Transmission chain

The chain comprises alternately pivotally interconnected outer links and inner links. The outer links are formed by outer plates which are interconnected by spacer members and the inner links are formed by inner plates which are trapped between the outer plates and are rigid with tubular members through which the spacer members extend. Each inner plate comprises two planar portions of rounded or part-circular shape which are interconnected by a center portion. At least a part of the center portion is deformed relative to the general plane of the plate. The inner plates of a given link have their deformed part offset and facing outwardly of the link so as to constitute an entrance or lead-in for sprocket teeth. In this way, the engagement of the chain on the sprocket is facilitated, in particular when changing gear by means of a derailleur acting on the chain.

The present invention relates to transmission chains which may be used 
generally for the transmission of power, in particular for motors and 
vehicles of all types and more particularly for bicycles and, among the 
latter, mainly those comprising a derailleur for changing speed or gear 
and commonly known as multispeed bicycles. 
Known transmission chains are usually formed by alternately outer links and 
inner links. The outer links are formed by two steel plates which are 
suitably cut out and may be treated and are termed outer plates. These two 
plates are interconnected by two cylindrical pins which may be solid or 
hollow and are an interference fit in the two plates and riveted in 
position. The inner links are also formed by two plates which are suitably 
cut out and may be treated and are termed inner plates. These two plates 
of the inner link are interconnected by two hollow spacer members termed 
bushings through which extend the pins of the outer link and thereby 
ensure the connection between the successive links. The bushings are 
fitted into the inner plates. Placed on the bushings between the inner 
plates is a roller which is freely rotatable on the bushing. This roller 
facilitates the engagement of the chain on the chain wheels and sprockets. 
When such a chain is employed in a transmission having a derailleur 
speed-changing system the different speeds are embodied by a succession of 
sprockets which are axially equally spaced apart on a common hub. 
When it is desired to change speed, that is the sprocket on the hub, a 
suitable device, namely a derailleur, is acted upon by the user and this 
derailleur acts on the part of the chain which arrives on the chain 
arrival side of the sprocket so as to bring the chain into the plane of 
each of the successive sprockets. Consequently, the chain is slightly 
distorted and it hooks onto the teeth of the sprocket and mounts on these 
teeth before the rollers of the chain drop into the recesses between these 
teeth for a proper engagement of the chain with the sprocket. 
Research carried out with various modern means of investigation has 
revealed that, in the operation of the derailleur, different phenomena 
occur depending on whether the derailleur is changing up the speeds or 
changing down the speeds. 
Changing up the speeds designates in the ensuing description the operation 
which comprises changing from one sprocket to another larger sprocket and 
changing down the speeds the opposite operation. 
When changing up the speeds, the chain does not pass directly from one 
sprocket to the other but rubs or hooks by the ends of the pins or the 
edges of the plates against the following sprocket. Then, at a given 
moment, the plates are hooked by the teeth and mount on the latter and 
remain there a short moment in equilibrium and then suddenly drop into the 
normal position of engagement of the chain on the sprocket. This procedure 
delays the engagement of the required speed which is not as instantaneous 
as it would be desired. 
When changing down the speeds, similar phenomena occur but, as soon as the 
chain has been bent by the action of the derailleur, it escapes from the 
teeth of a given sprocket and drops onto the sprocket of smaller diameter 
and usually engages the latter very rapidly. 
it is consequently clear that, in order to effect a shifting operation on 
the chain by means of the derailleur, a hooking of the ends of the pins 
should be avoided in order to facilitate the sliding of the plates against 
the side of the sprocket and the passage of the plates on the teeth. Also, 
the chain should have a certain flexibility and a high capacity for very 
rapidly presenting the inner face of the inner plates in alignment with 
the side of the teeth of the sprocket on which the chain is to be engaged, 
since, in any case, when the chain is engaged on the sprocket, it is the 
inner faces of the inner plates which guide the chain on the sprocket and 
not the outer plates which are more specifically provided to transmit the 
pulling or driving forces. 
An object of the present invention is to provide a transmission chain which 
permits speed-changing operations by means of a derailleur which are easy, 
precise and effective within a minimum period of time, owing to a special 
arrangement of the inner plates. 
