Two single row annular ball bearings selected dimensionally to be a matched pair or set. The ring faces have been specially ground to specified offsets that will produce predetermined preload when mounted. May include a single row angular contact bearing with faces specially ground for duplex mounting.
mil-g-18709 mil spec single material response lubrication material document and classification, 1.3778 inches minimum and 1.3780 inches maximum bore diameter, light bearing preload designation, angular load direction, tight internal fit-up designation