Patent ID: 7484719

Claim:
A spring comprising: first and second rigid end members moveable relative to each other causing the distance therebetween to vary during operation of said spring; an elastic spring body mounted between said end members; said elastic spring body having a rotationally symmetrical cross section and a longitudinal section having biconvex shape; said elastic spring body being a monolithic body of rubber or a rubber-like plastic and having a surface which is pressed with more or less area of said surface against said rigid end members as said distance becomes shorter or longer during said operation; a first plurality of ribs arranged on said surface spaced one from the other at respective first distances; a second plurality of ribs arranged on said surface spaced one from the other at respective second distances; said second plurality of ribs intersecting said first plurality of ribs so as to form a multiplicity of intermediate spaces defining a corresponding plurality of polygonal areas or cavities on said surface wherein air collects to become trapped between said spring body and said rigid end members to form a plurality of air pillows as said rigid end members move toward each other so as to permit said elastic spring body to slide on said air pillows; said elastic spring body having a substantially U-shaped cavity formed therein so as to impart said biconvex shape to said elastic spring body when viewed in longitudinal section; and, one of said rigid end members having an opening formed therein lying opposite said U-shaped cavity to permit said U-shaped cavity to communicate with the ambient.