A vane pump is disclosed for use with gas turbine engines which has
pressurized fluid supplied to the undervane portion of the vane elements
to balance the forces imparted thereon. The vane pump includes a pump
housing, a cam member, a cylindrical rotor member and a chamber. The
chamber is defined within the housing and positioned for fluid
communication with the undervane portion of each vane element to provide
a desired pressure thereto. The chamber is in fluid communication with a
first pressure source and a second pressure source, wherein the first
pressure source is associated with the discharge arc segment of the
pumping cavity, and the second pressure source is associated with the
inlet arc segment of the pumping cavity.