Variable delivery, fixed displacement pump

A method for controlling the delivery rate of a fixed displacement pump having a rotatable, angled swash plate drivingly connected with at least one piston to thereby move said piston through a reciprocal stroke within a cylinder defined by a cylinder block axially spaced from said swash plate, said piston and cylinder together defining a fluid compression chamber having a delivery outlet, said method comprising:

• providing a vent port from said fluid compression chamber operable to vent fluid from said compression chamber during at least a portion of the reciprocal stroke of said piston, said piston and cylinder cooperating to close said vent port during another portion of the reciprocal stroke of said piston so that fluid within the compression chamber is pumped through the delivery outlet;
• and
• providing relative axial motion between said swash plate and said cylinder block to adjust the axial spacing between said swash plate and said cylinder block, wherein the axial spacing between said swash plate and said cylinder block determines the duration of said another portion of the reciprocal stroke of said piston.