referring now to the drawings , as shown in fig1 a substantially rectangular floor opening 2 is bored in a floor 1 . the rectangular floor opening 2 includes a plate support 2a formed on its inner peripheral surface for supporting a substantially rectangular base plate 12 thereon . the base plate 12 has a pair of bracket shaped openings 12a near the opposite ends thereof . the basic plate 12 has also a substantially circular opening 12b bored in its center for receiving a pole 11 . four holes 12c are bored near the inner peripheral surface of the circular opening 12b . a plurality of holes 12d are bored adjacent to the outer peripheral surface of the base plate 12 . two taper surfaces 12e are formed on the inner wall of the bracket shaped openings 12a and near the inner peripheral surface of the circular opening 12b . reference numeral 12f denotes the four recesses of the bracket shaped opening 12a . two notches 12g are formed on the inner wall of the circular opening 12b in parallel to the bracket shaped openings 12a and are located diametrically opposed across the center axis of the circular opening 12b . a cylindrical anchor socket 5 is disposed under the rectangular opening 2 for receiving the end of the pole 11 . the anchor socket 5 is firmly fixed in a concrete base 6 . four cylindrical spacers 14b are detachably disposed on four corners of a rectangular holder plate 14 which is firmly fixed on the upper surface of the anchor socket 5 by welding . as clearly seen in fig1 the base plate 12 is secured to the holder plate 14 through the four spacer 14b by means of four screws 13 which are screwed into four threaded portions 14a ( shown in fig6 ) through the four holes 12c and four spacers 14b . as a result , the outer peripheral section of the base plate 12 is firmly supported by the plate support 2a . as shown in fig1 to 5 , reference numeral 15 denotes a substantially rectangular frame 15 which may be mounted on the upper surface of the base plate 12 . the profile of the outer peripheral surface of the rectangular frame 15 essentially matches that of the base plate 12 as best shown in fig6 . the frame 15 has a plurality of hemispherical projection 15a each of which is inserted into the plurality of holes 12d , respectively , for restraining the horizontal movement of the frame 15 relative to the base plate 12 . the frame also includes four l - shaped fasteners 15b projecting near its four corners for engaging with the four recesses 12f so that the tab portions of the l - shaped fasteners tightly engage with the bottom surface of the base plate 12 . moreover , the frame 15 has two pairs of bearing surfaces 15c opposing the two notches 12g of the circular opening 12b , respectively , and further has two pairs of bearing surfaces 15f in the four corners thereof . as best seen in fig2 the frame 15 includes two pairs of hemispherical projections 15d and two pairs of recesses 15e formed behind the projections 15d in such a manner that the projections 15d may be elastically deformed outwardly in the horizontal direction of the frame 15 . although the bottom surface of the frame 15 mates with the upper surface of the base plate 12 , the frame 15 does not cover the pair of bracket shaped opening 12a , the pair of notches 12g and the four recesses 12f . as shown in fig1 reference numeral 16 denotes a lid assembly which is movably retained between the basic plate 12 and the frame 15 by means of two pair of pins 16e and 16i . the lid assembly 16 comprises a pair of lid members 16a and 16b . the respective lid members 16a and 16b are a first member 16c having a semicircular cut - out 16d and a second member 16f serving as a lid for closing the circular opening 12b . as shown in fig6 and 7 , the first and second members are pivotably connected by means of a hinge 16g such that the angle between the first and second members may become an acute angle . each of the adjacent ends of first and second members 16c and 16f is formed with a 45 ° taper surface , as best seen in fig7 and pivot about a hinge pin 16h . as shown in fig8 while the pair of first members 16c are laying horizontally on the base plate 12 , the two pairs of pins 16e engage with the two pairs of bearing surfaces 15c , and also one large circle is formed , by the two semicircular cut - outs 16d of the first members 16c , whose diameter is equal to or larger than that of the inner periphery of the anchor socket 5 . conversely , as shown in fig6 while the pair of second members 16f are laying horizontally on the base plate 12 , the two pairs of pins 16i engage with the two pair of recesses 15f . the base plate 12 , frame 15 , and lid assembly 16 may be made of any of various materials , such as metals , synthetic resins , such as for example , engineering plastics , or so forth . while the frame 15 and