This oil reservoir supplies the pump with a steady volume of hydraulic fluid during spraying operations. It sits between the tank outlet and the pump inlet, maintaining a positive head to prevent cavitation at the pump's suction port. A drop in fluid level in the reservoir indicates a restriction or leak upstream, which can lead to pressure fluctuations at the nozzles. The reservoir is constructed by Udor to match the port geometry of the pump housing, ensuring a sealed connection without additional adapters.