Patent ID: 6761501
Filing Date: 2004-07-13
Classification: F16B,F16M,Y10T

Abstract:
A telescopic unit including:a first tubular member whose cross section is in the shape of an involute curve; a second tubular member whose cross section is in the shape of an involute curve, which is inserted in said first tubular member so as to be capable of rotating in the circumferential directions and enabling the adjustment of the distance by which the second tubular member projects from the first tubular member; a receiving member in the bottom of said first tubular member; and a catching member on the outer surface of the upper end of said second tubular member, said catching member being adapted to catch said receiving member when said second tubular member projects to its fullest extent; wherein: one or more press receiving surface portions are formed on the inner cylindrical surface of the first tubular member, said press receiving surface portions having a cross section which has an arc-shaped surface such that the center axis of the arc extends in parallel with the center axis of said first tubular member; one or more press applying surface portions are formed on the outer cylindrical surface of the second tubular member, said press applying surface portions having a cross section which has an arc-shaped surface such that the center axis of the arc extends in parallel with the center axis of said second tubular member; rotation of the second tubular member in one direction circumferentially relative to the first tubular member causes given locations of the press applying surface portions to be pressed against the press receiving surface portions, thereby securing the second tubular member to the first tubular member; rotation of the second tubular member in the other direction circumferentially relative to the first tubular member releases the press applying surface portions and the press receiving surface portions from the press-contact with each other so that the distance by which the second tubular member projects from the first tubular member can be adjusted; rotation of the second tubular member in the other direction is limited so as to prevent the given locations of the press applying surface portions to be pressed against the press receiving surface portions; said receiving member is snugly fitted in the bottom of the first tubular member and has a cross section having a shape similar to that of the first tubular base member; and said catching member is snugly fitted around the outer surface of the upper end of the second tubular member and has a cross section having a shape similar to that of the second tubular member.