Chair

Chair including a base structure, a seating structure having a seat of predetermined depth and a connecting structure for connecting the base structure and the seating structure. The base structure and the seating structure each include two coupling parts which extend along corresponding extension axes, and the connecting structure includes two connecting nuclei at the sides of the two structures, having a limited depth with respect to the depth of the seat. Each connecting nucleus includes two coupling counter slots which may interlock with the two coupling parts of the base structure and with the two coupling parts of the seating structure, respectively, along the extension axes of the above-mentioned coupling parts.

BACKGROUND OF THE INVENTION 
This invention refers to a chair comprising: 
a base structure 
a seating structure with a seat of a predetermined depth, 
means for connecting the two structures 
DESCRIPTION OF THE PRIOR ART 
This type of chair is known from European patent application n. 0 131 553, 
in which the base structure includes two pairs of tubular legs, in the 
shape of an upside-down "V" and attached at the top to two reinforcement 
supports connected by a cross-piece. The seating structure includes a seat 
and a backrest, supported by two levers and two side arms, respectively. 
The connection means include fulcrum joints and springs connecting the 
levers and arms to the supports and to each other. This chair is rather 
complicated and therefore costly due to the number and structure of the 
joints, which require a high degree of workmanship and difficult assembly. 
SUMMARY OF THE INVENTION 
The technical problem of the present invention is to build a chair that is 
simple, in which the connections between the base structure and the 
seating structure allow different types of chairs to be manufactured with 
rapid assembly, which is highly reliable and low in cost. 
This problem is solved by the chair in this invention, which is 
characterized by the fact that the base structure and the seating 
structure each include two coupling parts which extend along corresponding 
extension axes, and the connection means include two connection nuclei 
arranged on the sides of the two structures and having limited depth with 
respect to the seat depth, and in which each connection nucleus includes 
two interlocking counter slots for coupling with the two coupling parts of 
the base structure and the two coupling parts of the seating structure, 
respectively, along the extension axes of the two coupling parts.

DETAILED DESCRIPTION OF THE INVENTION 
Chair With Fixed Seat 
With reference to FIGS. 1, 2, 3 and 4, a chair is generically indicated by 
the number 11 and includes a base structure 12, a seating structure 13 
with a seat 14 and means 16 to connect the two structures 12 and 13, 
symmetrical with respect to a vertical geometric symmetry plane 15. To 
make the description clearer and avoid misunderstandings in 
interpretation, the term forward or front or depth refers to the direction 
indicated by the arrow 17, the term back or rear refers to the opposite 
direction, the term side or horizontal refers to a direction perpendicular 
to the vertical symmetry plane 15 of the chair 11. 
The base structure 12 and the seating structure 13 each include two 
coupling parts 18 and 19, 21 and 22 which in the preferred form of 
execution protrude and extend along corresponding base coupling axes 23 
and seating coupling axes 24. The means of connection 16 include two 
connection nuclei 26 and 27, approximately parallelepipedal in shape and 
placed at the sides of the two structures 12 and 13. The seat 14 has a 
depth according to the usual standards of approximately 50 cm., and each 
nucleus has a corresponding depth of approximately 9 cm., a height of 
approximately 10 cm., and a horizontal measurement of approximately 5 cm., 
limited with respect to the depth of the seat 14. Satisfactory results can 
also be achieved with a nucleus depth contained within the ratio of 
0.15-0.25 with respect to the depth of the seat. The two nuclei 26 and 27 
are substantially identical and interchangeable, and thus to simplify the 
description the details given refer to a single nucleus. 
Each nucleus 26, 27 includes two coupling counter slots 28 and 29, 
interlocking respectively with the two coupling parts 18 and 19 of the 
base structure 12 and with the coupling parts 21 and 22 of the seating 
structure 13 along the axes 23 and 24 of the above coupling parts 18 and 
19, 21 and 22. Each connecting nucleus 26, 27 consists of a single piece 
of metal, mainly a press-molded aluminum alloy, having a lower surface 31 
in which the two coupling counter-parts 18 and 19 of the base structure 12 
are fit and an upper surface 32 in which the two coupling counter-parts 21 
and 22 of the seating structure 13 are made. The lower surface 31 and the 
upper surface 32 are parallel. In the form of execution in which the 
coupling parts protrude, the two coupling counter slots 28 and 29 
associated with the lower surface 31 and the upper 32 receive coupling 
parts 18 and 19, 21 and 22. 
