Oscillation Hitch Design in Volvo A35E and A40E Articulated Haulers

[MikePhua]

The A35E and A40E in Volvo’s Hauler Lineage
Volvo Construction Equipment introduced the A35E and A40E articulated haulers in the mid-2000s as part of its fifth-generation lineup, building on decades of innovation in off-road hauling. These models were designed for high-capacity earthmoving in rugged terrain, with the A35E offering a payload of 35 metric tons and the A40E rated at 39 metric tons. Both machines featured Volvo’s hallmark articulated steering, advanced suspension systems, and Tier 3-compliant diesel engines delivering over 400 horsepower.
Volvo pioneered the articulated hauler concept in the 1960s and has remained a global leader in the segment. By the time the E-series was launched, Volvo had already sold tens of thousands of haulers worldwide, with the A35 and A40 platforms becoming staples in mining, quarrying, and infrastructure development.
Oscillation Hitch Function and Evolution
One of the defining features of Volvo’s articulated haulers is the oscillation hitch—a central pivot point between the tractor and trailer sections that allows the rear frame to move independently over uneven terrain. This design improves traction, reduces stress on the frame, and enhances operator comfort by absorbing shocks and maintaining ground contact.
In earlier D-series models, the oscillation hitch was oil-filled, using hydraulic damping to control movement and reduce wear. This design offered smoother articulation and better longevity under heavy loads. The question arises whether the E-series retained this oil-filled configuration or transitioned to a different system.
While official documentation is limited, field reports and component diagrams suggest that the E-series continued using an oil-filled oscillation hitch, albeit with refinements in seal design and service access. The hitch assembly includes:

• Central pivot pin with spherical bearings
  
• Hydraulic damping chambers filled with oil
  
• Sealed bushings to prevent contamination
  
• Grease fittings for supplemental lubrication
  

This hybrid approach balances the benefits of hydraulic damping with the simplicity of mechanical articulation.
Benefits of Oil-Filled Oscillation Systems
Compared to dry pivot systems, oil-filled hitches offer several advantages:

• Reduced metal-on-metal contact, minimizing wear
  
• Improved shock absorption during high-speed hauling
  
• Lower maintenance intervals due to sealed lubrication
  
• Enhanced stability on uneven ground
  

In high-production environments, these benefits translate to longer component life and fewer unscheduled repairs. Operators report smoother ride quality and better control when traversing rutted haul roads or steep inclines.
Maintenance Considerations and Inspection Tips
Despite their durability, oscillation hitches require regular inspection to ensure continued performance. Recommended practices include:

• Checking oil level and condition every 500 hours
  
• Inspecting seals for leakage or cracking
  
• Verifying pivot pin torque and bushing wear
  
• Monitoring articulation angle sensors if equipped
  

Some E-series haulers include electronic monitoring of hitch movement, alerting operators to excessive oscillation or binding. This feature helps prevent frame damage and improves safety during high-speed travel.
A Story from the Field
In British Columbia, a fleet manager overseeing a dozen A35E and A40E units noticed premature wear in one hauler’s oscillation hitch. After teardown, the team discovered that a seal had failed, allowing dirt to contaminate the oil chamber. The hitch was rebuilt with upgraded seals and a modified breather system. Since then, the fleet adopted a quarterly inspection protocol, reducing hitch failures by 80% over two years.
Recommendations for Long-Term Reliability
To maximize hitch performance:

• Use OEM-approved hydraulic oil with correct viscosity
  
• Replace seals proactively during major service intervals
  
• Avoid overloading beyond rated payload, which stresses the hitch
  
• Train operators to recognize early signs of articulation resistance
  

For fleets operating in extreme cold or abrasive environments, consider installing hitch guards or thermal blankets to protect seals and maintain oil viscosity.
Conclusion
The Volvo A35E and A40E articulated haulers continue the legacy of robust oscillation hitch design, likely retaining the oil-filled configuration that defined earlier models. This system plays a critical role in maintaining stability, reducing wear, and enhancing operator comfort across challenging terrain. With proper maintenance and awareness, the oscillation hitch remains a silent partner in the relentless rhythm of off-road hauling—absorbing the terrain so the machine can keep moving forward.