Gears
The gear pump uses two identical gears rotating against each other. One gear is driven by a motor and it in turn drives the other gear. Each gear is supported by a shaft with bushings on both sides of the gear.
Drive Gear (Rotor)
The drive gear in the gear pump is the gear that is driven by the motor.
Idler Gear
The idler gear is the gear that is driven by the drive gear.