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LORD MR Shock Durability Exceeds HMMWV Passive Damper Spec by Factor of Four


LORD Corporation has announced the performance level of their Magneto-Rheological (MR) active shock absorbers for military vehicle primary suspensions.

In recent lab testing conducted by LORD, MR active shock absorbers for HMMWV and other military vehicle primary suspensions surpassed 4-million cycles of durability testing. In some cases, the LORD MR shocks exceeded 5-million cycles.

"This is a significant milestone," said Steve Hildebrand, MR suspensions engineering manager. "The MR shocks exceed the HMMWV passive damper specification, which requires a sinusoidal test of 1-million cycles up to 120C. In addition, our tests are run with sine-on-sine with a side-load at higher temperatures, which is more severe, yet we exceed the HMMWV passive damper test specification by a factor of four or more. And, post-test analyses reveal no degradation of MR fluid."

Testing also included severe off-road HMMWV mission profiles with a side load. The vehicle-based durability testing exceeded 15,000 miles of accelerated, off-road operations with no degradation of MR fluid.
LORD has been designing and testing production-intent hardware for more than a year.

"Building on the success of our partners and early engineering prototype demonstrations that showed the performance benefits of MR damping, we now have a viable production solution," said Jesse DePriest, MR suspensions business development manager.

LORD Corporation's MR technology has been proven through the licensing and broad intellectual property portfolio used in developing BWI Group's MagneRideTM suspension system. First introduced on the 2002 Cadillac Seville, the system now appears on more than 500,000 devices in more than a dozen models from multiple automotive OEMs including Audi, Ferrari, GM, and Holden Special Vehicles. The rapid acceptance of the technology by a wide range of manufacturers, from high-performance sports cars to SUVs, demonstrates the confidence the automotive industry has in the performance, reliability and durability of LORD MR technology.

In a related effort, LORD has completed initial qualification testing of the mil-specification compliant MR shock system controller. The controller hardware is designed to accommodate any military vehicle, wheeled or tracked, 4x4 up to 8x8 wheel-ends. Realizing that some vehicles will require full military specification compliance and that the customer will realize the benefits of commonality in hardware among platforms, a single box was designed for all applications. The controller is compliant to mil-specifications MIL-STD-1275 for power quality, MIL-STD-461 for EMC/EMI, and MIL-STD-810 for environmental factors. Further, it is capable of a 40-inch fording submersion (box depth), the connectors are MIL-DTL-38999 compatible, and the system is J1939 data bus compliant.

"The LORD MR shock system is very effective, providing a significant performance benefit with very little electrical power and simple retrofit," said Hildebrand. "For example, on a Belgian-Block course, electrical power draw was only ¼ W mean per wheel station. Since the MR dampers run cooler than passive, they provide a measurable improvement to fuel efficiency."

Unlike traditional passive suspensions with fixed characteristics, LORD Corporation's controllable MR suspensions react to vehicle and terrain conditions thousands of times per second, allowing the suspension to adapt its characteristics to the situation. This provides improved dynamic stability over passively damped systems, which can provide significant benefits.

The use of the MR shocks results in approximately 30 percent less pitch and roll, greatly improving the stability and handling. Further, the system reduces absorbed energy by 50 percent or more and peak loads by about 60 percent. This means the vehicle will experience less wear and tear, resulting in longer vehicle life, greater fuel efficiency, and ensures a much smoother ride and fewer injuries. For the warfighter, the MR shocks offer increased payload, better vehicle performance across a broad range of gross weights and loading conditions, less occupant fatigue, higher speed over terrain, greater maneuverability as well as more accurate weapons firing platform.

"In addition to customer funded development projects, we also have two vehicles that will undergo full-scale performance and durability testing this year, "said DePriest. "The damper durability and controller qualification gives us great confidence that we will easily pass 20,000 miles of durability testing to the vehicle mission profiles. We are very pleased to inform our customers that we have a viable product ready for production applications."