According to the invention, there is provided a transmission chain 
comprising alternately outer links and inner links which are pivotally 
interconnected, the outer links being formed by outer plates which are 
interconnected by spacer members and the inner links being formed by inner 
plates which are trapped between the outer plates and are rigid with 
tubular members through which said spacer members extend, wherein the 
inner plates each have two planar portions of rounded or part-circular 
shape which are interconnected by a center portion at least a part of 
which is deformed relative to the general plane of the plate, the inner 
plates of a given link having their deformed portion offset and facing 
outwardly of the link so as to constitute an entrance for the teeth of the 
sprockets whereby the engagement of the chain on the teeth is facilitated, 
in particular when the chain is shifted by a derailleur. 
In a preferred embodiment, the center portion of the inner plate has 
lateral edge portions which are deformed and offset from the same side of 
the plate, whereas the median part of the center portion is planar and in 
the same plane as said planar portions. 
According to another embodiment, the center portion is deformed throughout 
the width thereof. 
According to a feature of the invention, the deformed center portion is 
offset in a plane parallel to the general plane of the plate. 
According to another feature of the invention, the deformed center portion 
has in longitudinal section a very wide V-shape having a flat bottom and 
an evolutive profile. 
According to another embodiment, the center portion comprises a planar 
median part offset in a plane parallel to the general plane of the plate 
and two lateral edge portions which are deformed and offset outwardly of 
the link relative to the plane of said median part. 
According to a feature of the invention, the pins of the outer links are 
flush with the outer planar surface of the outer plates of the male links 
or very slightly project therefrom to an extent less than about 1/10 to 
2/10 of a millimeter. 
According to another feature of the invention, the tubular members rigid 
with the inner plates are formeed by two hollow cylindrical spigots 
carried by each plate, the inner plates being freely mounted on the spacer 
members and their lateral displacements being limited, inwardly of the 
link, by rollers of the chain which are mounted on the spigots and, 
outwardly, by the outer plates of the outer links. 
According to another feature of the invention, the outer plates of the 
outer links carry two hollow cylindrical spigots which are asymmetrical 
relative to the longitudinal axis of the chain so as to increase the 
section of the metal in the stressed part thereof. 
According to another feature of the invention, the inner and/or outer 
plates have a profile which is asymmetrical relative to the longitudinal 
axis of the chain and are mounted in reverse relation on the same link so 
as to permit a rapid disengagement of the chain when shifting the chain by 
means of a derailleur.

With reference first to FIGS. 1 and 2, the latter show an inner plate 1 of 
an inner link of a chain. This plate has two planar part-circular end 
portions 2 each of which is provided with an aperture 3 for receiving a 
spacer member or bushing, the part-circular portions being interconnected 
by a center portion having a planar median part 4 in the same plane as the 
part-circular portions 2 and having outer edge portions 5 which are 
deformed laterally outwardly of the same side relative to the plane of the 
planar median part 4. Two plates 1 such as that just described are 
arranged to form an inner link as shown in FIG. 6. the two end portions 2 
of each plate respectively define inner faces which are contained in a 
common plane and confront the inner faces of the other plate. An entrance 
or lead-in 6 are defined by the inner faces of the deformed portions 5 
which inner faces are offset laterally outwardly of the link relative to 
said common plane, this entrance facilitating the engagement of the teeth 
of sprockets on the chain. It will be seen that the inner faces of the 
deformed portions 5 extend from the peripheral edge of the plate 1. The 
plates 1 are interconnected by a spacer member or bushing 7 on which a 
roller 8 is freely rotatable in the known manner. FIG. 13 shows a chain 
formed by such inner links which are interconnected by conventional outer 
links which are formed by outer plates 9 interconnected by solid pins 10 
or hollow pins 10'. 
With reference now to FIGS. 3, 4, 5 and 14, it can be seen how a plate 
1.sup.a having hollow cylindrical spigots may be substituted for the plate 
1 just described to form an inner link of a chain. As before, the plate 
1.sup.a has two part-circular portions 2.sup.a interconnected by the 
planar median portion 4.sup.a which is in the same plane as the 
part-circular portions 2.sup.a and has on its edges a divergent portion 
5.sup.a. The inner faces of the end portions 2.sup.a and the inner face of 
the median portion 4.sup.a are contained in a common plane. However, the 
two part-circular portions 2.sup.a instead of each merely defining an 
aparture comprise a cylindrical spigot 11.sup.a rigid with the planar 
portion 2.sup.a. According to a first embodiment, and when the thickness 
of the plate 1.sup.a is not excessive, the spigots 11.sup.a are obtained 
by a press operation, rotary extrusion or any other forming operation or 
hot or cold deformation (forging). According to another embodiment, the 
spigots 11.sup.a may be assembled with the planar portions 2.sup.a and 
rendered rigid with the latter by any means such as welding, riveting, 
screwing or adhesion. In any case, the thickness of the planar portions 
2.sup.a and the thickness of the walls of the spigots 11.sup.a need not be 
the same. This is in particular so when the spigots 11.sup.a are obtained 
by a press operation from a planar blank blanked from sheet steel. Note 
also that the formed part has a rounded edge 4.sup.a at the top of the 
bore of the cylindrical spigot 11.sup.a resulting from the flow of the 
metal in the course of the press operation. With such plates an inner link 
similar to that shown in FIG. 6 may be formed. FIG. 14 shows a chain 
formed by such inner links which are interconnected by outer links 
identical to those shown in FIG. 13. In such a chain, the inner plates 
1.sup.a are free and their lateral displacements are limited inwardly only 
by the rollers 8.sup.a and outwardly only by the outer plates 9. 
