Spring group

Claim 1

In an energy dissipating cushioning mechanism that includes a tandem arrangement having first and second deflectable load bearing structures interacting in series for transmitting load forces therethrough, the improvement wherein one of said structures includes concentric inner and outer bodies each being of compressible urethane material having a hardness in the range from about 60 to about 90 Shore A, means mounting said inner and outer bodies in radially spaced relation to undergo deflection along a common axis, with said bodies, when free of load, presenting load receiving surfaces in an axially offset relation and said bodies having load bearing determining shapes wherein one of said bodies undergoes individual initial axial compression for substantially carrying the static load forces and wherein said bodies undergo joint axial compression in radially contacting relation to dissipate energy in reacting to additional travel due to load oscillation, the other of said structures comprises a coil spring having a spring rate that is a small fraction of the spring rates of either of said bodies whereby said coil spring is deflectable through substantially fulL stroke prior to substantial deflection of either of said bodies and said arrangement includes means to restrict deflection of said coil spring prior to full stroke deflection thereof thereby preventing damage to said coil spring when said load forces exceed the load capacity of said coil spring.