with reference to the drawings , the quick - coupling device for pipelines and the like in accordance with the invention has been generally identified by reference numeral 1 . it is designed to connect , in a quick and easily separable manner , two pipes 20 or , alternatively , one pipe 20 to a device such as a compressor , a tank or other similar device . the quick coupling 1 comprises a socket 2 having a central axis 2 a and a fitting element 3 to be partly fitted in socket 2 and coupled thereto , preferably being of cylindrical shape . in particular , the fitting element 3 is connected to a pipe 20 , while socket 2 is connected to a tank or the like by threading . the socket 2 and fitting element 3 internally have a first channel 2 d and a second channel 3 b respectively , that are mutually connected for fluid passage , when the socket 2 a and fitting element 3 are fastened to each other . in more detail , the first channel 2 d is adapted to receive the fitting element 3 through an inlet 2 c . the second channel 3 b , on the contrary , comprises an outlet 3 e through which the fluid flows from the fitting element 3 to the socket . the fitting element 3 , shown in fig7 , externally has a coupling surface 3 d that is substantially cylindrical and with an axis substantially coincident with the central axis 2 a , when the fitting element is inserted in the socket 2 . furthermore , this coupling surface 3 d is continuously smooth , i . e . devoid of overhangs or other protruding elements except for a single discontinuity represented by a groove 3 a that is axially symmetric to , and made to a precise distance from the outlet 3 e , as hereinafter better specified . it also has a counter - surface 3 c close to the outlet 3 e and substantially perpendicular to the central axis 2 a . the socket 2 comprises a locking element 4 that can be moved in a radial direction relative to the central axis 2 a and preferably has an almost circular shape , an outer body 5 defining a first portion of channel 2 c and designed to contain , at least partially , the locking element 4 , and an extractor 6 defining a second portion of channel 2 c and adapted to move relative to the outer body 5 in a direction almost parallel to the central axis 2 a . in greater detail , the outer body 5 has an annular cavity 5 a facing cavity 2 c and designed to house , at least partially , the locking element 4 . this annular cavity 5 a extends , as shown in fig3 , in an inclined direction 5 b relative to the central axis 2 a through an angle α in such a manner that the locking element 4 , when it moves in a radial direction towards the central axis 2 a , simultaneously moves in the direction of the central axis 2 a towards the inlet 2 c . in particular , angle α is substantially included between 45 ° and 55 ° and , preferably , angle α is included between 48 ° and 52 °. finally , the outer body 5 has substantially a cylindrical shape and , preferably , with a shaped outer surface so that it can be easily grasped by wrenches or the like . further , it can be advantageously provided with an outer thread adapted to be connected , by screwing , with a tank or the like . the locking element 4 also comprises a plurality of locking sectors 7 , preferably four , that are at least partly housed inside the annular cavity 5 a . the locking sectors 7 are adapted to be mutually and radially moved . furthermore , due to the particular geometry of the annular cavity 5 a , the sectors 7 , during their radial displacement , advantageously move along an inclined direction 5 b , i . e . they simultaneously move in a radial direction and in a direction parallel to the central axis 2 a toward the inlet 2 c . said movement allows two different positions of the locking element 4 to be defined : a release position ( fig1 and 11 ) at which positioning of the locking sectors 7 enables movement of the fitting element 3 relative to the socket 2 ; and a locking position at which the locking sectors mutually and tightly connect said two components . in detail , in the locking position , only a portion of the locking element 4 is inside the cavity 5 a , while in the release position , the locking sectors 7 are spaced apart from each other to a greater extend and almost fully laying inside the cavity 5 a . in conclusion , when moving from the release position to the locking position , there is a reduction in the distance between the locking sectors 7 and a consequent reduction in the diameter of the locking element 4 , respectively . in particular , reduction in the distance between the locking sectors 7 is obtained through a spring 8 externally surrounding the locking element 4 , as shown in fig5 a and 5 b . said spring is disposed within a housing 7 a placed on the outer edge , i . e . the one to a greater distance from the central axis 2 a , of each locking sector 7 . in addition , the spring 8 is taking up almost the whole height of the housing 7 a calculated in a direction parallel to the central axis 2 a , so as to ensure a correct positioning of spring 8 and avoid undesired movements of the same . furthermore , the spring 8 is a metal helical spring preferably made of steel and preferably a spiral spring of which the ends 8 a are rectilinear to avoid them being inserted between two locking sectors 7 , when the locking element is in a release position , inhibiting returning to the locking position . in particular , the ends 8 a are tangent to the circumference defined by spring 8 in a rest position ( fig2 ). finally , each of the locking sectors 7 has a ridge 7 b on its face close to the central axis 2 a , as shown in fig5 a and 5 b , which in the locking position enters the cavity 3 a locking the fitting element 3 and socket 2 with each other . upon movement