FIGS. 7, 8 and 15 show how the conventional outer links may be replaced by 
links formed by outer plates having spigots. Such plates 1.sup.b comprise 
two part-circular portions 2.sup.b interconnected by a planar portion 
4.sup.b, but the latter does not have divergent edge portions. The portion 
2.sup.b has a hollow cylindrical spigot 11.sup.b with a rounded edge 
12.sup.b at the top of its bore. In a preferred embodiment of the 
invention, the spigots 11.sup.b are asymmetrical, that is to say longer on 
the longitudinally innermost side of the spigot than on the outermost side 
thereof as shown in FIG. 8. This feature permits limiting the wear of the 
chain by concentrating the metal in the stressed part of the plate which, 
in its outer plate location in the chain, is subjected solely to tensile 
stresses. Two outer plates 1.sup.b rendered rigid with each other by solid 
spacer members 10 or hollow spacer members 10' which are a drive fit in 
the spigots 11.sup.b and in no way subjected to the forces to which the 
chain is subjected and merely serve to render the outer plates 1.sup.b 
rigid with each other, form the outer link of a chain such as shown in 
FIG. 15 in which the inner links are formed with inner plates 1.sup.a. As 
the spacer members 10 or 10' are not under tensile stress they may be made 
lighter relative to spacer members of known chains. Moreover, the rounded 
edge 12.sup.b of the spigots enable the spacer members to be riveted 
without however extending beyond the outer surface of the plate for 
example more than 1/10 to 2/10 mm. 
With reference now to FIGS. 9 and 10, the inner plates 1.sup.c are similar 
to the plates shown in FIGS. 3 and 4, but have an asymmetrical outer 
shape, namely a side 13.sup.c which is much more deeply notched than the 
other side 14.sup.c. These plates 1.sup.c moreover have all the features 
of the plates 1.sup.a, namely divergent edge portions 5.sup.c, symmetrical 
hollow cylindrical spigots 11.sup.c and a planar median portion 4.sup.c 
interconnecting two planar part-circular portions 2.sup.c in the same 
plane as the latter so that the portions 2.sup.c and 4.sup.c define inner 
faces for the link which are contained in a common plane. 
Likewise, the outer plates 1.sup.d of FIGS. 11 and 12 are similar to the 
outer plates 1.sup.b of FIGS. 7 and 8, but have an asymmetrical profile 
with a side 13.sup.d much more deeply notched than the other side 
14.sup.d. These plates 1.sup.d also have all the other features of the 
plates 1.sup.b, namely a planar center portion 4.sup.d interconnecting two 
part-circular portions 2.sup.d which carry hollow cylindrical spigots 
11.sup.d which are preferably asymmetrical as shown. 
FIG. 16 shows how the plates 1.sup.c and 1.sup.d are mounted in the chain 
in reversed relation in each link, the notched side of one plate facing in 
the opposite direction to the notched side of the other plate. The 
features and advantages of this assembly are explained hereinafter. In 
devices for changing speed or gear by means of a derailleur, a certain 
number of sprockets having a decreasing number of teeth, usually 3, 5 or 
7, are assembled on the rear hub. These sprockets form an ascending or 
descending stair-like arrangement which the chain must travel across to 
change speed. The arrangement adopted for the plates 1.sup.c and 1.sup.d 
of the chain permits choosing for the mounting of the chain the suitable 
direction so that in the direction for changing up the speeds, the plates 
are as notched as deeply as possible. This has for effect to require, when 
shifting the chain, a minimum raising thereof for passing from one 
sprocket to the immediately higher sprocket. In the other direction for 
changing down the speeds, on the contrary the chain must be guided 
laterally, which function is performed by the unnotched side of the 
plates. Moreover, the divergent shape of the inner link plates facilitates 
in both cases (changing up or changing down the speeds) the positioning of 
the chain on the teeth of the sprocket (engagement). Further, this action 
may be completed by internally bevelling the median part of the outer 
plates. 
