In the crash tests performed in 1960-61 by Automotive Safety Research Project in the Mechanical Engineering Department of the University of Minnesota, the test data for the forces on a human being held by a seat belt was based upon the effectiveness of the hydraulic shock-absorbing bumper, a 50-cycle per second natural frequency seat belt and a seat belt tightener without release. The present paper presents an analytical study of the same system with the seat belt tightener connected directly to the hydraulic bumper; the tightener cylinder being thus loaded and unloaded with the bumper. Under this system, a seat-belt force is held to ¼ the force otherwise produced on a seat belt without a bumper and retraction. This condition was suggested on page 82 in the original paper, "Reduction in Crash Forces," James J. Ryan, Chapter 5, Proceedings of the fifth Stapp Automotive Crash and field Demonstration Conference, University of Minnesota, September 14-16, 1961, pp. 48-89, but the means was not determined. Work on an analog computer, as described here, has shown the direct connection of the seat-belt tightener and the hydraulic bumper will perform this function effectively.