This International Standard specifies procedures for the determination of steel-on-steel anti-wear properties of hydraulic fluids by means of performance in a vane-type hydraulic pump. It covers a range of hydraulic fluids, both anhydrous and aqueous, intended for applications where high-speed sliding contacts, such as those found in a vane pump, are encountered. For mineral oils of categories HM and HV, and fire-resistant fluids of category HFD, the method is applicable to viscosity classes ISO VG 32, ISO VG 46 and ISO VG 68, as specified in ISO 3448[1]. Under different specified conditions, the method is applicable to aqueous fire-resistant hydraulic fluids in categories HFA, HFB and HFC, as specified in ISO 12922[3], within the same viscosity classes. NOTE Viscosity classes below ISO VG 32 and above ISO VG 68 can be tested by this technique, but require different conditions of pump inlet viscosity, and have not been widely assessed. This International Standard is confined to the specified limiting values defined.