Apparatus clutch controlled closure means for a molding

A molding machine which is arranged to perform molding by means of at least one mold constituted by a pair of mold parts, comprising:

• a stationary frame;
• a fixed platen holding one of said pair of mold parts;
• a movable platen holding the other of said pair of mold parts, said movable platen being attached to said stationary frame for reciprocal movement with respect to said fixed platen in a direction toward and away from said one of said pair of mold parts;
• a shaft having an axis extending toward said movable platen, said shaft being supported for rotation with respect to said stationary frame and for reciprocal movement along said axis of said shaft, said shaft having first and second threaded portions formed thereon along said axis of said shaft;
• an electrical motor mounted on said stationary frame for causing rotation of said shaft;
• first and second nut members screwed onto said respective first and second threaded portions of said shaft, said first nut member being secured to one of said stationary frame and said movable platen, said first nut member and said shaft being movable with respect to each other when said shaft is rotated, said second nut member capable of being rigidly coupled with the other of said stationary frame and said movable platen;
• and
• clutch means disposed between said other of said stationary frame and said movable platen and said second nut member for free movement between an engagement position which allows for relative movement between said shaft and said second nut member while said shaft is being rotated with said second nut member rigidly coupled with said other of said stationary frame and said movable platen and a disengagement position which allows said shaft to be rotated together with said second nut member while said shaft is being rotated with said second nut member released from rigid coupling with respect to said other of said stationary frame and said movable platen.