Below is a list of Hydraulic Cylinder Seals manufacturers from Saint Charles, Illinois. Hydraulic cylinder seals are tools used to maintain pressure levels in hydraulic cylinders; they are crucial to the safety and efficiency of a functioning hydraulic cylinder. Hydraulic cylinders produce linear motion by using pressurized fluid. They vary in design, size and material according to the pressure and temperature requirements, but most hydraulic seals used in cylinders are shaped similar to o-rings but with a more complex profile.