Semi-active damping of heavy vehicles

A seat construction comprising a frame including a base and a back. Each of the base and back have a frame with spaced side rails and a spring assembly mounted on the frame. Each spring assembly comprises a plurality of longitudinally extending wires, a plurality of transversely spaced wires having intermediate portions extending between the spaced wires and free ends extending beyond the longitudinally extending wires at an acute angle to the intermediate portion. Each spring assembly further comprises a longitudinal wire along each side edge connecting the free ends of said transversely spaced wires. Each spring assembly is embedded in a body of resilient foam plastic material.