Switchable mechanical coolant pump

A coolant pump includes a rotatable rotor shaft, a pulley wheel which co-rotates with and is supported by the rotor shaft, a pump wheel rotatably supported at the rotor shaft, and an electrically switched wedge-coupled wet friction clutch. The wedge-coupled wet friction clutch comprises a clutch support fixed to the rotor shaft, a clutch ring arranged at a proximal side of the pump wheel, a clutch disk comprising a ferromagnetic element, a static electromagnet which axially pulls the clutch disk to the clutch support into a disengaged position when the static electromagnet is energized, and a wedge coupling mechanism. The wedge coupling mechanism comprises a wedge element and a counter-wedge element which are configured to generate an axial wedge force which axially pushes the clutch disk into an engaged position against the clutch ring when the static electromagnet is not energized and the rotor shaft rotates.