The effect of seat back rotation, head restraint position, and collision speed on crash dummy head acceleration, extension and flexion was determined by tests using an acceleration sled and vehicle collisions. The sled tests were run with a rigid seat and an adjustable back at 10, 20, and 30 mph. Vehicle collisions were conducted with production seats with and without head restraint devices at 10, 15, 20, 25, 30, 40, and 50 mph impact speeds.
Fifty percentile adult male Sierra dummies were used. The head was able to move freely when accelerated backward.
In both sled and vehicle collisions, head restraint devices reduced the measured severity criteria on the crash dummies employed in the tests.