Some Problems of Fluids for Hydraulic Power Transmission

Abstract

The connexion between aircraft, land, and marine hydraulics is emphasized, especially in regard to the working fluid and the sealing problems. The ideal fluid which would suit all cases does not, as yet, exist. The properties, advantages, and disadvantages of a number of well known, and a few lesser known, fluids are discussed. The fluids include those based on petroleum, castor, water-glycol, halogenated, and synthetic compounds. The properties covered include viscosity and density, and their variation with temperature and pressure; chemical and toxic effects; bulk modulus or compressibility; water miscibility, and the significance of cloud, pour, and boiling points. The fire hazard, and its difficulties of assessment in relation to the usual recorded properties and conditions, is noted. Thermal conductivity, dielectric strength and storage conditions are also considered. Some of the information, of which much hitherto has been widely scattered, has been derived from recent research, and an attempt has been made to arrange the data in rational form.