to the release position , the ridge 7 b comes out of the cavity 3 a enabling mutual motion between the fitting element 3 and the socket 2 . the ridge 7 b has an upper conical wall 7 c advantageously extending in an oblique direction 7 d , being inclined through an angle β relative to the central axis 2 a ( fig5 a ) to allow movement of the locking element 4 from the locking position to the release position , when the fitting element 3 is inserted in socket 2 . in particular , the fitting element 3 , when inserted inside the socket 2 , exerts pressure on the upper conical surface 7 c causing the sectors 7 to enter the annular cavity 5 a and therefore allowing full introduction of the fitting element 3 . in particular , angle β is substantially between 45 ° and 55 ° and , preferably , it is between 48 ° and 52 °. in addition , due to the presence of a lower wall 7 g , extraction of the fitting element 3 is facilitated . in fact , the extractor 6 is designed to press on said upper conical wall 7 c so as to move the locking element 4 from the locking position to the release position , thus clearing the groove 3 a and allowing the fitting element 3 to be pulled out . in addition , the ridge 7 b has a lower surface 7 e almost perpendicular to the central axis 2 a , said surface being adapted to interfere with the counter - surface 3 c of the groove 3 a . due to this geometry , during the extraction of the fitting element 3 , the lower surface 7 e abuts against the counter - surface 3 c preventing the fitting element 3 from being pulled out and aligning it with the axis 2 a . this advantage is also obtained due to the cavity 5 a that , being inclined in the opposite direction relative to the extraction direction of the fitting element 3 , prevents an undesired separation of the quick - coupling device 1 . furthermore , the upper surface of the cavity 5 a promotes the entry of the ridge 7 b into the groove 3 a when tightening occurs . finally , each sector 7 has , below the lower surface 7 e , and preferably also in correspondence of the ridge 7 b , a cylindrical surface 7 f with an axis substantially coincident with the axis 2 a . the extractor 6 is designed to slide relative to the outer body 5 , in a direction almost parallel to the central axis 2 a and is advantageously provided , at the lower base opposite to the abutment disc 6 b , with teeth 6 a ( fig4 ) adapted to be disposed between the locking sectors 7 . in particular , when the locking element 4 moves to a locking position , the locking sectors 7 abut against the teeth 6 a determining a minimum distance between said locking sectors 7 and , therefore , a minimum size of the locking element 4 . finally , the number of teeth 6 a is preferably the same as that of the locking sectors 7 , i . e . four . in addition , the lower base of the extractor 6 and the upper base of the locking element 4 are advantageously inclined with respect to the central axis 2 a and parallel to each other , so that movements of the extractor 6 gives rise to a displacement of the locking sectors 7 and vice versa . in greater detail , lowering of extractor 6 causes an increase in the sizes of the locking element 4 , i . e . passage of same to a release position ( fig1 ), whereas a reduction in the sizes of the locking element 4 , i . e . a return to the locked position , causes a raising of extractor 6 . in addition , the extractor 6 is partly housed within the outer body 5 and has an almost cylindrical shape . at the base external to the outer body 5 it has an abutment disc 6 b ( fig4 ) designed to push against the upper edge of the external body 5 when the extractor 6 is pressed against said outer body 5 . socket 2 , in addition to the above mentioned components , comprises a stop ring 9 adapted to be inserted , once locking between fitting element 3 and socket 2 has been completed , between the abutment disc 6 b and the outer body 5 to prevent movement of extractor 6 relative to said outer body 5 . preferably , the stop ring 9 is an open spring ring , i . e . its circumference is split and more specifically , it is a seger ring or the like . in order to prevent the extractor 6 from coming out of the outer body 5 , the extractor sliding movement is further limited by a retainer 10 shown in fig2 . this retainer 10 is simultaneously housed inside two grooves 10 a formed in the extractor 6 and the outer body 5 and always facing each other , at least partly . the retainer 10 preferably consists of an open spring ring so as to facilitate insertion into the grooves 10 a . in particular , during the assembling step , it is enlarged and easily inserted into the grooves 10 a of extractor 6 . once it has been positioned , it is allowed to expand so as to adhere to the groove 10 a and , finally , extractor 6 is forcibly inserted into the outer body 2 . socket 2 further comprises an o - ring 11 or other similar means designed to ensure the sealing action of the fluid coupling device 1 . the o - ring 11 is advantageously at least partly housed inside a groove 5 c ( fig3 ) conveniently formed in the outer body 5 under cavity 5 a and , in order to avoid dangerous displacements of the o - ring 11 , a sealing component 11 a , a ring for example , can be disposed within the groove 5 c , so as to lock the o - ring 11 inside the groove 5 c . shown in fig8 is a second possible configuration of the ogive - shaped coupling device according to iso standard 8434 - 1 : 2007 , which is designed to bring into fluid connection two pipes 20 or one pipe 20 connected to a device , such as a tank . in this example , the coupling device comprises a fitting element 3 and a socket 102 having a central axis 102 a and including a first channel 102 d designed to house the fitting element 3 . socket 102 , as