Damper disc

Claim 1

A damper disc comprising: a spline hub; a radial flange formed at the hub; a pair of cases rotatably mounted on the spline hub and connected to facings at the radially outer end thereof, each one of said pair of cases being disposed on opposite sides of the flange; circumferentially spaced plural compressible coil spring assemblies operably connecting the cases and the flange together, at least one of said coil spring assemblies including axially aligned and concentric first and second coil springs, said first coil spring disposed within said second coil spring, such that one of said springs begins to compress before the other; a sealed spring chamber formed around each of said spring assemblies by the cases and having only sealed narrow spaces connecting the springs chambers together; and spring seats disposed at both ends of each spring assembly, said chambers being filled with oil, so that the oil provides a resistance force to the moving spring seats and said chambers are only slightly larger in cross-section than said spring seats to enable said spring seats to function as hydraulic pistons, wherein at least one of said spring seats corresponding with said first and second springs has two portions movably independently from each other, a first portion supporting said first spring and a second portion supporting said second spring, said first portion engaging a projection on said flange to cause said first spring to compress before said second spring which is not engaged with said projection.