Adjusting device, especiall for a helmet

An adjusting device suitable for adjusting at least one dimension of an object, such as an object intended to be worn by a user, such as a shoe, an item of clothing, a helmet or an accessory, said device comprising a pinion provided with several first teeth of a first height, said pinion being housed free in rotation about an axis in a housing, and at least one first rack provided with at least one row of several second teeth of a second height, said first rack being slid free in translation into said housing, said second teeth cooperating with said first teeth such that rotation of said pinion about the axis causes translation of said first rack,

• wherein
• said first rack is deformable elastically, such that when a force acts on said first rack in the direction opposite the direction of said translation during rotation of the pinion, said first rack undergoes elastic deformation,
• said housing leaves a clearance for the first rack, in the plane of rotation of the pinion and perpendicular to the direction of translation, said clearance being at least equal to the least of said first and second heights respectively of said first and second teeth, such that when the first rack undergoes said elastic deformation, that of the second teeth in cooperation with the first teeth of the pinion disengages from these said first teeth.