The base structure 12 includes a cross-piece 33 with the coupling parts 18 
and 19 at either end. These parts each include two pins which, in use, 
extend upward to fit into the two cylindrical slots 28 of the lower 
surface 31. The cross-piece 33 consists, for example, of two hollow 
longitudinal profiles 34 and two horizontal hollow profiles 36, attached 
in a known manner, for example through welding. 
The seating structure 13 includes, at the sides of the seat 14, the two 
coupling parts 21 and 22, which each include a fixed intermediate piece 
35, 40 in a ".pi." shape, fitted with two pins which, in use, extend 
downward to fit into the two cylindrical slots 29 of the upper surface 32. 
The axes 23 and 24 are parallel in use, and basically vertical. The seat 
14 consists of a seat with two tubular side borders 37 and 38. Each pair 
of pins 21, 22 of pieces 35, 40 is attached to a tab 39, 41 with a concave 
upper part, complementary to the section of borders 37 and 38 and attached 
at the bottom to the borders 37 and 38 of the seat 14 by means of screws 
42. Known attachment means, for example screws 43, are used to lock the 
pins 18 and 19 of the base structure 12 in the lower slots 28 of the 
nuclei 26 and 27, and the pins 21 and 22 of the seating structure 13 in 
the upper slots 29 of the nuclei 26 and 27. 
The base structure 12 includes two pairs of tubular legs 44 and 46, 
attached to the lower parts of pins 18 and 19, respectively. The pairs of 
legs 44 and 46 can be made from four separate profiles, as represented in 
FIG. 1, or can be made from only two profiles in such a way as to be 
connected via a section 47 as shown in FIG. 6. Alternatively, the 
cross-piece 33 can be attached to a rotating pedestal 44 with respect to a 
base 50, in turn rolling on casters 49 as shown in FIG. 5. The legs 44 and 
46 and the pedestal 44 in FIGS. 1, 5 and 6 are shown merely as examples, 
but do not limit from any other possible solutions. 
The seating structure 13 (FIGS. 1, 2, 3 and 4) includes a backrest 51 edged 
by a tubular border 52 from which two side pins 53 and 54 protrude, 
jointed with return springs to allow the backrest to be inclined. These 
pins fit into the corresponding cylindrical slots 56 and 57 on two side 
support arms 58 and 59. Each support arm 58 and 59 is profiled at a nearly 
right angle, and has a protruding cylindrical pin 61, 62 on the front 
which fits into the side border 37, 38 of the seat 14, and may be attached 
to it by means of the screws 42. 
The two connecting nuclei 26 and 27 each include a vertical groove 63, 
parallel to the cylindrical slots 28 and 29, for the purpose of holding a 
closing element 64 as shown in FIGS. 1 and 2, or alternatively a support 
and clasping element 66, 67 (FIG. 10) as described below. Each nucleus 26, 
27 (FIGS. 1, 2, 3 and 4) also includes two side grooves 68 and 69, 
parallel to each other and perpendicular to the cylindrical slots 28 and 
29, which have the purpose of housing the ends 71 and 72 of the 
cross-piece 33. 
The chair is assembled as follows: 
Each connecting nucleus 26, 27 with slots 28 is positioned along the axes 
23 aligned with the pins 18, 19, and is lowered so that the pins 18, 19 
fit into the slots 28. By pressing lightly towards the base structure 12, 
the nucleus 26, 27 is lowered until the ends 71, 72 are housed and strike 
against the back of the side grooves 68 and 69. The pins 18 and 19 are 
then completely fitted into the slots 28, and the lower surface 31 is in 
contact with the upper end of the legs 44, 46. 
