Abstract: An essentially C-shaped tool holder (10), preferably having a long inner edge, which holder at its free shank ends can carry a tool such as a riveting, glueing or welding unit. The holder (10) comprises a truss or frame work which includes an outer and an inner C-shaped frame (11, 23) and a plurality of slewing brackets (27-32) connected to the C-shaped frames. The frames (11, 23) and the slewing brackets (27-32) are arranged to form a number of connected triangular sections, defined by connection points 18-22, 37) which are designed as intersections or joints. The outer C-shaped frame (11) is arranged to support only thrust forces; the inner frame (23) is arranged to support thrust and tensile forces, and the slewing brackets (27-32) are arranged substantially to support tensile forces.