Abstract: The invention relates to a spring pre-assembly for a mattress foundation unit having a wooden base, a plurality of spring units and a mattress supporting wire grid that is supported above the wooden base by the spring units. The spring pre-assembly comprises a plurality of spring units connected to a wire grid consisting of a plurality of grid wire pairs arranged orthogonally to one another. The spring units include a base portion, a pair of divergently extending leg portions and a pair of engagement portions extending in opposite directions from the distal ends of the leg portions. The engagement portions can be engaged with adjacent grid wire pairs, the resulting arrangement being such that the spring units are pre-stressed.

Abstract: The invention relates to a modular spring for a mattress foundation unit having a wooden base a plurality of modular springs and a mattress supporting wire grid that is supported above the wooden base by the modular springs. The modular spring comprises a planar top portion which can be attached to the wire grid, four straight legs and each leg terminating in a transverse foot portion. The top portion includes four partially curved spaced apart members. The legs extend downwardly from the top portion in an obtuse angular relation to the top portion and each leg interlinks two adjacent partially curved members.