The seating structure 13 is assembled by connecting the backrest 51 to the 
side arms 58 and 59, inserting the pins 53 and 54 into the slots 56 and 
57, and fastening the unit in place using screws or holding pegs not shown 
in the drawings. Next the pins 61 and 62 of the side arms 58 and 59 are 
fitted into the side borders 37 and 38 of the seat 14, and the 
intermediate parts 35, 40 are attached to the borders 37, 38, positioning 
the tabs 39 and 41 against the lower surfaces of the side borders 37 and 
38, and holding the seat 14, the side arms 58 and 59 and the tabs 39 and 
41 in place by means of the screws 42. The pins 21 and 22 are thus firmly 
attached to the seat 14. 
The seating structure 13 is then positioned with the pins 21 and 22 aligned 
with the slots 29 in the upper surfaces 32 of the nuclei 26 and 27. The 
pins 21 and 22 are fitted into the slots 29 and lightly pressed towards 
the base structure 12 to lower the seating structure 13 until the lower 
surfaces of the tabs 39 and 41 stop against the upper surfaces 32 of the 
nuclei 26 and 27. The screws 43 are inserted into the through-holes 73 of 
the ends 71 and 72 of the cross-piece 33 until firmly inserted, and pins 
21 and 22 are screwed into the threaded slots 74. Next the closing element 
64 is positioned in the groove 63. 
The chair is thus fully assembled. 
This chair 11 has its seating structure 13 firmly attached to the base 
structure 12. 
Chair With Rocking Seat 
Now we shall describe a variation of the chair indicated by 11', in which 
the seating structure 13 can rock with respect to the base structure 12. 
This is achieved by changing a minimal number of parts with respect to 
those of the chair 11, thus most parts are common to both chairs 11 and 
11'. The same numerical references are therefore used, and the operation 
described above is recalled. In addition, for this chair 11' the legs can 
be of a different type as described above in reference to FIGS. 1, 5 and 
6. 
The chair 11' (FIGS. 2, 6, 7, 8, 9 and 10) includes the base structure 12, 
the seating structure 13 and the connecting means 16 including the 
connecting nuclei 26 and 27 already described in reference to the chair 
11. The base structure 12 includes the cross-piece 33 with the coupling 
pins 18 and 19 at the ends 71 and 72, for the purpose of fitting into the 
cylindrical slots 28 of the lower surfaces 31 of the nuclei 26 and 27 
along the vertical base coupling axes 23. 
The seating structure 13 of the chair 11' also includes the seat 14 and the 
backrest 51 connected to the side arms 58 and 59 fitted into the side 
borders 37 and 38 of the chair 14. In the chair 11', the connection 
between the seating structure 13 and the nuclei 26 and 27 is instead made 
using two "T"-shaped intermediate rocking pieces, indicated as 81 and 82, 
by means of a coupling which rotates along the respective horizontal seat 
coupling axes 90, aligned and perpendicular to the plane of symmetry, 
which allows the seating structure, 13 a limited freedom of oscillation. 
Each piece 81 and 82 includes a central drum 83, 84 and a flange 86, 87 
which protrudes on one side and has a concave upper portion, for the 
purpose of being attached against the lower surface of the tubular side 
borders 37 and 38 of the seat 14 by means of the screws 42. The drum 83, 
84 has a sleeve 88, 89 protruding on the same side as the flange 86, 87 
and with a cylindrical slot 91, 92. Each connecting nucleus 26, 27 has a 
side surface in which a slot 93 is made to house the sleeve 88, 89, and a 
pin 94 which may be coupled to the cylindrical slot 91, 92. The slot 93 is 
positioned in the center of the nucleus 26, 27 between the two side 
grooves 68 and 69. 
Each pin 94 has a threaded internal slot 96 in which a screw 97 is inserted 
to fasten and prevent the sleeve 88, 89 from sliding out of the slot 93. 
To prevent gripping between the cylindrical slot 91, 92 of the sleeve 88, 
89 and the pin 94 during assembly, as described below, a bushing 98 of 
grip-proof material is inserted on the pin 94. 
Flexible means consisting of four springs 99, positioned in the two slots 
29 of the nucleus 26 and in the two slots 29 of the nucleus 27 act on the 
lower surfaces of the flanges 86 and 87 by means of four small pistons 
101. Each spring 99 is pre-loaded to allow the seating structure 13 to 
rock slightly from the normal position, represented by a solid line in 
FIG. 6, to the two extreme rocking positions shown: one represented by a 
dot and line and the other represented by two dots and a line. 
