Control device adapted to control at least two DC-machines (400, 500) of a railway vehicle, each DC-machine (400, 500) having a field winding and an armature winding, the control device comprising - a voltage supply circuit having a first supply circuit terminal adapted to be electrically connected to an electrical DC power source, a second supply circuit terminal adapted to be connected to a ground potential, the voltage supply circuit being adapted to regulate an electrical power exchange between the electrical DC power source and the at least two DC-machines (400, 500), the voltage supply circuit comprising: - a common first switching module with ∘ a first switch having a first switch terminal electrically connected to the first supply circuit terminal and a second switch terminal electrically connected to a third supply circuit terminal, and ∘ a second switch having a first switch terminal electrically connected to the third supply circuit terminal and a second switch terminal electrically connected to the second supply circuit terminal; and - for each DC-machine: - at least one second switching module having ∘a first switch having a first switch terminal electrically connected to the first supply circuit terminal and a second switch terminal electrically connected to a fourth supply circuit terminal (8, 9) adapted to be connected to a first armature winding terminal (412, 512) of the armature winding (410, 510) of the respective DC-machine (400, 500), and ∘a second switch having a first switch terminal electrically connected to the fourth supply circuit terminal (8, 9) and a second switch terminal electrically connected to the second supply circuit terminal, and - for each DC-machine (400, 500) a current rectifying unit (430, 530) having two output terminals (432, 434; 532, 534) adapted to be connected to the field winding (420, 520, 520') and two input terminals (436, 438, 536, 538), a first input terminal (436, 536) being adapted to be electrically connected to a second armature winding terminal (414, 514) of the respective DC-machine and a second input terminal (438, 538) being adapted to be electrically connected to the third supply circuit terminal. - a voltage supply circuit having a first supply circuit terminal adapted to be electrically connected to an electrical DC power source, a second supply circuit terminal adapted to be connected to a ground potential, the voltage supply circuit being adapted to regulate an electrical power exchange between the electrical DC power source and the at least two DC-machines (400, 500), the voltage supply circuit comprising: - a common first switching module with ∘ a first switch having a first switch terminal electrically connected to the first supply circuit terminal and a second switch terminal electrically connected to a third supply circuit terminal, and ∘ a second switch having a first switch terminal electrically connected to the third supply circuit terminal and a second switch terminal electrically connected to the second supply circuit terminal; and ∘ a first switch having a first switch terminal electrically connected to the first supply circuit terminal and a second switch terminal electrically connected to a third supply circuit terminal, and ∘ a second switch having a first switch terminal electrically connected to the third supply circuit terminal and a second switch terminal electrically connected to the second supply circuit terminal; and - for each DC-machine: - at least one second switching module having ∘a first switch having a first switch terminal electrically connected to the first supply circuit terminal and a second switch terminal electrically connected to a fourth supply circuit terminal (8, 9) adapted to be connected to a first armature winding terminal (412, 512) of the armature winding (410, 510) of the respective DC-machine (400, 500), and ∘a second switch having a first switch terminal electrically connected to the fourth supply circuit terminal (8, 9) and a second switch terminal electrically connected to the second supply circuit terminal, and ∘a first switch having a first switch terminal electrically connected to the first supply circuit terminal and a second switch terminal electrically connected to a fourth supply circuit terminal (8, 9) adapted to be connected to a first armature winding terminal (412, 512) of the armature winding (410, 510) of the respective DC-machine (400, 500), and ∘a second switch having a first switch terminal electrically connected to the fourth supply circuit terminal (8, 9) and a second switch terminal electrically connected to the second supply circuit terminal, and - for each DC-machine (400, 500) a current rectifying unit (430, 530) having two output terminals (432, 434; 532, 534) adapted to be connected to the field winding (420, 520, 520') and two input terminals (436, 438, 536, 538), a first input terminal (436, 536) being adapted to be electrically connected to a second armature winding terminal (414, 514) of the respective DC-machine and a second input terminal (438, 538) being adapted to be electrically connected to the third supply circuit terminal.