Clark Seals was engaged to address a transmission seal failure occurring after approximately 250 hours of operation. Upon analyzing the application, several operational challenges were identified. The vertical input shaft operated under varying pressures up to 60 psi and was housed within a long tubular casing that left little space for a standard seal design. Additionally, the seal needed to be installed in either direction without damaging the sealing lip. The shaft had an end play of 0.015", which fell outside the typical design envelope, and the seal would occasionally experience sparse lubrication.

Traditionally, pressure seals were designed with a thick flex section and a stubby beam length, featuring reduced lip interference and a smaller lip force contribution from the garter spring. The cavity pressure would push the fragile rubber lip against the sealing surface, and the combined lip force from the rubber and internal pressure would squeeze out the lubricant between the lip and sealing surface. As the shaft rotated, friction increased, causing the lip to follow the shaft, leading to lip tear and premature seal failure. The previous pressure seal design, with its thicker net section, aimed to resist lip distortion and prevent increased lip force due to internal pressure.