| 摘要 |
<p>At its opposite ends, the piston has annular seals which, in a cleaning position of the piston, are located in respective separated zones of the cylinder where its internal diameter is greater than the diameter of the seals, so that cleaning liquid from an inlet opening of the cylinder can be forced directly into one of these zones, thence to the other zone by way of a longitudinal recess in the piston, and then through an outlet opening of the cylinder, whereby the two seals are flushed. Limiting means are provided which, during normal reciprocation of the piston, prevent it from moving to this cleaning position but which are adjustable to permit such movement when cleaning is desired.</p> |
