摘要 |
<p>A variable displacement pump (3) comprises a piston (4) reciprocable within a cylinder (2), a displaceable inlet valve (5) adapted to control admission of lower pressure hydraulic fluid (9) to the swept volume area (10) of the piston (4) and cylinder (2), a displaceable outlet valve (7) adapted to control delivery of higher pressure fluid (9) from the swept volume area (10), and means (13, 13A, 26-28, 29-44) to control the position of the inlet valve (5) so as to control the volume of fluid (9) delivered by the pump (3) in accordance with demand.</p> |