| 摘要 |
A pump including a head (10) and a cylindrical tube (34) extending from the head, an axially movable plunger (40) being accommodated in the tube and having a piston rod (42) extending through a guide means (36) in the head (10), the cylindrical tube (34) externally being surrounded by a tubular envelope (16), such that between the cylindrical tube and the envelope is formed a space (52) communicating with the interior of the cylindrical tube as well as with connecting means (19, 23) for supply and discharge, respectively, of fluid. The connecting means is provided with one check valve (20, 24) each and each check valve is turnable for reversing the relative flow direction of the associated connecting means such that the connecting means for supply of fluid becomes connecting means for discharge and the connecting means for discharge becomes connecting means for supply of fluid. |
