring retaining the crown gear
  

These components are tightly fitted and often require mechanical force to disassemble, especially if the hub has seized due to bearing failure or lack of lubrication.
Common Failure Points and Symptoms
In the case of the MF50HX, the front hub had seized due to a failed bearing—likely exacerbated by prolonged operation without oil. Planetary hubs are designed to run in an oil bath, and dry operation leads to rapid wear, overheating, and gear seizure. Symptoms include:

• Locked planetary gears
  
• Excessive resistance during steering
  
• Grinding or metallic noise from the hub
  
• Visible dryness or corrosion inside the hub cavity
  

Operators should routinely check final drive oil levels, especially after purchasing used equipment. A common oversight is assuming all fluids were topped off during a “full service,” when in reality, final drives are often neglected.
Disassembly Procedure and Techniques
Removing the wheel carrier and crown gear from a seized Carraro 710LP hub requires a methodical approach. Key steps include:

• Use the four threaded holes in the carrier to insert bolts and jack the carrier off the axle stub. This technique applies even pressure and avoids damage to the housing.
  
• Expect resistance if the planetary gears are locked. The ring gear is retained by a lock ring on the backside, so the entire assembly must be pulled out before separating components.
  
• Drive out the roll pins securing the pinion shafts. These pins are press-fit and may require heat or penetrating oil if corroded.
  
• If the gears are seized in the bearings, consider using a hydraulic press or custom puller. Avoid hammering directly on gear teeth to prevent chipping.
  

Terminology Clarification

• Planetary Gear Set: A gear system consisting of a central sun gear, surrounding planet gears, and a ring gear. Used for torque multiplication.
  
• Wheel Carrier: The outer hub structure that supports the wheel and houses the planetary gear set.
  
• Crown Gear: Also called the ring gear, it meshes with the planet gears and transmits torque.
  
• Roll Pin: A spring-loaded pin used to secure shafts in place. Often used in gear assemblies.
  
• Lock Ring: A retaining ring that holds components in axial position, typically requiring snap ring pliers for removal.
  

Field Anecdote and Practical Insight
One technician in Lancashire, UK, shared his experience dismantling a seized MF50HX hub. After struggling with a standard hub puller, he discovered the threaded holes in the carrier were designed for bolt jacking. Once the carrier was removed, he found the planetary gears locked solid, likely due to years of dry operation. The machine had been sold with claims of a full service, but final drives were bone dry—a costly oversight.
This story echoes a broader lesson in used equipment acquisition: always verify fluid levels personally. Even seasoned operators have been misled by well-meaning sellers or incomplete service records.
Preventive Maintenance Recommendations
To avoid similar failures in planetary hubs:

• Check final drive oil every 100 hours or monthly, whichever comes first.
  
• Use high-quality gear oil rated for extreme pressure (EP), such as SAE 85W-140.
  
• Replace hub seals during bearing replacement to prevent future leaks.
  
• Inspect roll pins and shafts for wear or deformation during reassembly.
  
• Torque carrier bolts to manufacturer specifications to avoid warping the housing.
  

Restoration and Long-Term Reliability
Once dismantled and cleaned, the Carraro 710LP hub can be restored to full functionality with new bearings, seals, and gear oil. Reassembly should be done with care, ensuring proper alignment of planetary gears and secure seating of the crown gear. With proper lubrication and periodic inspection, the MF50HX can continue serving reliably for years.
In fact, many municipalities still operate MF50HX units for snow removal and trenching, a testament to the machine’s enduring design. Carraro axles remain a preferred choice in modern equipment, now found in brands like JCB, Manitou, and Merlo.
Conclusion
Dismantling the front hub of a MF50HX equipped with a Carraro 710LP axle is a challenging but rewarding task. It requires mechanical intuition, proper tools, and a clear understanding of planetary gear systems. With patience and attention to detail, operators can restore seized hubs and extend the life of these classic machines. The MF50HX, like many legacy loaders, proves that with care and knowledge, even decades-old iron can be brought back to life.