Gear pump is another type. It uses the meshing of two gears to move hydraulic fluid across the pump. The simplest type of two stage hydraulic pump is the external tooth gear pump, which is made up of a pair of meshing gears whose rotation pulls fluid around their outside circumference. And different materials can be used depending on the application.
Then let us look at the rotary vane pumps. When compared to gear pumps, they have higher efficiency at the expense of greater mechanical complexity. The heart of it is an off-center cylindrical rotor up against the side of a cavity into which the fluid to be pumped is introduced. The cylindrical rotor has two wings which extend from its sides under pressure of a spring inside the rotor.
Although various types of hydraulic pumps have some common components, they still have much difference according to different modes of operation. For example, 12 volt hydraulic pump motor are typically made up of a pair of intermeshed screws that rotate together inside of a metal housing. They generate low noise levels and have fewer moving parts that are susceptible to wear and damage, but also have a lower efficiency than other types.