FIGS. 17 to 19 show an inner plate 1.sup.e similar to the plate 1 and 
having two part-circular portions 2.sup.e each of which has an aperture 
3.sup.e for receiving a spacer bushing and interconnected by a centre 
portion 4.sup.e which is deformed throughout its width and offset in a 
plane parallel to the general plane of the plate defined by the two planar 
portions 2.sup.e, so that the center portion 4.sup.e defines an inner face 
in the link which face is contained in a plane which is parallel to but 
laterally offset outwardly of the link relative to the plane in which the 
inner faces of the portions 2.sup.e are contained. The deformed center 
portion 4.sup.e has in longitudinal section a very wide V-shape having a 
flat bottom and an evolutive profile. Two plates 1.sup.e such as that just 
described may be assembled in the same way as the plates 1 to form an 
inner link of a transmission chain. The inner links formed in this way are 
interconnected by outer links which may be constructed in the conventional 
manner or in the manner described hereinbefore. 
As in the case of the plate 1, the center portions 4.sup.e, which are 
offset laterally outwardly of the link, define on the latter an entrance 
or lead-in which facilitates the engagement of the teeth of the sprocket 
in the chain. However, the lateral offsetting or deformation of the whole 
of the center portion 4.sup.e of the inner plate permits bringing a part 
of the inner face of the inner plate into approximate alignment with the 
inner face of the outer plate in the region in which the tooth of the 
sprocket engages in the chain. This facilitates the guiding of the chain 
and its engagement on the successive sprockets when changing speed with a 
derailleur. 
Reference will now be made to FIGS. 20 to 22 in which the same reference 
numerals as those of FIGS. 17 to 19, provided with the letter f instead of 
the letter c, have been used for designating similar parts. These FIGS. 20 
to 22 show an inner plate 1.sup.f similar to the plate 1.sup.e except 
that instead of having a single aperture, the part-circular planar 
portions 2.sup.f each have a tubular circular spigot 11.sup.f rigid with 
the planar portion 2.sup.f. These spigots are identical to those of the 
plate 1.sup.a and will therefore not be described in detail here. The 
plates 1.sup.f may be assembled in the same way as the plates 1.sup.a to 
form an inner link and a chain such as those shown in FIGS. 6 and 14 
respectively. 
FIGS. 23 to 25 represent an inner plate 1.sup.g for an inner link which 
differs from the plate 1.sup.e described above solely in the shape of its 
center portion. Indeed, the center portion of the inner plate 1.sup.g 
comprises a planar median part 4.sup.g which is deformed and offset in a 
plane parallel to the general plane of the plate defined by the two planar 
portions 2.sup.b and two lateral edge portions 5.sup.g which are also 
deformed and offset relative to the plane of the median part 4.sup.g. More 
precisely, these lateral edge portions 5.sup.g are offset relative to the 
plane of the median part 4.sup.g in the same direction in which said 
median part 4.sup.g is offset relative to the general plane of the plate 
so that, in the assembled position of two plates 1.sup.g to form an inner 
link, the lateral edge portions 5.sup.g are divergent laterally outwardly 
of the link and perform a function similar to that of the deformed edge 
portions 5 of the plate 1. The median part 4.sup.g defines an inner face 
in the link which face is contained in a plane which is laterally offset 
outwardly of the link relative to the plane of the inner faces of the 
portions 2.sup.b. Further, the plates 1.sup.g have apertures 3.sup.g in 
the portions 2.sup.g thereof and can be assembled to form inner links and 
transmission chains as described hereinbefore with reference to plate 1. 
FIGS. 26 to 28 illustrate a modification 1.sup.h of an inner plate which 
differs from the plate 1.sup.g solely in the presence of spigots 11.sup.h 
which are identical to the spigots 11.sup.f of the plate 1.sup.f. In these 
FIGS. 26 to 28, the same reference numerals as those of FIGS. 23 to 25, 
provided with a letter f instead of the letter g, are employed for 
designating similar parts. 
The plates 1.sup.g and 1.sup.h combine the advantages of the plates 1 or 
1.sup.a having deformed edge portions with the advantages of the plates 
1.sup.e and 1.sup.f having a deformed center portion.