Manually operated pump

Abstract

A manually operated pump (), comprising a cup-shaped body () inside which a piston ()—coupled with a hollow stem () for the movement thereof within the cup-shaped body ()—sealingly slides, the pump being equipped with a base () which seals the cup-shaped body () and which is endowed with a hole () for the stem (), the said stem () and the base () being torsionally coupled, at least part of the cup-shaped body () and of the piston () delimiting a compression chamber () coupled with at least one suction valve element () and with a delivery valve element (), the said delivery valve element () being in communication with a cavity in the stem (), a dispensing button () being sealingly fitted on the stem (), the said button () and the stem () being mutually constrained so that the button rotates, in a limited manner, around an axis (A) of the stem () between a first dispensing position and a second closed position, in which at least one tooth (D) of the button abuts a surface () of a ring nut () so as to prevent a stem () stroke; the ring nut () can be coupled torsionally to the base () or to the cup-shaped body () in at least two alternative assembly positions, such that, if the ring nut () is in its first assembly position and the button () is in the dispensing position, a first groove (S) of the ring nut faces the tooth (D) which can slide in it up to a first end-stroke (F), allowing a first stroke of the stem () and which, if the ring nut () is in its second assembly position and the button () is in the dispensing position, a second groove (S) of the ring faces the tooth (D) which can slide in it up to a second end-stroke (F), allowing a second stroke of the stem () different from the first stroke of the stem, so that, during the assembly of the pump, the positioning of the ring nut () in the first or second assembly position () determine a first or second dispensing volume of the pump.