Abstract: Methods and apparatus for testing automotive and truck wheels and hubs include placing a wheel connected to a hub and an arm or axle like member into a frame which maintains the wheel relatively fixed. Actuators are provided to apply forces to the wheel through the axle and hub. The forces are applied in different directions with the actuators being programmed to simulate actual road conditions over a long period of time in a relatively short test time without requiring substantial rotation of the wheel.

Abstract: An environmental testing system for a product such as a railway car or a trailer includes a seismic mass having a "T" shaped cross-section, supported by a plurality of air mounts or cushioning means. The seismic mass is subjected to compression due to post tensioned reinforcement in three directions. A plurality of actuators are connected between the seismic mass and the product being tested to vibrate the product in accordance with a desired program. The reaction forces from the product under test are absorbed by the seismic mass and the air mounts. The air mounts are connected in series with a large air reservoir to permit the system to be tested under very low resonant frequency conditions.