A pressure control device for a milking machine comprises a housing (1), a vacuum inlet (2), and two control circuits (3a, 3b). Each circuit comprises a main vacuum passage (4) extending through the housing from the vacuum inlet to an outlet (5), and including a main valve (6) configured to take one of an open position and a closed position. A pilot passage (7) extends from the main vacuum passage and includes a pilot valve body (8) configured to take one of an open pilot position and a closed pilot position. The pilot passage acts in the open pilot position on the main valve to move to the open position, and permits in the closed pilot position the main valve to move to the closed position. A solenoid (9) controls the pilot valve body. A holding member (10) receives the solenoid and is attached to the housing through a first bayonet coupling.