Abstract: A technique for producing flexible tubing for use in hydraulic systems employing non-combustible, force-transmitting liquids is described. An inner layer of the tube is formed from a load-carrying metal insert embedded in polychloroprene or natural rubber, which forms a good bond therewith. The exterior, liquid-contacting layers of the tube are formed from ethylene-propylene-terpolymer (EPDM) rubber, which withstands penetration by the hydraulic liquid. A good bond between the interior and exterior layers is provided by an intermediate layer formed from an EPDM-polychloroprene or EPDM-natural rubber mixture, the EPDM constituent being present in a proportion of about 50-80%. The transition layer may be embedded with a polymer-impregnated textile, either of cotton or of a synthetic substance such as rayon, polyamide or polyester.