Each connecting nucleus 26, 27 has a housing 102 above the slot 93 and 
positioned between the two vertical slots 29 of the upper surface 32, with 
a hole 103 for the purpose of allowing the passage of a screw 104 to 
attach the elements 64, 66 and 67. 
The closing element 64 has only an aesthetic function, to close the groove 
63, and thus since it need not work together with the other parts it may 
also not be attached, while the support and clasping elements 66 and 67 
must work together with the other parts as described below, and therefore 
are appropriately fastened in place by the screws 104 after being inserted 
in the grooves 63. 
The chair 11' is assembled as follows. 
A support and clasping element 66 is inserted in the grooves 63 of each 
nucleus 26, 27 to achieve performance as shown in FIG. 17, or a support 
and clasping element 66 is inserted in the groove 63 of the first nucleus 
26 and a support and clasping element 67 in the groove 63 of the second 
nucleus 27 to achieve performance as shown in FIG. 10. Both types of 
performance are described in detail below. The support and clasping 
elements 66, 67 are attached in place by means of the screws 104, and then 
the bushing 98 (FIGS. 2, 6, 7, 8, 9 and 10) is mounted on the pin 94 of 
each nucleus 26, 27. 
The springs 99 are mounted on each nucleus 26, 27 with the small pistons 
101 in the slots 29 of the upper surface 32, and a special tool is used to 
pre-load the springs 99. 
Each rocking piece 81, 82 is assembled, positioning the sleeve 88, 89 
aligned with the slot 93, and then the cylindrical slot 91, 92 slides onto 
the bushing 98. The equipment which causes the small pistons 101 to be 
pushed by the springs 99 against the lower surface of the flange 86, 87 is 
then removed. Finally, the screw 97 is screwed into the threaded slot 96, 
thus the piece 81, 82 can rotate around the axis 90 but cannot separate 
from its pin 94. 
The backrest 51 is connected to the side arms 58 and 59 and then to the 
side borders 37 and 38 of the seat 14 as described for the chair 11. The 
seating structure 13 is positioned with the lower surfaces of the side 
borders 37 and 38 over the flanges 86 and 87, and the entire unit is 
fastened with the screws 42. The seating structure 13 is thus connected to 
the two connecting nuclei 26 and 27. 
The seating structure 13 is positioned with the nuclei 26 and 27 in such a 
way that the slots 28 of the lower surfaces 31 are aligned with the pins 
18 and 19, and it is lowered so that the pins 18 and 19 fit into the slots 
28. Pressing slightly towards the base structure 12, the seating structure 
13 is lowered further until the ends 71 and 72 are housed and strike 
against the bottom of the side grooves 68 and 69, and the pins 18 and 19 
are fully housed in the slots 28. As with the chair 11, the screws 43 are 
inserted in the through holes 73 of the ends 71 and 72 of the cross-piece 
until fitted in, and screwed into the threaded slots 106. The chair 11' is 
now fully assembled. 
Variations 
The chair 11 in FIG. 1 and the chair 11' in FIG. 6 can be used for 
collective areas for multi-purpose uses, in which several chairs are 
connected in rows through a clasping system indicated as 111 (FIGS. 1, 2, 
6, 10 and 17). It should be mentioned that the base structure 12 may have 
the legs 44 and 46 in FIG. 1 or those in FIG. 6. 
The clasping system 111 includes the support and clasping element 66 fitted 
into the groove 63 of the nucleus 26 of the first chair, with a 
complementary part 112 and the support and clasping element 67, fitted 
into the groove 63 of the nucleus 27 of a second chair adjacent to the 
first chair, with a complementary part 113. An armrest 114 with a clasping 
element 116 works together with the complementary part 112 and the 
complementary part 113 to keep the first chair permanently attached to the 
second chair. 
The support and clasping element 66 consists of a single metal part, nearly 
prismatic, with the complementary part 112 consisting of a hollow sleeve, 
which protrudes at the side and is positioned in the upper part of the 
element 66. The support and clasping element 67 consists of a single metal 
piece, nearly prismatic, with the complementary part 113 consisting of a 
hollow sleeve, which protrudes at the side and is positioned in the lower 
part of the element 67. Moving the first chair next to the second chair, 
the two sleeves 112 and 113 are vertically concentric and allow the 
clasping element 116 to be inserted in order to fasten the two chairs 
together. 
