What is typically used to drive the rotors in an unbalanced vane pump?

In an unbalanced vane pump, the rotors are typically driven by a splined shaft. This design allows for efficient power transfer from the motor to the pump's rotor assembly, accommodating any slight misalignments that may occur during operation. The splines ensure a secure and positive connection, allowing the rotor to maintain consistent engagement with the power source while minimizing wear and providing a reliable means to handle the torque generated during the pump's operation.

The other options do not serve the same purpose in the context of unbalanced vane pumps. A piston rod is commonly associated with reciprocating mechanisms, banjo fittings are used for fluid connections, and connecting links are generally part of chain drives or other mechanical linkages but do not apply to the driving mechanism of the rotors in this type of pump.