The invention relates to a variable displacement pump (1, 100) for hydraulic gearbox control systems, in particular a vane pump, having a variable stroke volume and having a pump regulator for outflow pressure regulation, in which the outlet pressure of the pump acts in a compensation chamber (9) and a regulation pressure, which can be set by the pump regulator, acts in a regulation pressure chamber (11, 106) on an adjustable stroke ring (3, 105), wherein the pressure in the regulation pressure chamber (11, 106) and an additional spring force adjust the stroke ring (3, 105) in the direction of maximum pivoting out; and having a gearbox control system for automatic gearboxes, which has a primary hydraulic circuit (39, 130) for the elements of the gearbox that are relevant to force transmission and a primary pressure regulating valve (41, 134, 212), which opens a bypass to a secondary hydraulic circuit (55, 136, 218) when the settable primary pressure is exceeded and has an additional pressure-limiting function for the primary pressure if the primary pressure continues to be exceeded, and wherein the secondary hydraulic circuit (55, 136, 218) acts to cool and lubricate the gearbox, and wherein the regulation loop or regulation circuits of the pump regulation system and of the gearbox regulation system can be separated from each other by a switching valve (138, 170, 184, 200) and thus can be connected individually and independently or can be connected together.