The clasping element 116 includes a hollow cylinder 117 in which a small 
piston 118 slides. The cylinder 117 has a fork 119 at one end, connected 
to a fin 122 of the armrest 114 by means of a pin 121, and at the other 
end a hole 123 for the passage of the piston 118. The cylinder 117 has a 
cross-hole 124 for the passage of a positioning pin 126. 
The positioning pin 126 is guided in a hole 131 of the support and clasping 
element 66, and a spring 132 keeps it pushed against the small piston 118. 
The rounded end of the positioning pin 126 never touches the back of the 
grooves 127 and 128 because it would be difficult to remove in this case. 
The armrest 114 can be moved from a vertical position, shown in FIG. 10 by 
a solid line, to an inclined positioned determined and defined by the 
bevel 133 on the fork 119, shown by a dot and line, in order to allow the 
chair 11 or 11' to be stacked on top of one another as shown in FIG. 18. 
The clasping system 111 works as follows. 
As described above, the support and clasping element 66 is attached on the 
nucleus 26, and the support and clasping element 67 is attached on the 
nucleus 27. The clasping system 111, which is fastened to the armrest 114, 
is positioned aligned with the hollow slot of the sleeve 112. The armrest 
114 is pushed downward lightly, sliding the clasping device 111 down until 
it is positioned in its working position, in which the lower end of the 
piston 118 protrudes from the sleeve 113. The two chairs 11 or 11' are 
thus permanently attached to each other. 
In order to position the armrest 114 in the inclined position, one proceeds 
as follows. 
The piston 118 is pushed upward against the action of the springs 129 and 
132, and the positioning pin 126 slips out of the groove 127. The armrest 
114 is raised while the positioning pin 126 moves out of the horizontal 
hole 124, and due to the action of its spring 132 it rests on the outer 
surface of the small cylinder 117, until it fits into a second horizontal 
hole 134, to rest with its end fitted into the radial groove 128. The 
armrest 114 may now rotate around the pin 121 until it settles against the 
bevel 133. Even when the armrest 114 is in the inclined position, the 
clasping element 116 remains fitted into the slot of the sleeve 113. 
In order to return the armrest 114 into its original position, one follows 
the above operations in reverse order: thus the armrest 114 is rotated to 
a vertical position and pressed downward. The positioning pin 126 slips 
out of the groove 128 and the horizontal hole 134 until it returns into 
the horizontal hole 124 and the groove 127. 
If one wishes to remove the clasping device 111, one proceeds as described 
above to position the armrest 114 in the inclined position, then a 
screwdriver or similar tool may be used to push on the lower part of the 
piston 118, to move the positioning pin 126 out of the groove 128 and the 
horizontal hole 134. The armrest 114 is now free to be lifted, and thus 
the clasping system 111 is not fitted into the sleeves 113 and 112, and 
the two chairs 11 or 11' are separate from one another. 
In a variation, a chair 11", similar to the chairs 11 and 11' but without 
the legs 44 and 46, may be attached to a bar 136 (FIGS. 13 and 14) for use 
in collective areas, in particular waiting rooms, cafeterias, classrooms 
and meeting rooms. The bar 136 is a normal square bar mounted on mobile 
bases, known on their own merit and indicated generically by the number 
137, to be attached either to the floor (FIG. 16), even with variable 
inclination (FIGS. 14 and 15), or on terraced floorings (FIG. 13). 
Even in this variation, the chair 11" (FIGS. 1, 2, 3, 6, 11, 13 and 14) is 
substantially identical to the chairs 11 and 11' described above, with the 
exception of the base structure 138, which includes two U-forks 139 for 
each chair 11". Each U-fork 139 includes a square slot 141 to be coupled 
with the outer surface of the bar 136, two cylindrical pins 142, similar 
to the pins 18 and 19, to fit into the cylindrical slots 28 of the lower 
surface 31 of each nucleus 26, 27 along the basic coupling axes 23. The 
fork 139 also has two appendices 143, each consisting of a square profile, 
which replace the ends 71 and 72 of the cross-pieces to fit into the side 
grooves 68 and 69 of the nuclei 26 and 27, each having a through hole 144 
for the screws 43. 
