The device of the module (3) of the support carries a rotary instruments, intended to equip an automatic device for the disinfection and maintenance of a rotary instruments, comprising a motor (5) adapted to turn the rotary instruments. The motor (5) is housed in a cavity (32) is closed by a cover (6) through which the driving shaft (50) and consisting of the assembly of two concentric parts (7, 8), a tubular, intended to be introduced into the aperture (33), and provided with a system of peripheral joint (j) able to achieve the seal with the module (30), and a system of internal seal (t) adapted to carry out the sealing with the shaft (50), and a second part (8) in the form of a ring, introduced in a rabbet (74) of the first part (7), and comprising a peripheral seal (s) able to achieve the seal with the first part (7), a central bore (75) intended to be traversed closely by the shaft (50), whose dimensions are adjusted in order to produce a seal by sliding clamping.
