with particular reference to the above figures , the reference numeral 1 generally indicates a modular operative block of the dentistry apparatus according to the invention . the operative block 1 has a coupling 2 for an instrument which is connected to one end of a flexible cable 3 ; according to the requirements , the cable 3 internally bears appropriate electric conductors and / or pneumatic and hydraulic ducts for the power supply of said instrument . the cable 3 is supported by a fork - shaped articulated and balanced arm 4 which is articulated above a box - like body 5 . the box - like body 5 has an open front face which is intended to be associated with the rear face of a similar operative block , as described in greater detail hereinafter . a multiple - socket electric connector 6 and a distribution body 7 are accommodated in the box - like body 5 ; said distribution body is traversed at least by the channels 8 and 9 , respectively for the hydraulic and pneumatic power supply , which are cutoff by appropriate electric valve elements 10 . the electric connector 6 is connectable to an electric connector which is complementary thereto and is mounted on the rear face of the operative block which is associated in a modular manner , which is not visible in the drawings . in turn , the power supply channels 8 and 9 are intended to sealingly couple to corresponding couplings which protrude from said rear face of the associated operative block . the box - like body 5 has mechanical coupling means constituted by a pair of pins 11 which protrude from the front face of said box - like body in spaced - apart positions . the pins 11 are intended to couple to respective seats which are correspondingly provided on the rear face of the operative blocks and are constituted by tubular stems 12 , as shown in detail in fig2 . conveniently , each pin 11 is provided monolithically with a related tubular stem 12 so as to constitute a male - female coupling element for connecting to adjacent operative blocks . each tubular stem 12 is through - mounted in a support 13 to which it is rigidly associated by screw means 14 . the pin 11 is externally provided with a transverse groove 15 with flared sides . the groove 15 is suitable for being engaged by a ball 16 for the locking of the associated operative blocks . the ball 16 is mounted freely within a cylindrical accommodation seat 17 which is perpendicular to the tubular stem 12 and passes through a hole 18 of said tubular stem . a tooth 18a prevents the escape of the ball 16 from the hole 18 . the cylindrical seat 17 extends along a sleeve 19 which is defined by the support 13 and slidably bears a piston 20 which defines a groove for an annular sealing gasket 21 . the piston 20 has a concave front surface which acts on the ball 16 against the biasing action of a helical spring 22 accommodated in said cylindrical seat 17 . the sleeve 19 is threaded externally and a ring 23 is screwed thereon and is sealed by a gasket 24 . the ring 23 axially defines a perforated stem 25 . respective flexible tubes 26 , 27 are fitted on the stems 25 of the rings 23 of said pair of coupling means and are connected to related bushes 28 mounted in corresponding seats 29 , 30 defined in the body 7 , as shown in fig4 . the bushes 28 externally define a pair of annular ridges 28a delimiting an accommodation groove for a sealing gasket 31 in the related seats 29 , 30 . the seat 29 is defined at the end of a duct 32 which is transverse to the pneumatic power supply channel 9 ; the duct 32 defines an abutment seat 32a for a shutter 33 which is actuated into its closure position by a helical spring 34 . the seat 30 is in turn connected to a branch duct 35 which leads from the branch duct 32 ; the branch duct 35 leads below the distribution body 7 . a further shutter 36 is slidably mounted in the duct 35 and is intended to define a vent valve . the shutter 36 has a conical profile for engaging an annular gasket 37 accommodated at the end of the duct 35 ; the shutter 36 is biased towards a closure position by a helical spring 38 . the gasket 37 is retained by a plate 39 from which a tang 40 of the shutter 36 protrudes and functions as a pushbotton . a further plate 41 retains the bushes 28 in the respective seats 29 , 30 . during installation , the operative blocks which have the chosen instruments are combined in a battery by placing the front of one adjacent to the rear face of the other . the pins 11 of each operative block are therefore inserted in the correspondiing tubular stems 12 of the adjacent operative block . this insertion is allowed by the retraction of the ball 16 into the accommodation seat 17 ; the piston 20 , which is actuated by the spring 22 in the opposite direction with respect to the ball 16 , in fact does not act on said ball . the operative blocks combined in a battery are fixed in a similar manner to a common support which , in a known manner , is supported by an articulated arm and can be connected to the electric , hydraulic and pneumatic power supply . the adjacent arrangement of the operative blocks furthermore determines the coupling of the electric connector 6 to the element which is complementary thereto and the coupling of the power supply channels 8 and 9 to the corresponding couplings which protrude from the rear face of said operative blocks . in this manner , one obtains a pair of continuous ducts which transverse the battery of operative blocks and which are intended to be connected to the hydraulic and pneumatic power supply , and the power supply to said blocks is furthermore thus obtained . in order to perform the mutual locking of the operative blocks it is sufficient to connect the apparatus to the compressed - air delivery . the pressure of the flow of air which passes through the pneumatic power supply channel 9 is such as to open the shutter 33 , against the biasing action of the spring 34 , so as to connect the channel 9 to the ducts 32 and 35 of the distribution body 7 ; said ducts 32 and 35 are in turn connected , by means of the flexible tubes 26 and 27 , to the chambers defined by the accommodation seats 17 of the pistons 20 . the pistons 20 are therefore actuated so as to push the related balls 16 to engage the groove 15 defined on the pins 11 . when the pressure in the pneumatic supply channel ceases , the shutter 33 is pushed so as to instantly close the abutment seat 32a . this forms a pressurized compartment which commprises the ducts 32 and 35 , the flexible tubes 26 and 27 and the chambers defined by the seats 17 ; said compartment has appropriate gaskets so as to ensure the sealing of the compressed air enclosed therein . even at rest , therefore , the pistons 20 are actuated by a pressure which is sufficient to determine the locking of the pins 11 on the part of the respective balls 16 . in order to release the operative blocks it is necessary to press on the tang 40 which protrudes downward from the distribution body 7 so as to open the shutter 36 of the vent valve of the compressed air which locks the balls 16 . the described apparatus allows , in summary , to rapidly mount in a safely stable manner the different modular operative blocks without resorting to screw means and the like . the disassembly of the operative blocks for the addition or removal of an instrument or for performing maintenance is also rendered equally simple . in the practical embodiment of the invention , the materials employed , as well as the shapes and dimensions , may be any according to the requirements .
the modular dentistry apparatus comprises a plurality of modular operative blocks which each bear a respective instrument and have electric connection means and channels for supplying hydraulic and pneumatic power to said instrument which are suitable for being connected to similar connectors and power supply channels . the operative blocks are mutually associable in series by means of coupling means which comprise at least one pin which protrudes from a front face of each operative block and is adapted for coupling to a corresponding seat arranged on a rear face of an adjacent operative block and to be retained by locking means which are pneumatically actuated by means of a duct which is connectable to the pneumatic power supply channel of the instrument .