Hydraulic power steering Is an auxiliary system that uses the #engine #power to change the angle of the wheel axis and thus change the direction of the #car by the hydraulic pressure provided by a hydraulic pump driven by the vehicle’s engine .

#Hydraulic #pump is a mechanical source of power that converts mechanical power into hydraulic energy (hydrostatic energy i.e. flow, pressure). It generates flow with enough power to overcome #pressure induced by the load at the pump outlet.
There is a multiple designs for the hydraulic pump
the #gear hydraulic pump is a simple effective design and cheap