Abstract: A switchable mechanical motor vehicle coolant pump includes a rotatable drive shaft, a drive wheel, a coolant pump wheel comprising a radially outer outlet, a control slider, and an actuation system which hydraulically actuates the control slider. The drive wheel and the coolant pump wheel are each connected to the drive shaft. The control slider shifts axially with respect to the coolant pump wheel to at least partially close the radially outer outlet. The actuation system includes pressure chamber(s), an auxiliary pump having an auxiliary pump wheel provided integrally with the coolant pump wheel, and a switchable control valve which controls a pressure level within the pressure chamber(s). The auxiliary pump wheel provides a hydraulic actuation pressure for the pressure chamber(s) and comprises a ring-shaped pumping channel in which pumping vanes are arranged equidistantly along a circumference of the ring-shaped pumping channel so as to define equal pumping chambers therebetween.

Abstract: A coolant pump for providing a coolant to an engine includes a pump frame, a rotatable rotor shaft, a pulley wheel co-rotatably fixed to the rotor shaft, an axially shiftable ferromagnetic rotatable pump wheel, and an electromagnetic wet friction clutch arrangement. The pump wheel is axially shiftable with respect to the rotor shaft and the pump frame. The clutch arrangement comprises a static electromagnet, a clutch disk co-rotatably supported by the rotor shaft, a first clutch friction surface arranged at the clutch disk and a thereto corresponding second clutch friction surface arranged at the pump wheel, and a separate stop friction surface arranged at the pump wheel and a thereto corresponding static stop friction surface arranged at the static pump frame. The electromagnet, when fully energized, axially attracts the pump wheel so that the separate stop friction surface and the static stop friction surface engage to stop the pump wheel.