Rixson  3/4" appears to be a replacement for Dor-O-Matic and Glynn Johnson 3/4 Pivot hinge

Product Description & Features:
 

Mounting Leg Length: 4-7/8 inch

Mounting Leg Width: 1 inch
 

Used when frame condition does not allow standard top pivot
 

• Lateral load-bearing

• Maintains door alignment

• Aids in installing floor closers and bottom pivots

• Heavy-duty needle bearing

• Non-ferrous base metal

• 3/4" (19mm) offset standard

• Available for 1-1/2" (38mm) offset

• Available for fire door assemblies (ferrous material)

         – specify FM190

• For 20-minute label suffix “–20” to part number

• Doors 60" (1524mm) to 90" (2286mm) in height should use one intermediate pivot. Each additional 30" (762mm) warrants another intermediate pivot.

• Door edges must be beveled in 1/8" in 2"

• Furnished with wood and machine screws