A roller vane pump for fluid includes a carrier which is rotatable in a
housing about an axis of rotation, the carrier carrying a plurality of
roller vanes which are each received in a respective slot which extends
inwardly of a periphery of the carrier and permits the roller to move
inwardly and outwardly in use, the housing surrounding the carrier,
pumping chambers being formed between the rollers, the carrier and the
housing, the rollers engaging with the housing and moving inwardly and
outwardly of their respective slots as the carrier rotates, in response
to the configuration of the housing so that the pumping chambers change
in volume as the carrier rotates, to effect pumping of the fluid, from an
inlet to an outlet of the pump, and wherein in each of the slots in which
the rollers are received, there is provided a restrictor element which
restricts movement of the roller inwardly of its respective slot.