What type of pump is designed with an eccentric motor within the casing?

A sliding vane pump is designed with an eccentric motor within the casing. This design feature allows for the use of sliding vanes that extend and retract as the rotor turns, creating chambers that fill and discharge fluid. The eccentricity of the motor creates an oscillating motion, which facilitates the sliding action of the vanes against the inner wall of the pump casing. This results in a continuous flow of fluid, making sliding vane pumps particularly useful for applications where a constant and smooth flow is required.

In contrast, gear pumps rely on meshing gears to facilitate fluid movement, while centrifugal pumps use a rotating impeller to increase the velocity of the fluid. Piston pumps utilize reciprocating motion to move fluid. The unique mechanism of the sliding vane pump, characterized by the eccentric motor and sliding vanes, directly distinguishes it as the correct answer for this question.