Abstract: The apparatus is one by which blanks are changed automatically in a hobbing machine of the general type comprising at least one tool head capable of movement along horizontal and vertical axes and consisting essentially in a horizontal spindle and a coaxial outer bearing that can be moved toward and away from one another, between which a tool is supported and set in rotation; in the apparatus disclosed, a vertical post rotatable about its own axis carries a number of peripheral supports that feature two dissimilar structures, the one designed to restrain and/or support a tool and the other a blank, in such a way that the tool currently fitted to the head can be discarded and a replacement tool supplied automatically, utilizing the one type of support, whilst the blanks are changed by the other type.

Abstract: In a hobbing machine of the type with a pair of coaxial heads driving a hob supported between them, one of which capable of movement toward and away from the other and one affording a key positioned to engage a slot associated with the hob, the slot is incorporated directly into the hob, and each head carries an axially hollow alignment spigot with a stop collar, matched to and insertable in the axial bore of the hob to a depth determined by interaction of the relative collar with the end of the hob; equipping one of the heads with a coaxial tension rod insertable through the bore of the hob, and the other head with a clamping mechanism capable of gripping and tensioning the rod, the necessary rigidity is obtained without the use of an arbor.