Door closer delayed action speed control system

A door closing device comprising:

• a fluid filled cylinder;
• a piston reciprocally and slidably displaced within said cylinder forming a first, second and third chambers;
• a gear mechanism connected to said piston and adapted to be further connected to a pivotable door in order to transmit opening and closing movements of the door to the piston and vice versa;
• a spring forceably biasing said piston in one of its slidable directions;
• a first valve means, a second valve means, and third valve means which sequentially control the flow of fluid from said first chamber to said second chamber;
• a fourth valve means for automatically controlling said fluid from said third chamber to said second chamber;
• said piston is formed with a piston head and sealing surface at each end jointed together by a reduced center rack gear section;
• said rack section cooperates with a pinion gear to connect said piston to a pivotable door;
• said reduced portion of said piston forms said second chamber;
• a first passage means connects said first chamber with said second chamber sequentially through said first valve means, said second valve means and said third valve means;
• a second passage means communicating between said third chamber and said second chamber through said fourth valve means;
• and
• a third passage means communicating said first fluid passage alternately with said first chamber and said second chamber at a point between said first valve means and said second valve means.