A machine (M) for preparing beverages, in particular espresso coffee, comprises a hydraulic circuit, which includes: —a brewing unit (1), comprising at least one first part (1a) and one second part (1b), which are able to define between them a brewing chamber, at least the first part (1a) being movable with respect to the second part (1b); —a fluid actuator (12), in particular a hydraulic actuator, which can be supplied for causing at least a displacement of the first part (1a) of the brewing unit (1) towards the second part (1b); —a water tank (4); —a pump (3) having the inlet connected in fluid communication with the water tank (4) and the outlet or delivery connected in fluid communication with the brewing unit (1) and to the fluid actuator (12); —at least one normally closed unidirectional hydraulic valve (9′), set between the pump (3) and the brewing unit (1), to enable a flow of water towards the brewing unit (1) when the pressure of the water delivered by the pump (3) exceeds a substantially pre-set threshold; —a heater device (8) for heating the water delivered by the pump (3); and —a normally open discharge valve (10′), which has: a main inlet (10IN), connected to the fluid actuator (12); a main outlet (10OUT) connected towards a collecting space, in particular the water tank (4); and a valve member set between the main inlet (IOIIM) and the main outlet (10OUT) able to assume an open condition and a closed condition, where it enables and prevents, respectively, a flow of fluid between said main inlet (10IN) and said main outlet (10Oντ) The discharge valve (10′) is a hydraulically driven valve, which further comprises a driving chamber, for hydraulic driving of the valve member, an auxiliary inlet (10DR-IN) of the driving chamber, connected to the delivery of the pump (3), and an auxiliary outlet (10DR-OUT) of the driving chamber (26), connected to the brewing unit (1) and to the fluid actuator (12), in such a way that water delivered by the pump (3) passes through the driving chamber (26) before reaching the brewing unit (1) and the fluid actuator (12).
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