VIPER's custom-designed 8-post test rig represents the next generation of suspension testing equipment. It has several advantages over today's 7-post rigs.
Body actuators are pneumatic instead of hydraulic. This reduces the force feedback (in the actuators) caused by body motions, so inertial and aerodynamic forces are applied to the vehicle body more accurately.
The addition of an eighth actuator to the traditional seven that are typically employed allows moments to be applied at both ends of the vehicle simultaneously. Applying moments at just one end (as performed by a 7-post) introduces artificial frame twist into the chassis, which in turn affects the accuracy of the loads at the tire.
8-post setup also allows kinematic and compliance measurements such as axle roll stiffness, chassis torsional rigidity, and vertical spring rate.
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