Pivoting link subassembly

A pivoting link subassembly of a linkage support system includes a first link having a circular bore hole therein, a second link having a non-circular bore hole therein, a washer positioned between the links so as to be aligned with an axis extending through the aligned bore holes, and a rivet which extends through the bore holes to maintain the links together and provide a pivot, the rivet including a shank portion which fills the non-circular bore hole in the second link to assure rotational connection thereto.

FIELD OF THE INVENTION 
The present invention relates to linkage support systems, and more 
particularly to the pivoting link subassemblies which are found in 
virtually all linkage support systems. 
THE PRIOR ART 
Linkage support systems are utilized in many different mechanical devices 
and are commonly employed as movable supports in reclining chairs (see, 
for example, U.S. Pat. No. 4,895,411), for extending and retracting 
convertible tops of automobiles, for extensible lamps, etc. Such linkage 
support systems contain pivoting link subassemblies composed of two links 
and a rivet connecting them together, the rivet acting as a pivot such 
that at least one of the links can be rotated or pivoted relative to the 
other. Often times the two links have holes therein at their opposite ends 
for connection to other links or frame elements of the linkage support 
system, while the rivet extends through aligned rivet holes located 
inwardly of their ends. 
Conventionally used rivets have a head, a first shank portion of larger 
diameter and a second shank portion of smaller diameter, whereas the two 
links have circular rivet holes therein having diameters which are 
slightly larger than the diameters of the corresponding rivet shank 
portions which extend therethrough. During assembly the rivet is passed 
through the respective rivet holes in the links and the second shank 
portion of the rivet which extends beyond the link which is remote from 
the head of the rivet (hereinafter called the remote link) is treated so 
that it will expand to fill the rivet hole in the remote link and also 
form a flange or locking tail portion, thereby pivotally connecting the 
links together. 
However, if the treatment of the second shank portion of the rivet is not 
properly conducted, or as a result of extensive use (relative pivoting of 
the links), the second shank portion of the rivet is or becomes loose 
within the rivet hole in the remote link (such that it will not rotate 
with the remote link), it may become tilted relative to the rivet hole 
axis, causing a binding of the links when rotation is attempted. Over 
time, complete failure of the pivoting link subassembly, and thus the 
entire linkage support system, can occur, resulting in the need for an 
inconvenient and expensive replacement of parts. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a pivoting link 
subassembly for use in a linkage support system which includes two links 
and a rivet which pivotally connects the links together and wherein the 
rivet can be permanently connected to the link remote from the head of the 
rivet, such that failure of the subassembly (and the linkage support 
system of which it is a part) due to loosening of the rivet within the 
remote link can be avoided. 
According to the invention, the link remote from the head of the rivet is 
provided with a non-circular bore hole, such that when the pivoting link 
subassembly is constructed and the shank portion of the rivet near its tip 
is caused to fill the non-circular bore hole, this shank portion of the 
rivet will also have a non-circular cross section. In this way, the rivet 
and the remote link will never rotate relative to one another to cause 
wear on the rivet and ultimate non-alignment of the rivet in the rivet 
hole of the remote link. 
A further understanding of the invention will be achieved by reference to 
the accompanying drawings, taken in conjunction with the following 
discussion.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
As indicated in FIGS. 1-5, the inventive pivoting link subassembly includes 
first and second links 10 and 15, a washer 20 and a rivet 30. As best seen 
in FIG. 4, the first link 10 has a circular bore hole 11 therethrough and 
the second link 15 has a square bore hole 16 therethrough. The rivet 30 
includes a head 31, a first cylindrical shank port 32 having a diameter 
and length so as to extend through and beyond the bore hole 11 in the 
first link, and a second cylindrical shank portion 33 having a diameter 
and length so as to extend through and beyond the bore hole 16 in the 
second link. The diameter of the second cylindrical shank portion 33 is 
less than that of the first shank portion 32. The washer 20, which has an 
inner diameter that is larger than the diameter of the first cylindrical 
shank portion 32, is positioned between the first and second links so as 
to be aligned with an axis A that extends through the aligned bore holes 
11 and 16 and so that the first cylindrical shank portion of the rivet 30 
can extend at least partially therethrough when the elements are connected 
together. The washer 20 is preferably made of plastic. 
When constructing the inventive pivoting link subassembly, the rivet 30 can 
be extended through the bore hole 11, the washer 20 and the bore hole 16, 
and the tip of the second cylindrical shank portion of the rivet is 
subjected to cold heading such that the second shank portion 33 will flow 
out of a cylindrical shape and fill in the open areas of the square bore 
hole 16 and thereafter provide a locking tail 34. The locking tail 34, 
together with head 31, will permanently connect the links together, while 
the washer 20 and the length of the first cylindrical shank portion 32 
will enable one of the links to rotate relative to the other (if 
stationary), or both links to rotate relative to each other, about axis A. 
Due to the reshaping of the second cylindrical shank portion so as to 
completely fill the square bore hole 16, i.e., so as to have a square 
cross section, the rivet 30 will be lockingly and permanently attached to 
the second link 15 and will always rotate in unison therewith. Failure of 
the rivet connection due to relative rotation of the smaller (second) 
shank portion of the rivet and the remote link will be thereby avoided. 
Although a preferred embodiment of the invention has been shown and 
described, changes therein can be made and still fall within the scope of 
the appended claims. For example, the bore hole in the (second) link 
remote from the head of the rivet need not be square in cross section but 
can be any non-circular cross-section, such as rectangular, oval or 
triangular.