Pivot hinge with removable door closing device

In a pivot hinge for supporting a door at its top end and having a door closing device easily and removably assembled thereto, wherein said pivot hinge has a first plate member including a first leaf portion to be secured to the upper portion of a door frame and a first disk portion projecting horizontally from, and integral with, said first leaf portion, and a second plate member including a second leaf portion to be secured to the top end of the door and a second disk portion projecting horizontally from, and integral with, said second leaf portion, said first and second plate members being connected to one another by a pivot pin at said first and second disk portions, and said door closing device having an outer sleeve in which a door closing mechanism is contained, said door closing device comprises said outer sleeve, an inner member being mounted in said outer sleeve to be rotatable in relation to said outer sleeve and being removably connected to said pivot pin, and a coil spring member disposed within said outer sleeve with the lower end of said spring being connected to said outer sleeve and with the upper end being connected to said inner member so that said coil spring member may be twisted by rotation of said outer sleeve together with said second plate member in relation to said inner member to provide the door closing torque, the improvement comprising said second disk portion being formed with a plurality of first axial grooves in the outer surface thereof, said outer sleeve formed with a plurality of second axial grooves on the inner surface of its top end portion to provide axial ridges between adjacent said second axial grooves, said outer sleeve non-rotatably connected to said second disk portion by mating said first axial grooves with said axial ridges, a supporting disk member superposed onto the upper surface of said second disk portion and being rotatable about said pivot pin, said supporting disk member formed with a plurality of first cut-away portions at its peripheral edge portion for mating with said axial ridges and thereby providing radial projections, said outer sleeve formed with an annular groove intersecting each axial ridge in the inner surface of the top end portion thereof so that each said axial ridge has a radial recess to permit said supporting disk member to rotate in said outer sleeve, said outer sleeve retained to said second disk portion by engagement of said radial projections with said radial recesses.