Device for sampling and dispensing adjustable volumes of liquid, with numerical display

A device for sampling and dispensing adjustable volumes of liquid samples, comprising an upper housing, a substantially cylindrical lower body secured to the upper housing, piston means movable reciprocatingly in the lower body, adjustable stop means limiting the travel of the piston means, means resiliently urging said piston means into contact with said adjustable stop means, a control rod which passes through the housing, and pushbutton means at the upper end of said control rod, wherein the improvement comprises a mechanism to adjust the position of said stop and to display the corresponding sample volume, said mechanism comprising:

• an externally threaded sleeve which is capable of cooperating by screw action with an internal thread of the housing and whose lower end constitutes said adjustable stop, said control rod comprising a prismatic control rod and passing through said sleeve and having a profile such that said rod rotates with the sleeve, while permitting a relative sliding of said rod in relation to said sleeve;
• a bush mounted to rotate freely in the upper part of the housing, and coaxial with the sleeve;
• means for causing said bush to rotate with the control rod, said means removably securing said bush to said rod;
• said bush including an inner opening with a diameter of a size to enable said sleeve to penetrate into said bush,
• a plurality of volume-indicator drums surrounding said bush in such a way that the units drum rotates with the bush, the other freely rotating drums being equipped with drive means capable of controlling the relative movement of the drums in dependence on the movement of the bush, the sleeve and the control rod rotating as a unit.