Reaching negative pressure difference in model of pump and hydraulic cylinder.

Hey, I'm stuck on achieving a negative pressure differential from the valve to the T-pipe. The point is, I'd like to design a system where the pump drives the actuator and lowering the actuator drives the shaft, so that the pump runs in drive and generator mode. At present, the negative signal on the valve causes the T-channel to work only as an overflow. . . What should be done to achieve a negative differential pressure to drive the pump? Of course, I am aware that this involves a modification of the current system at the place where the pump is driven by a clutch and the reception of the shaft torque.

Best regards, Jakub