Knob-type closure device

A knob closure device for operating and locking two surfaces which are axially movable with respect to each other, comprising:

• a pin provided with means for fixing in a hole of the first surface and with two annular end grooves;
• a hollow body provided with means for fixing in a hole defined in said second surface, said hollow body supporting, on one side thereof, an actuation knob, and on the other side thereof, a disengagement cyilinder so that said knob and said cylinder can move axially and rotate, said knob and said cylinder being coupled;
• a central bushing, which is rigidly coupled to said hollow body and in which two oppositely arranged inclined slots are formed;
• said slots converging towards each other and towards the free end of the bushing;
• two transverse shafts that are slidingly mounted in said slots and are pushed by a compression spring arranged between the bottom of the bushing and a washer which rests on the shafts, in a configuration for tangential engagement in said annular grooves to couple the pin to the bushing;
• a cam profile rigidly coupled to the inlet of the hollow body, against which a diametrical stem of the knob engages, said stem being adapted to cause, by virtue of the rotation of the knob and the sliding against the cam profile, the axial sliding of the end of the cylinder move said shafts into positions spaced from said stem and cause the disengagements of said shafts;
• a cap mounted, in contrast with elastic means, on the bottom of said hollow body and adapted to push, in the direction for expulsion, the end of said pin that is inserted in said body.