The removable device for attaching two mechanical parts comprises a pin removably locking a first part with respect to a second part, a retainer member associated to the pin and a resiliently loaded tension member which collaborate to prevent the pin from coming out of its lock position; it is characterized in that it further comprises at least two inclined surfaces, the general shape of which isthat of a projection oriented in the axial direction of the pin, such that when the pin rotates, the retainer member runs along said inclined surfaces and the pin moves between the lock position and unlock position against the force axial to the axis of the pin exerted by said tension member. The assembly and removal of the parts is carried out in a simple manner, but the attachment during operation of the excavator is at the same time secure and reliable.