What are the two most important properties of a hydraulic fluid?

Viscosity and cleanliness are indeed the most crucial properties of hydraulic fluid for several reasons related to the performance and reliability of hydraulic systems.

Viscosity is paramount because it directly influences the fluid's ability to create adequate pressure and provide lubrication in hydraulic circuits. A fluid with the proper viscosity ensures effective operation under varying temperature conditions and load demands, leading to improved efficiency and minimized wear on components such as pumps, valves, and actuators.

Cleanliness is equally significant since contaminants in hydraulic fluid can cause malfunctions, reduce component lifespan, and lead to system failures. Maintaining a low level of particulates, water, and other impurities ensures that the system operates smoothly and reliably, preventing damage and the need for costly repairs or replacements.

These two properties are essential for ensuring the hydraulic system's performance, efficiency, and longevity, making them the most important characteristics to consider in hydraulic fluid selection and maintenance.