Hydraulic seals can be static or dynamic in wireline equipment, depending on their function. Static seals prevent leakage between non-moving parts, while dynamic seals isolate sections that move relative to each other, such as between the wireline and sealing head assembly. Both designs must compensate for potential movement, pressure surges, and cable flexing.​ https://globalsealstech.com/product-category/oil-gas-seals/oil-free-lubricated-pump-seals/