SCREW AND WRENCH FOR SNUGLY-FITTED TIGHTENINGS

摘要

A screw for snugly-fitted tightening pairs, of the typehaving a lobate head or a lobate-socket head (31), inwhich each lobe (37) is formed of one face (37') directedin a substantially circumferential manner and two othersubstantially parallel faces (35, 36) directed inwardly ofthe screw; said screw is provided with a reaction surface(33) with a tightening wrench (32). The portions of saidreaction surface (33) included between two adjacent lobesare comprised each of a pair of faces (38, 39) inclined toeach other to form an angle concave towards the outside ofthe screw, so as to constitute a reaction surface with awrench of a polygonal profile. Such a screw can beoperated to advantage either with the polygonal wrenchesof the known art, or with an innovatory mating wrench of alobate configuration.