The assembly of the chair 11" on the bar 136 is essentially the same as 
described above for the chairs 11 and 11'. The seating structure 13 is 
attached to the tabs 39 and 41, fastened to the pins 21 and 22, using the 
screws 42, and then to the nuclei 26 and 27, which are then rested on the 
bar 139. The U-forks 136 are mounted with the slots 141, which fit onto 
the bottom portion of the bar 136; the pins 142 fit into the slots 28, the 
appendices 143 are housed in the side grooves 68 and 69 of the nuclei 26 
and 27. Next the screws 43 are screwed on to hold the seating structure 
13, the nuclei 26 and 27 and the appendices 143 of the U-fork 139 fastened 
to the bar 136. 
Chair With Tip-Up Seat 
In another variation, a chair 11''' (FIGS. 1, 2, 6, 10, 11, 12, 13, 14, 15 
and 16), similar to the chairs 11, 11' and 11" described above, is mounted 
on the bar 136 for collective areas, in particular for classrooms, 
conference rooms, convention halls and amphitheatres. The bar 136 is 
mounted on the mobile bases 137 to be attached to the floor, even at 
variable inclinations, or on terraced floors like the chair 11". 
The chair 11''' includes the seating structure 13 with the backrest 51 
described above, attached to the side arms 58 and 59, and a tip-up seat 
14' with tubular side borders 151. The seating structure 13 is connected 
to the nuclei 26 and 27 by two fixed intermediate pieces 146, 147 and two 
tipping intermediate pieces 148, 149. The pieces 146, 147 are 
".pi."-shaped like parts 35 and 40, and include the sleeves 152 and 153 at 
the top, respectively. The arms 58 and 59 have the pins 61 and 62 adjacent 
to the borders 151, fitted into the two sleeves 152 and 153. Each sleeve 
152, 153 is attached to the pins 154 and 156, similar to the pins 21 and 
22, which are fitted into the slots 29 on the upper surfaces 32 of the 
nuclei 26 and 27 along the seat coupling axes 24. Screws, similar to the 
screws 42 and not shown in the drawings, hold the pins 61 and 62 of the 
arms 58 and 59 in each sleeve 152, 153. 
The tipping parts 148 and 149 are T-shaped like the parts 81 and 82, and 
include a concave flange 157 and 158 at the top, a central drum 162, 163 
and a sleeve 164, 166 opposite the flange 157, 158. 
The tip-up seat 14' is attached by means of the two side borders 151 on the 
two flanges 157 and 158 of the parts 148, 149 by means of the screws 42. 
Each sleeve 164, 166 has a cylindrical slot 167, 168 and is housed in the 
slot 93 of the nucleus 26, 27 with a coupling that rotates along the 
horizontal seat coupling axes 90, and each cylindrical slot 167, 168 fits 
onto the pin 94 of the nucleus 26, 27. As these parts are metal, the 
bushing 98 of grip-proof material is placed on the pin 94 to prevent 
gripping between the slot 167, 168 and the pin 94. 
Flexible means consisting of two spiral springs 169 and 171, each applied 
between the sleeve 164, 166 and a groove 172 of the nucleus 26, 27 
normally keep the tip-up seat 14' in the tipped position. The sleeve 164, 
166 includes three slots 173 in different angular positions to house one 
end of the spring 169, 171 so as to increase or decrease the tension of 
the spring 169, 171. Each sleeve 152, 153 has a shoulder 174 positioned 
during use on the inner side of the chair 11''' to work with the seat 14' 
and keep it in the seating position. The shoulder 174 has a hole 176 to 
house a pad 177 of plastic for rubber to soften the contact between the 
flange 157, 158 and the shoulder 174. In addition, each sleeve 152, 153 is 
closed at the front by a cap 178, which bears a number so that the chairs 
11''' can be numbered progressively. 
