ISO 7181:1991
Hydraulic fluid power -- Cylinders -- Bore and rod area ratiosstandard by International Organization for Standardization, 10/01/1991
Specifies for each pair of diameters (AL = cylinder bore; MM = piston rod diameter) of cylinders a corresponding standard ratio between the useful areas A1 and A2. This second edition cancels and replaces the first edition (1982).