needed if a pulling load is present at a hydraulic motor in an open circuit. Since what had been the pressure line then becomes the suction line, the servo-suction valve is intended to prevent a vacuum forming in this line by suction oil from the container. Servo-suction valves are mainly used in winch drives, as well as for cylinders in a half open hydraulic circuit.
Normally with cylinder drives with a pulling load, throttling is performed at the side with the piston load until a balance is reached with the load.