outer face portion 1724 for axial reciprocal movement along the inner face 1715 of cylindrical and relatively fitting configuration spring 1718 in spring seat 1717 presses the flow control member 1716 downwards but the snap ring 1725 is provided to prevent an excessive extend of the stroke of the passage valve 1716 the passage valve 1716 has a front head face and a rear face with its rear face it touches the upper housing 39 s front face for prevention of excessive upwards movement the passage valve 1716 is shown in its closing position which is the uppermost location the front face aligns with the bordering face 1513 of the inner chamber 37 at this position and location of the control valve whereby the control valve forms with its front head face a portion of the stroke restricting border face 1513 the front portion of valve 1716 has rearwards an inclined narrowing face and portion 1721 which is radially surrounded by a ring shaped annular space 1723 which space is formed into guide body 1 by the outwardly tapered face and portion 1722 from space 1723 extend substantially axially directed passages 1719 into the end space 1714 while in fig1 the important passage control member 1716 is shown in its closed position the opened location of the passage control valve is seen in the bottom portion of fig2 there the passage valve is moved downward to its downward most location at which the snap ring 1725 touches the bottom face 1761 of the rear space 1714 this touching prevents any further downwardly directed movement of the passage control valve 1716 it is seen in this figure portion that the inclined face 1721 has now moved far away from the inclined face 1722 of the guiding body a relatively.