Self centering quick-change cutting tool assembly

A tool mounting assembly for a gear hobbing machine having a drive spindle and an outboard bearing support in axial alignment with said drive spindle, said tool mounting assembly comprising a first coupling unit for detachably connecting one end of a hob in driving engagement with said drive spindle, and a second coupling unit for detachably connecting the other end of said hob to said outboard bearing support, said first coupling unit including a first coupling member secured to the outer distal end of said drive spindle and a second coupling member secured to the outer end face of one end of said hob, said first and second coupling members having a plurality of radially extending teeth which cooperatively intermesh in a disengageable driving relationship to self-center said one end of said hob, and an outboard support unit including a plunger rotatably mounted in said bearing support and axially displaceable between a hob coupling position and unload position said outboard support unit having and a drive means for selectively moving said plunger parallel to the axis of said drive spindle between said hob coupling and said unload positions, said second coupling unit including a first portion secured to the other end of said hob and a second portion secured to said plunger, said first and second portion of said second coupling unit including axial nesting means for self centering said other end of said hob, said plunger drive means providing sufficient end thrust force on said plunger when in said hob coupling position to maintain said hob concentric with the axis of said drive spindle and to hold said first and second members of said first coupling unit in a rigid driving intermeshing relationship.