Seat suspension

Claim 1

In a seat suspension comprising an upper frame, a lower frame, a pair of X-shaped links disposed between said upper frame and said lower frame such that one of the links is disposed at the left side of said upper and lower frame while the other of the links is disposed at the right side of said upper and lower frames, each of said pair of X-shaped links being made up of (a) a first link component having a forward upper end portion at the upward positioned end thereof and a rearward lower end portion at the downward positioned end thereof and (b) a second link component having a forward lower end portion at the downward positioned end thereof and a rearward upper end portion at the upward position thereof, the arrangement of said first and second link components being such that the first link component is rotatably, pivotally fixed to the second link component at the center portion of each thereby allowing the first and second link components to be freely rotated independently of each other, each of said pair of X-shaped links being connected to said upper frame such that one of said forward upper end portion of said first link component and said rearward upper end portion of said second link component is rotatably fixed to said upper frame while the other of said forward upper end portion of said first link component and said rearward upper end portion of said second link component is slidably supported by said upper frame; and each of said pair of X-shaped links being connected to said lower frame such that one of said forward lower end portions of said second link component and said rearward lower end portions of said first link component is rotatably fixed to said lower frame while the other of said forward lower end portions of said second link component and said rearward lower end portions of said first link component is slidably supported by said lower frame, and a pair of tension springs disposed above, and adjacent to, said pair of X-shaped links, the improvement comprising: (a) a pair of bell cranks rotatably, pivotally supported at substantially the center portion thereof; (b) rotatable means for operating said pair of bell cranks; (c) a pair of shock absorbers, the arrangement of said pair of shock absorbers being such that one of the shock absorbers is disposed at one lateral side of said pair of X-shaped links while the other of the shock absorbers is disposed at the other lateral side of said pair of X-shaped links, and further, that one end of each shock absorber is rotatably connected to said pair of X-shaped links, respectively; and wherein said pair of tension springs are each connected at one end thereof to one of said forward upper end portions of said first link component and said rearward upper end portion of said second link component and connected at the other end thereof to one end portion of each of said pair of bell cranks.