Abstract: Tubing for a brake system, fuel system or hydraulic system in automotive vehicles which includes an inside steel tube having an outer surface, a zinc coating layer on the outer surface, chromated layer overlying the zinc coating layer and a plastic jacket layer overlying the chromated layer wherein the plastic jacket layer is composed of a polyamide on the chromated layer, the polyamide preferably being laurinlactam and the chromated layer preferably being olive-colored. The method of tubing manufacture including the steps of heating a steel tube having an outer surface with the zinc coating and chromate present thereon to an elevated temperature; the elevated temperature being within about .+-.30.degree. C. of the extrusion temperature of polyamide material to be applied to the tube; extruding polyamide material onto the surface of the heated tube; and quenching the tube in a liquid bath after the polyamide has been applied.

Abstract: A flow control valve for controlling liquid flow, for example, water flow in a vehicle heating circuit, has a ceramic obturator plate which slides sealingly relative to a fixed sealing plate, the two plates having openings the degree of overlap of which determines the valve throughflow. A bowed leafspring maintains the slidable obturator plate in sealing contact with a mating face of the sealing plate.