Gear Metering Systems
Gear pumps are the core of any gear system. They are based on the Archimedes' principle and differ from any of the delivery and metering systems mentioned below by the fact that they do not require any control elements. This means that no automatic or controlled valves are required - neither for the delivery process itself nor for determining the delivery direction.
The gear pumps used in metering and mixing systems are mainly based on two externally toothed gears of equal size (in case of very small types also internally toothed versions). The gears are located in a housing which features very little clearance between its walls and the gear.