Analysis and design of hydraulic cylinder seals

Abstract: Hydraulic cylinder seal performance is studied experimentally and theoretically. The seal performance is discussed in terms of friction force and oil leakage, which are due to the oil film build-up in the seal contact. The theoretical analysis is based both on calculated and measured contact pressure distributions. The compressibility of seal materials is determined experimentally, and it is shown that the compressibility is a pressure dependent material property. A method for calculation of the contact pressure distribution for a seal with an arbitrary cross-section is proposed, based on geometrical considerations and the experimentally determined compressibility. The pressure calculations are verified experimentally. Theoretically calculated oil film thicknesses in a seal contact are compared with measured film thicknesses. The increase of film thickness with increasing sliding velocity shows a good agreement between theory and experiment. The oil film is thicker in the experiments due to the surface roughness of the seal. A complete theoretical analysis of the seal performance is developed to be used as a design tool.