Abstract: A positive displacement fluid pump capable of an output flow rate can be varied from a maximum to zero at a given pump rotation speed. The pump is a variable-fluid-displacement-volume, gear pump having complement elements associated with pumping gears to provide end seals for a variable-length pumping chamber. A timing arrangement maintains both pumping gears always in synchronization, whether engaged or fully disengaged (zero pump output). And a follower provides effective sealing with a movable face of an axially-translating pumping gear.