A linear pump includes a housing having a bore and axially spaced apart inlet and outlet. A first check valve is joined to the housing for controlling flow of fluid through the bore. A piston is disposed coaxially in the housing bore for axial translation therein and includes a piston bore and axially...http://www.google.de/patents/US5924975?utm_source=gb-gplus-sharePatent US5924975 - Linear pump
