Compressibility of hydraulic oil is very significant for large diameter cylinder presses, especially if they are exposed to high pressures. The paper presents a theoretical analysis of the process of compression and decompression of oil in the cylinders with and without the presence of air presenting an analog model. Although considerations are relating to the ideal conditions of the process of compaction, the paper defines the basic mathematical processes depending on compression and discharge of the same. They refer to the definition of the time discharge and elimination of adverse effects in the same.
