Three-tube corner joint

In a joint assembly for three tube sections forming the corner of a tube frame, including

• a. a first tube section having a first inner side, a second outer side, and two opposing walls which are perpendicular to the first side;
• b. a second tube section having a first inner side, a second outer side, and opposing walls which are perpendicular to the first side,
• said first and second tube sections being located in a common plane, the first side of said first section and the first side of said second section mutually facing each other;
• c. a third tube section which is arranged perpendicularly to said common plane, and having a plurality of walls including two adjoining lateral faces, with the ends of the first and second tube sections being pressed against said two adjoining lateral faces by a tensioning bolt;
• and
• d. a tensioning piece having ends which are hooked into openings provided in the mutually facing sides of the first and second tube sections, said tensioning bolt extending through a hole in said tensioning piece and engaging in a diagonally disposed threaded hold of the third tube section;
• the improvement wherein:
• the mutually facing sides of the first and second tube sections are exclusively restrained at locations which are immediately adjacent to the two opposing walls of the first and second tube sections;
• the tensioning piece has a U-shaped cross section in a plane which is perpendicular to the common plane in which the first and second tube sections are located, said tensioning piece includes a transverse web extending transversely to the first and second sections and two spaced-apart legs which are parallel to said common plane in which the first and second tube sections are located, said U-shape being defined by said transverse web and said two spaced-apart legs;
• the mutually facing sides of the first and second tube sections have slots immediately adjacent to the opposing walls, the legs of the tensioning piece have boundary portions which engage in these slots;
• the bolt bears against the tranverse web of the tensioning piece;
• and
• the transverse web of the tensioning piece has lobes at its ends, and the lobes bear against the external surfaces of the mutually facing sides of the first and second tube sections.

In a joint assembly for three tube sections forming the corner of a tube frame, including

• a. a first tube section having a first inner side, a second outer side, and two opposing walls which are perpendicular to the first side;
• b. a second tube section having a first inner side, a second outer side, and opposing walls which are perpendicular to the first side,
• said first and second tube sections being located in a common plane, the first side of said first section and the first side of said second section mutually facing each other;
• c. a third tube section which is arranged perpendicularly to said common plane, and having a plurality of walls including two adjoining lateral faces, with the ends of the first and second tube sections being pressed against said two adjoining lateral faces by a tensioning bolt;
• and
• d. a tensioning piece having ends which are hooked into openings provided in the mutually facing sides of the first and second tube sections, said tensioning bolt extending through a hole in said tensioning piece and engaging in a diagonally disposed threaded hole of the third tube section;
• the improvement wherein:
• the mutually facing sides of the first and second tube sections are exclusively restrained at locations which are immediately adjacent to the two opposing walls of the first and second tube sections;
• the tensioning piece has a U-shaped cross section in a plane which is perpendicular to the common plane in which the first and second tube sections are located, said tensioning piece includes a transverse web extending transversely to the first and second tube sections and two spaced-apart legs which are parallel to said common plane in which the first and second tube sections are located, said U-shaped being defined by said transverse web and said two spaced-apart legs;
• the mutually facing sides of the first and second tube sections have slots immediately adjacent to the opposing walls, the legs of the tensioning piece have boundary portions which engage in these slots;
• the bolt bears against the transverse web of the tensioning piece;
• and
• the third tube section has a pair of opposing corners with each corner being formed by one of said two adjoining lateral faces, the outer sides of the first and second tube sections abut against the two adjoining lateral faces at these corners, a clamping piece with a threaded hole is arranged inside of the third tube section, said clamping piece bracing itself essentially in said opposing corners of said third tube section.