in these figures , corresponding elements are designated by the same reference numerals , sometimes provided with an index . the respective dimensions and proportions of these elements are not necessarily respected in order to render the drawings more clear . the pump according to the invention represented in fig1 to 8 of the drawings mainly comprises a pump body 1 in which is slidable a piston 2 under the action of a manual push - member - distributor 3 . the pump body 1 is enlarged at its open end by a flange 4 inserted in an annular cavity 5 of a screw - threaded cap 6 to be fixed to the neck of a container ( not shown ) which has a corresponding screw thread . the skirt of the cap defines a step 7 which is cooperative with an abutment of the neck of the container for angularly determining , in the conventional manner , the position of the cap with respect to the container at the end of the screwing . the cavity 5 of the cap also encloses an end flange 8 of a ring 9 whose inner wall defines , recessed therein , two ramps 10a , 10b which are in the shape of an arc of a circle and are diametrically symmetrical and each limited at the upper end respectively , at the end of a horizontal planar part 40a , 40b , by an abutment 11a , 11b , each ramp opening respectively at the lower end onto a longitudinal groove 12a , 12b . the upper end of the ring is surrounded by a ledge 13 and the lower end includes in proximity to the flange 8 two symmetrical ribs 14a , 14b which have the shape of an arc of a circle and are adapted to clip over or engage by a detent action the upper wall of the cap 6 under which the flange 8 is inserted . two groups of deformable diametrically symmetrical lugs 15a , 15b project from the flange 8 against the lateral wall of the ring 9 . these lugs , when the ring is forced into the axial opening of the cap 6 until the clipping or detent action occurs , deform and block the ring in the cap at the chosen orientation which is indicated , on one hand , by a flat face 16 on the flange 8 of the ring , and , on the other hand , by a recess 17 in the upper face of the cap 6 . the manual push - member - distributor 3 is radially extended in its upper part by a nose - shaped nozzle 17 which opens onto , through a narrowed part 33 acting as an annular abutment for the head 34 of the piston 2 , an axial cavity 18 which freely receives the open end portion 19 of the tubular piston 2 in which is movable a delivery valve ball 20 . the blind cavity 18 is extended by a cylindrical part 21 of larger diameter which receives in a sealed sliding manner an annular marginal lip 22 extending from the piston 2 . the piston 2 terminates in two stepped annular lips 23 , 24 which are slidable in the pump body 1 . an axial rod 25 disposed in the pump body 1 maintains at the bottom end a suction valve ball 26 and its base acts as a support for a return spring 27 for returning the piston to the upper position . the enlarged free end of the rod 25 is cooperative with an inner shoulder 28 of the piston 2 for ensuring the sealing of the pump at rest merely under the effect of the pressure exerted by the spring 27 . this shoulder 28 is reinforced by internal radial ribs 29a and 29b . other external radial ribs 30 in supporting relation to the lip 23 reinforce the piston and are cooperative , for ensuring a free guiding of the piston , with an inner annular bearing surface 31 in the ring 9 . the stepped lips 23 , 24 cooperate in a conventional manner with a lateral port 32 in the pump body 1 for sealing the pump , and consequently the container , at rest and for putting the interior of the container in communication with the atmosphere when the piston 2 is depressed . the outer surface of the wall defining the axial cavity 18 , 21 of the push - member - distributor 3 defines two diametrically opposed radial ribs 35a , 35b whose end faces of the free ends cooperate , in the manner of lugs , with the ramps 10a , 10b and the grooves 12a , 12b of the ring 9 for blocking or for allowing the depression of the push - member 3 and consequently the piston 2 . two small ribs 36a , 36b of the ring which are capable of being overcome cooperate with the flanks of the radial ribs 35a , 35b of the push - member to avoid any involuntary rotation of the push - member 3 when it is in the blocked position . the push - member 3 also comprises an internal median skirt 37 terminating in an inner bead 38 which cooperates , after an elastic clipping or detent action , with an outer bead 39 on the top of the ring 9 for preventing the push - member from escaping from the ring , and consequently from the pump , while allowing it full freedom to rotate and to be depressed . the pump further comprises an ornamental outer sleeve 41 which extends upwardly and downwardly beyond the cap 9 and overlaps the free end of the push - member - distributor 3 . inner radial ribs 42 of the sleeve bear against the upper face of the ring 9 to ensure a good positioning of the sleeve when it is mounted with force on , or is adhered to , the cap 3 . owing to this structure , it is possible to mass - produce , irrespective of its particular commercial destination , the whole of the mechanism of the pump . at the moment of assembling the ring in the cap , the desired orientation is chosen . the personalization of the pumps is achieved merely by the choice of the decoration of the sleeve and , possibly , of the push - member . all the elements are easily produced from molded plastics materials , the sleeve being possibly of metal or other material such as wood or leather . in the embodiment shown in fig1 to 8 , the user brings the pump from the blocking position in which the piston cannot be depressed , to the position of use , and inversely , merely by rotating the push - member - distributor through 90 °. the ring 9 &# 39 ; having a single ramp 10 &# 39 ; of the variant shown in fig9 to 14 is inserted in a pump similar to that shown in fig1 with a push - member which has only a single rib 35 . the single ramp 10 &# 39 ; in the shape of an arc of a circle opens onto a longitudinal groove 12 &# 39 ; and terminates at the upper end in a horizontal planar part 40 &# 39 ; leading to an abutment 11 &# 39 ; which is twice as long as the planar parts 40a , 40b of the ring 9 of the fig2 to 7 . with this variant , the distributor nozzle 17 of the push - member occupies , by rotation through 180 °, two diametrically symmetrical positions , namely a blocked position and a position of use respectively , which may be an aesthetic advantage with certain forms of containers . on the other hand , with other forms , in particular with flat containers , it may be preferable to have a distributor nose of the push - member oriented in the same direction as the wider side of the container in the blocked position , which results in the smallest overall size , and in a direction perpendicular to this direction in the position of use for an improved projection of the nose relative to the side of the container , which is permitted by the ring having two ramps .