Which design is NOT typical for gear pumps?

Gear pumps are typically characterized by their mechanism that uses gears to pump fluid by displacement. Among the designs associated with gear pumps, external gear and in-line designs are quite common, as they feature intermeshing gears that create a sealed cavity, allowing fluid to be drawn into the pump and expelled under pressure.

Furthermore, rotary pumps can also include gear configurations; however, they may refer to different types of rotary mechanisms that are not strictly confined to gears alone.

The vane type design, on the other hand, employs vanes that slide within a rotor and represents a different operational principle, as it does not utilize gears for fluid movement. Each of these alternatives demonstrates attributes distinct from those of typical gear pump designs.

Thus, the concept of a "rotary" pump can encompass both gear and non-gear configurations, leading to the conclusion that the vane type is notably outside the typical parameters for gear pumps. The correct choice highlights a design that fundamentally differs in operation, thereby reinforcing the clarity of what constitutes a gear pump mechanism.