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This paper summarizes the results and findings of a program to design, develop, and evaluate actuator rod seals for use in advanced aircraft high-temperature hydraulic systems. The rod seals are intended to function efficiently and reliably for 3000 hr in the temperature range of -40-500 F. Preliminary studies of various material and design combinations showed that a polyimide low-pressure second-stage V-seal in a two-stage configuration had the greatest potential in long-term duty cycle testing in a simulated actuator test system. Modifications of this seal that provided for improved fatigue life and more efficient loading met the test objectives of 20 X 106 short-stroke cycles of operation at 500 F. Severity of this testing was equivalent to 3000 hr of duty cycle operation. The validity of design techniques used to achieve performance goals was shown.

This paper concerns the design, development and evaluation of metallic seals to meet the extreme conditions of temperature and pressure experienced in fluid power systems of advanced aerospace vehicles. The basic principles and design problems that characterize the use of metallic seals are discussed. Single and two-stage rod seals for 4000 psi, -65 F to +1000 F, hydraulic system applications using mineral oil and polyphenyl ether fluids are described. The performance evaluation of metallic and graphite piston rings are included. The selection of rod-gland material combinations and surface coatings are discussed. Static seal configurations for use at 4000 psi and temperatures up to 1000 F are also described.