shown in fig8 , has a locking element 104 to secure the fitting element 3 to the socket 102 by tightening , a base body 105 provided with a cavity 105 a adapted to contain , at least partially , the locking element 104 , and a closing element 106 designed to be secured to the base body 101 , preferably by threading , carrying out said tightening of the locking element 104 . in this preferred embodiment , the closing element 106 is designed to be moved along the central axis 102 a and to be rigidly secured to the base body 105 by a threaded coupling , while the locking element 104 has an almost cylindrical shape characterised by a frustoconical end adapted to be inserted inside the cavity 105 a . in particular , after the fitting element 3 has been inserted into the socket 102 , the closing element 106 , being secured to the base body 105 , presses the locking element 104 within the cavity 105 a , which locking element is therefore forced between the fitting element 3 and socket 102 thus carrying out the tightening of the fitting element 3 to socket 102 . the socket 102 preferably has sizes in accordance with iso standard 8434 - 1 : 2007 or subsequent modifications to said iso standard . the fitting element 3 , shown in fig7 , is the one previously described and the given distance of groove 3 a is greater than the distance between the cavity 105 a and outlet 3 e when the fitting element 3 is secured to the socket 102 , so that it does not interfere with said tightening action . finally , as in the preceding preferred embodiment , groove 3 a has a counter - surface 3 c , i . e . the surface of groove 3 a close to the outlet 3 e , that is preferably substantially perpendicular to the central axis 102 a . operation of the quick - coupling device for pipelines and the like described above as regards structure is the following . once pipes 20 have been connected to socket 2 and to the fitting element 3 , the fitting element 3 is inserted into socket 2 so that said components are secured to each other . the fitting element 3 passes through the extractor 6 and abuts against the ridges 7 b of the locking sectors 7 . then the fitting element 3 starts pressing on said ridges 7 b causing passage from the locking position to the release position of the locking element 4 . in particular , the locking sectors 7 are moved apart from each other , i . e . the locking element increases its diameter and the locking sectors 7 are almost fully housed within the cavity 5 a ( fig1 ) thus enabling the fitting element 3 to complete its fitting . in particular , the fitting element 3 continuing its movement comes into contact with the o - ring 11 deforming it and carrying out a fluid - tight connection . when the fitting element 3 is inserted , the groove 3 a faces the locking sectors 7 that , being pressed by spring 8 , push the ridges 7 b into said groove 3 a securing the fitting element 3 to the socket 2 and bringing the locking element 4 back to its locking position , as shown in fig4 . in addition , due to their displacement , the locking sectors 7 abut the teeth 6 a causing the locking element 4 to have size close to the minimum size , but not strictly coincident with said minimum size . consequently , the locking element 4 axially compresses the fitting element 3 centering it on the axis 2 a , in particular by means of the cylindrical surface 7 f . in addition , before locking , the stop ring 9 is preferably introduced between the abutment disc 6 b and the outer body 5 inhibiting any motion of the extractor 6 , so as to avoid an undesirable disengagement of the quick - coupling device 1 . when the quick - coupling device 1 needs to be disengaged , i . e . the fitting element 3 is needs to be separated from socket 2 , the stop ring 9 is removed from its housing and the extractor is lowered bringing the abutment disc 6 b almost in contact with the outer body 5 . this movement of the extractor 6 causes passage of the locking element 4 from the locking position to the release position , i . e . ridges 7 b of the locking sectors 7 come out of the groove 3 a enabling the fitting element 3 to be pulled out of the socket 2 . once the fitting element 3 has been pulled out , the locking element 4 , due to action of the spring 8 , goes back to the locking position with the locking sectors 7 being adjacent to teeth 6 a , as shown in fig1 . a first advantage of the quick - coupling device 1 is represented by the high reliability and duration . in fact , due to the presence of teeth 6 a , the locking sectors 7 going back to the locking position are not submitted to dangerous mutual displacements and their mutual distance is almost unchanged and therefore the tightening strength between fitting element 3 and socket 2 is not diminished . another advantage is represented by the quick - coupling device ability that is ensured by the particular geometry of the lower surface 7 e and the counter - wall 3 c . the quick - coupling device 1 is therefore able to withstand pressures up to 350 bars . still another advantage is provided by the metal spring 8 adapted to have a longer duration and greater spring force , also ensured by the number and shape of the sectors 7 . a further important advantage is represented by the possibility of using the fitting element 3 also with ogive - shaped coupling devices of the type iso standard 8434 - 1 : 2007 presently known . in fact , the particular height where the groove 3 a is formed , does not prevent the known quick - coupling devices , as above described , to be connected and fastened . the invention is susceptible of variations falling within the inventive idea . all of the details can be replaced by equivalent elements and the materials , shapes and sizes can be of any nature and magnitude .