Clamping device

The device (2) has clamping jaws (3, 4) braced one another via a screw (7) on a pillar (1) of a vehicle i.e. fork-lift truck. A through-hole (6) passes through one of the jaws and sets in another jaw. The former jaw comprises a contact surface (11) for a head (12) of the screw such that the former jaw pivots about a pivot axis (10) when the former jaw is tightened relative to the latter jaw. The surface is made in an acute angle with respect to a screw axis (13) in all positions of tensioning operation such that the head contacts at a point (15) on the pivot axis far away from the screw axis.