To provide a supplying means for a pressure medium in a brake system achieving a desired pressure level in a settable period of time, particularly, a forming and/or adapting method for an operating signal for pump operation.

The operating signal U of a pump 100 in a brake system is formed as the function of pressure gradient Pg from an accumualtor 104. The input time Tein in the operating cycle TAKT of a pulse width modulating signal for the pump operation is changed after considering the pressure gradient of the accumulator. This is carried out by a control unit 107 through response from a switching means 103. The operation as the function of the pressure gradient Pg carries out an alternative operation as the function of a generated voltage Ugen or by the combination with that of the pressure gradient.