Patent ID: 7588042

Claim:
A folding shaft for umbrellas, comprising: a first section having a circular cross section; a second section movably mounted to the first section and including an enclosed cross section which includes a plurality of straight sides and a plurality of first curved portions connected between the straight sides, said first section being telescopingly received within said second section, and a third section movably mounted to the second section and including an enclosed cross section which includes a plurality of inward curved sides each having an arcuate length and a plurality of second curved portions connected between the inward curved sides, the inward curved sides of the third section being located corresponding to the straight sides of the second section and said inward curved sides having a depth in a range between 0.1 and 0.2 of said length of each said inward caved sides, the second curved portions of the third section being located corresponding to the first curved portions, said second section being telescopingly received within said third section.