[41] Internally toothed gear pump
The inner gear is driven by
a motor. The teeth of the inner wheel drive the outer gear wheel.
The rotary motion creates a vacuum in the gaps between the teeth,
causing hydraulic fluid to be sucked in. On the other side, the
teeth engage once more and oil is displaced from the tooth
chambers.
The design can deliver pressures of up to approx. 17.5 MPa (175 bar). Hydraulic motors represent the reverse of the function principle.