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Peterbilt 567, 579, and 589 with Hendrickson PRIMAAX EX


Just because the work is heavy-duty doesn’t mean the ride needs to be. While air suspensions have high initial costs, they can make for a smoother ride, improve the fuel economy, and create less untimely wear and tear on the truck body and equipment. Peterbilt Motors Company expands its partnership to Hendrickson Truck Commercial Vehicles by adding the PRIMAAX® EX, a severe-duty vocational air suspension system, to its suspension offerings.


The PRIMAAX EX improves durability and performance while delivering a substantial weight-savings alternative to competitive systems. In addition to improved handling and resistance to torque rod bushing walk-out, the suspension is available in the capacities of 46,000 and 52,000 lbs with a 10-inch ride height, which is compatible with drum and air disc brakes. The suspension provides amplified stability and handling for vehicles with heavy loads and high centers of gravity, creating an easy ride that will keep the truck level through bumps, dips, and turns.

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The advanced suspension offers customers the opportunity to expand their options to configure their trucks with specific applications that will meet their needs and fulfill the demands of vocational and severe-service, such as construction, refuse, mixer, and heavy-haul applications. The PRIMAAX EX is available as a part of the chassis enhancements on Peterbilt Models 567, 579, and 589.

The PRIMAAX EX is approved for vocational and heavy-haul vehicle applications including: truck, tractor, dump, front and rear discharge mixer, crane mounted, platform, specialty, and vehicles equipped with outriggers. All applications must comply with applicable Hendrickson specifications and must be approved by the respective vehicle manufacturer with the vehicle in its original, as-built configuration.


Along with a rugged, weight-efficient design, the PRIMAAX EX possesses state-of-the-art cast structural beams made up of premium materials for higher reliability, joint integrity, and increased ground clearance, which is enhanced by frame hangers that meet a variety of grueling vocational and severe-duty applications. The optimized suspension geometry contributes to more than twice the roll of stability of competitive air suspensions, helping improve the handling and roll stiffness for expanded applications while significantly controlling suspension-induced driveline vibration.

Additional features include:

  • Integrated end caps on the cast structural beams form a solid connection with the square cross brace to form a rigid torsion system for improved stability and control without the need for re-torque
  • Off-road mobility with up to 12.5 inches of diagonal wheel travel and 8 inches of vertical axle travel for improved traction with 10.75 inches of ground clearance so trucks can traverse uneven terrain on more demanding jobsites
  • Large-volume air sprints that lift and support the load with less air pressure while maximizing driver comfort and equipment protection
  • Premium, heavy-duty bushings that require no lubrication for reduced maintenance and have been tested for longer service life
  • QUIK-ALIGN® system that helps simplify axle alignment for reduced maintenance time and extended tire life
  • D-pin axle connection and clam group reduces stress input to the axle housing by transferring the torsional loads to the integrated stabilizer system, helping extend axle and joint service life


With rough work and even rougher roads, the PRIMAAX EX could be the answer to increasing driver confidence and control, and to getting the most out of your truck without prematurely maxing out its life cycle. Initial costs can be daunting, but the undeniable versatility, enhanced safety, improved fuel economy, and reduced maintenance costs can more than make up for it in the long run.

For More Information

Peterbilt Motors Company has a complete lineup of diesel, natural gas, and electric vehicles, and has earned a global reputation for superior engineering, quality, and craftsmanship. Hendrickson Truck Commercial Vehicles is a leading global manufacturer and supplier of medium- and heavy-duty mechanical, elastomeric, and air suspensions, and more. Find out more at and 

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