Murray 9-Axle Trailer Functionality and Field Maintenance

[MikePhua]

The Rise of Murray Trailers in Heavy Haulage
Murray Trailers, founded in the mid-20th century in California, carved its niche in the specialized transport industry by producing durable, high-capacity trailers for agricultural, industrial, and construction applications. Known for their lowboy and multi-axle configurations, Murray trailers became a trusted choice for moving oversized loads such as excavators, cranes, transformers, and wind turbine components.
The 9-axle Murray trailer is a prime example of engineering tailored for extreme weight distribution. Designed to comply with bridge laws and axle load regulations across multiple states, this trailer allows operators to haul loads exceeding 100 tons while maintaining legal road limits. By the early 2000s, Murray had delivered hundreds of these units across North America, especially to energy contractors and infrastructure haulers.
Core Specifications and Load Distribution
Typical configuration of a Murray 9-axle trailer includes:

• Axle count: 9 (often in 3-axle groups with spread spacing)
  
• Gross vehicle weight rating (GVWR): 200,000+ lbs
  
• Deck length: 26 to 30 feet (main deck), with optional booster or jeep
  
• Suspension: Air ride or spring, depending on application
  
• Tire size: 255/70R22.5 or equivalent
  
• Braking system: Air-actuated with ABS integration
  

Terminology notes:

• Booster axle: An additional axle group mounted behind the trailer to distribute rear weight.
  
• Jeep dolly: A front axle group placed between the tractor and trailer to handle tongue weight.
  
• Spread axle: Axles spaced apart to reduce per-axle load and comply with bridge formulas.
  

In one case from Alberta, a contractor used a Murray 9-axle to haul a 110-ton generator across provincial borders. The configuration included a 3-axle jeep, 5-axle trailer, and 1-axle booster, allowing legal travel without special escort.
Hydraulic Systems and Steering Integration
Many Murray 9-axle trailers feature hydraulic steering systems on the rear axles to improve maneuverability. These systems are especially critical when navigating tight turns or urban delivery zones.
Key components include:

• Hydraulic steering cylinders
  
• Control valve block
  
• Manual override lever
  
• Pressure accumulator
  
• Steering linkage arms
  

Common issues:

• Cylinder drift due to seal wear
  
• Hose abrasion from road debris
  
• Valve sticking in cold weather
  
• Air intrusion causing erratic movement
  

In Texas, a wind farm crew reported sluggish steering response on their booster axle. After inspection, the hydraulic fluid showed signs of water contamination. Flushing the system and replacing the accumulator restored full control.
Electrical and Lighting Systems
Given the trailer’s length and complexity, electrical integrity is vital for safety and compliance. The lighting system includes:

• LED marker and clearance lights
  
• Brake and turn signals on each axle group
  
• ABS sensors and warning indicators
  
• Extendable harnesses for jeep and booster connections
  

Maintenance tips:

• Use dielectric grease on all connectors
  
• Replace damaged harness sections with shielded cable
  
• Test ABS function monthly using diagnostic plug
  
• Install backup battery for emergency lighting
  

In Florida, a contractor added solar-powered marker lights to the outer edges of his Murray trailer to improve visibility during night hauls. This reduced roadside inspection delays and improved safety on rural highways.
Deck and Structural Integrity
The main deck of a Murray 9-axle is built from high-tensile steel, often reinforced with crossmembers and gussets. Over time, stress from heavy loads can cause fatigue or weld cracking.
Inspection checklist:

• Check welds at crossmember junctions for hairline cracks
  
• Inspect kingpin plate for wear or distortion
  
• Verify deck camber under load (should remain within spec)
  
• Grease all pivot points and ramps
  
• Conduct ultrasonic testing every 5,000 hours
  

Terminology notes:

• Camber: The slight upward curve of the deck when unloaded, designed to flatten under load.
  
• Kingpin plate: The steel plate that interfaces with the tractor’s fifth wheel, critical for load transfer.
  

In Oregon, a logging operator reinforced his trailer’s deck with bolt-on steel plates after noticing flex during crane transport. The modification extended deck life by 30% and improved load stability.
Brake System and Air Management
The braking system on a 9-axle trailer must be meticulously maintained to ensure synchronized stopping power. Components include:

• Air tanks and lines for each axle group
  
• Brake chambers and slack adjusters
  
• ABS modulator valves
  
• Emergency spring brakes
  

Best practices:

• Drain air tanks weekly to remove moisture
  
• Inspect slack adjusters for proper stroke (should be under 2 inches)
  
• Replace brake shoes every 30,000 miles or as needed
  
• Test emergency brake release under load
  

In New Mexico, a contractor experienced brake fade during a mountain descent. The issue was traced to a failed modulator valve on the booster axle. After replacement and system bleed, braking performance returned to normal.
Parts Availability and Sourcing Strategies
While Murray Trailers no longer manufactures new units, parts remain accessible through:

• Specialized trailer parts distributors
  
• Hydraulic shops offering custom hose and cylinder rebuilds
  
• Salvage yards with multi-axle trailer inventory
  
• Fabrication shops for deck and frame components
  

Recommended sourcing tips:

• Use axle serial numbers to match brake and suspension parts
  
• Cross-reference hydraulic seals with Parker or NOK equivalents
  
• Seek remanufactured steering cylinders from crane trailer suppliers
  

In South Dakota, a contractor rebuilt his steering system using parts from a retired Talbert trailer. The retrofit required minor machining but restored full functionality.
Operator Stories and Field Wisdom
In Tennessee, a heavy haul crew used a Murray 9-axle to transport bridge beams across three states. The trailer’s stability and modular axle layout allowed them to meet varying DOT requirements without reconfiguring the load.
In Chile, a mining firm deployed a refurbished Murray trailer to move a 95-ton crusher. After upgrading the lighting and brake system, the trailer operated safely for 1,200 hours without incident.
Conclusion
The Murray 9-axle trailer remains a symbol of specialized transport engineering. Though no longer in production, its legacy endures through thousands of successful hauls and field adaptations. With disciplined maintenance, creative sourcing, and a deep understanding of its systems, operators can continue to rely on this trailer for the heaviest and most complex loads on the road.