the lid assembly 16 are mounted on the base plate 12 such that the four l - shaped fasteners 15b are pushed into the four recesses 12f and the pins of the lid assembly 15 move within the predetermined range defined between the frame 15 and the basic plate 12 , if the level of the upper surfaces are different from that of the floor 1 , the level can be easily adjusted by the spacers 14b after removing the four male screws . as will appreciated from the above , although the floor fixture of the preferred embodiment according to the present invention is described as including a circular opening for the cylindrical pole , it is not intended to limit the invention of floor fixture thereto . for instance , the floor fixture of the invention comprises a rectangular opening for a rectangular pole . the movement of the lid assembly 16 of the preferred embodiment of the invention will be more clearly understood from the following detailed description : as shown in fig6 when the pair of second members 16f of the lid assembly 16 are horizontally arranged , the pair of first members 16c hang vertically and the adjacent surfaces of first members 16c abut each other . in this condition , the pair of first members 16c function as weights for preventing the second members 16f from bouncing open when the floor 1 is jarred . further , the two pairs of hemispherical projections 15d of the frame 15 function as fasteners for fastening the ends of the second members 16f . as a result , the lid assembly 16 is effectively kept in the fully closed position . as shown in fig7 while the pole 11 is supported in the floor 1 for sports using a net , such as volley ball , tennis , or so forth , the lid assembly 16 is moved from the fully closed position to the fully open position . this movement of the lid assembly 16 , shown in an intermediate position in phantom lines , is performed as follows : first , the ends of the pair of second members 16f adjacent to the elongated bracket shaped openings 12a are pushed into the bracket shaped openings 12a , and at the same time , the two pairs of pins 16i separate from the two pairs of bearing surfaces 15f . thus , the pair of second members 16f are lowered into the bracket shaped openings as the pair of first members 16c is moved from the vertical position to the horizontal position . in this way , the lid assembly 16 is positioned in the full open position in which the free ends of the pair of first members 16c abut each other and their hemispherical openings form one large circle for receiving the end of the pole as shown in fig8 . in this fully open position of the lid assembly 16 , the two pairs of pins 16e of the first members 16c mate with the two pairs of the bearing surfaces 15c and in this condition , the pair of second members 16f function as weights for preventing the first members 16c from bouncing up when the floor 1 is jarred . furthermore , the two pairs of semicircular projections 15d of the frame 15 function to engage the sides of the first members 16c so as to restrain them . next , when the lid assembly 16 is moved from the full open position as shown in fig8 to the full closed position as shown in fig6 the abutting ends of the first members 16c are pushed downward . after this , the movement of the lid assembly 16 is the reverse of that set forth above . although the preferred embodiment of the invention has been disclosed in terms of a floor fixture used for supporting poles for athletic sports , such as tennis , volley ball , within gymnasiums , it is not intended to limit the scope of the invention to such floor fixture . for instance , the structure of the floor fixture may be applicable as a door to a bin for storing foods under the floor of a kitchen . the invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof . therefore , the invention should be understood in all respects as defined by the appended claims rather than by the foregoing description and all modifications which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein .
a fixture for supporting a pole in a gymnasium floor comprises a frame on which a pair of hinged lid members are supported . the hinged lid members are each formed with a flat rectangular piece and a piece comprising a semicircular recess and are slidable along tracks so that while the upper surface of the semicircular recessed pieces are flush with the floor the rectangular pieces hang vertically beneath the floor and while the rectangular pieces are flush with the floor the semicircular recessed pieces hang vertically beneath the floor . the semicircular pieces cooperate to define an opening through which the pole can be received and the rectangular pieces cooperative to cover the opening . with this arrangement , no part of the fitting protrudes from the floor so as to pose a hazard .