The assembly of the chair 11''' on the bar 136 is essentially the same as 
described above for the chairs 11, 11', and 11". The seat 14' is attached 
to the two flanges 157 and 158 of the T-levers 148 and 149 by means of the 
screws 42. The bushing 98 is mounted on the pin 94, the sleeve 164, 166 is 
positioned in the slot 93 of the nuclei 26 and 27, taking care to position 
the springs 169 and 171 with their ends in one of the slots 173 and the 
other end in the grooves 172 of the nuclei 26 and 27. Using the screws 97, 
the intermediate pieces 148 and 149 are attached axially to the nuclei 26 
and 27 so that they may rotate without slipping out of the slots 93 and 
off the pins 94. 
The backrest 51 is mounted on the arms 58 and 59, and the pins 61 and 62 
are positioned in the sleeves 152 and 153, attaching them with the screws 
42. The pins 154 and 156 are housed in the slots 29 of the upper surfaces 
32 of the nuclei 26 and 27, and then the two nuclei 26 and 27 are 
positioned on the bar 139. The U-forks 136 are mounted with the slots 141 
which fit onto the outer part of the bar 136, the pins 142 rest in the 
slots 28 of the lower surfaces 31, and the appendices 143 in the side 
grooves 68 and 69 of the nuclei 26 and 27. Next the screws 43 are 
positioned, which fit and are screwed into the threaded slots 179 of the 
pins 154 and 156, tightening the bar 139 between the bottom of the forks 
136 and the lower part of the nuclei 26 and 27. The chair 11''' is thus 
mounted on the bar 136. 
The chair 11--11' shown in FIG. 17 may have the seating structure 13 firmly 
attached to the base structure 12, like the chair 11 in FIG. 1, or it may 
have the seating structure 13 rock with respect to the base structure 12, 
like the chair 11' in FIG. 6. In addition, the base structure 12 may have 
legs as shown in FIGS. 1, 5 and 6. 
The chair 11--11' is shown with two arms 114 as an example and not intended 
as a limitation, in order to point out the flexibility of the chairs 
described thus far. Indeed, using the intermediate parts 35, 40; 81, 82; 
146, 147 and 148, 149 and various closing elements 64, 66 and 67, it is 
possible to obtain an infinite series of chairs, such as: chair with fixed 
seating structure without armrests, with a single armrest, with two 
armrests; chair with rocking seating structure without armrests, with a 
single armrest, with two armrests; chair attached in a row, fixed, 
overlapping or tip-up tables, etc. In order to better emphasize the above, 
the chair 11 in FIG. 1 and the chair 11' in FIG. 6 have been shown with 
the closing element 64 described previously. Simply by replacing the 
closing element 64 with the support and clasping element 66, described in 
FIG. 10, and inserting the armrest 114 with the clasping element 111, it 
is possible to achieve the chairs 11 and 11' with a single armrest 114. Or 
by assembling the two support and clasping elements 68 on the two nuclei 
26 and 27 and inserting the two armrests 114 with the clasping elements 
111, the chair 11--11' in FIG. 17 is obtained. 
As described earlier, the two armrests 114 may be moved to an inclined 
position by means of the clasping element 111 of each armrest 114 in order 
to stack the chairs 11 and 11' on top of each other as indicated in FIG. 
18. For this purpose, the nuclei 26 and 27 have two inclined surfaces 182 
on the top to work with the inner portion of the legs 44 and 46 to allow 
and assist the stacking of these chairs. 
Finally, each armrest 114 contains, in the upper part consisting of a 
resting border 183, a slot 184 closed by a removable cap 186, to allow a 
revolving writing table 187 to be inserted and attached; such a table is 
prior art and not described nor shown in detail. 
It is therefore evident that the base structure 12, the seating structure 
13 and the two connecting nuclei 26 and 27 include a series of pins 18, 
19, 21 and 22, a series of slots 28, 93 and 102, and a series of grooves 
63, 68, 69 which work together, and with connecting and fastening parts, 
so as to allow the rapid assembly of a series of chairs with varying 
configurations and performance, using a limited number of pieces and 
parts. 
It is understood that a number of changes and improvements, both in shape 
and in the arrangement of the various parts, may be made to the chairs 11, 
11', 11" and 11''', the base structure 12 and seating structure 13, the 
connecting nuclei 26 and 27, the connecting and clasping systems and the 
assembly sequences described above, without overstepping the limitations 
of the present invention.