ABSTRACT
Hydraulic fluid has four functions: (1) transmit power, (2) lubricate, (3) seal clearances, and (4) provide cooling. This chapter discusses how to maintain the fluid properties needed for the three additional functions. Control of fluid properties provides extension of component life and reduction of unscheduled downtime.
Temperature control provides viscosity control. It is recommended that a hydraulic system be designed for a maximum operating temperature of 60°C. Proper viscosity ensures that fluid will flow into clearances and establish the needed lubricating film and then seal these clearances to prevent excessive leakage.
Proper selection and placement of contamination control devices will eliminate up to 80% of all system failures. Sources of contamination are built-in, contaminated new oil, ingressed, and internally generated. Once a target cleanliness level has been set, and the filters have been selected and located in the system, a monitoring program is put in place to ensure the target cleanliness level is maintained
