The drive shaft is rigidly held in the pump housing by a large tapered roller bearing at the rear of the shaft and a smaller bearing at the front of the shaft. Set between another pair of large bearings is a fixed-angle cam or wobble plate.
As the drive shaft turns, the wobble plate nutates, oscillating forward and back (converting axial motion into linear motion). The complete pumping mechanism is submerged in a lubricating oil bath.
