Derailleur for a bicycle

A derailleur for a bicycle, which comprises a base member, a movable member and two linkage members carrying the movable member therewith in the relation of being swingingly movable with respect to the base member, a control member swinging independently from the movable member, a pair of plates for energy-storing, which sandwich therebetween one of the linkage members and cooperate with the control member through an engageable projection thereof and a positioning and maintaining member provided between the control member and one of the base member, movable member and two linkage members for positioning the driving chain guide cages with respect to any one of a plurality of sprockets whereby the speed change stage can preliminarily be selected when the bicycle is at a standstill or while running when not pedalling.

This invention relates to a derailleur for a bicycle, and more particularly 
to a derailleur operable to selectively introduce a driving chain to one 
of three to five sprockets of a multi-speed transmitting freewheel which 
is mounted to a rear wheel hub of the bicycle. 
Generally, this kind of derailleur, which is divided into the so-called 
linkage and rod types, is composed of a base member, a movable member 
having chain guide cages and linkage members through which the movable 
member is connected with respect to the base member. The derailleur as is 
well known, is operated by a control wire to introduce the driving chain 
to a selective one of the sprockets in such a manner that an operating 
lever pulls the control wire to allow the movable member to be swingingly 
movable against a spring force or restored by the spring force, which 
spring force comes from a return spring provided to urge the movable 
member unidirectionally. Alternatively, two control wires may be used, 
each of which is pulled to move either direction the movable member. 
The conventional derailleur has no mechanism for positioning the chain 
guide pulleys carried on the movable member with respect to a selective 
one of the sprockets so that a cyclist is obliged to select the proper 
position of the pulleys only by his touch. Hence the conventional 
derailleur has the problem in that the driving chain is not exactly 
introduced for changing the bicycle speed and further it is impossible for 
it to be introduced unless the chain is travelling across a front gear and 
a rear wheel of the bicycle. 
A derailleur is known in U.S. Pat. No. 3,974,707 with a means for properly 
positioning and maintaining the chain guide pulleys with respect to the 
sprocket, thereby always exactly introducing the driving chain to a 
selective one of the sprockets for changing the bicycle speed. 
The invention of U.S. Pat. No. 3,974,707, however, has the problem not yet 
solved in that the speed change, even though exactly controllable, is 
unable to be performed when the bicycle is standing still or moving 
without pedalling. 
To solve the abovementioned problem, a derailleur was designed to introduce 
the driving chain always exactly and preliminarily select the desired 
speed change stage for changing the speed regardless of being at a 
standstill or moving. 
In other words, the derailleur of U.S. Pat. No. 3,974,707 has added to it 
one or more control members movable separately from other members. The 
control member is operated by either a control wire or its surrounding 
cable so as to move the movable member and is provided with a spring means 
urging the movable member in its moving direction. The aforesaid 
positioning and maintaining means is provided between the control member 
and one of the base member, movable member and linkage member, or between 
the control members so that when the movable member is subjected to a 
resistance against its movement in excess of the prescribed range, the 
control member only is moved against the spring force to energize the 
spring and then the movable member, when the resistance is released 
therefrom, is moved by restoration of the energized spring to be 
positioned at the preselected speed change stage. Thus, the bicycle speed 
is changeable when the bicycle is at a standstill or moving while not 
pedalling and the speed change is preselective. Such a derailleur, 
however, is complicated in construction and expensive to manufacture for 
the preselection from low speed to high speed and vice versa, and has a 
problem in that the positioning and maintaining means is not adjustable to 
properly position the movable member with respect to the base member. 
The present invention has been designed to improve the derailleur of the 
abovementioned previous inventions in order to solve the problems thereof. 
A main object of the invention is to provide a derailleur of simple 
construction which is capable of changing the bicycle speed from low to 
high and vice versa while the bicycle is not moving or moving without 
pedalling and is capable of having the positioning and maintaining means 
adjusted to properly position the movable member with respect to the base 
member. Another object is to provide a derailleur capable of surely 
carrying out the preselection even with the foregoing adjustment. 
The invention is characterized in that the control member is provided in 
addition to the base member, movable member and two linkage members with a 
pair of plates for energy-storing to sandwich therebetween one of the 
linkage members in the relation of being movable close to or apart 
therefrom; and an engageable projection formed at the control member to be 
engaged with between the plates; a spring provided between the plates to 
urge the plates toward the one linkage member; and a positioning and 
maintaining means provided between the control member and one of the 
derailleur components, such as the base member and movable member, so that 
one of the plates is shifted to deform the spring to be energized when the 
movable member is, against its movement, subjected to a resistance in 
excess of the prescribed range, and when the resistance is released, the 
energized spring force allows the movable member to shift to the desired 
speed-change stage. 
Furthermore, the improvement of the invention is characterized in that the 
linkage member between the plates in the aforesaid construction is 
provided with an adjustable screw whose head and end abut against the 
plates respectively so that the adjustable screw may be adjusted to 
properly position the movable member with respect to the base member 
through the positioning and maintaining means. The head and the end faces 
of the screw are rounded to form a partial imaginary circle, whereby the 
extent of the spring deformation, i.e., the energized spring force, is 
made constant in the preselection by the plate displacement even after the 
screw is adjusted to properly position the movable member. This always 
ensures proper reselective control.

The derailleur of a linkage type is shown in FIGS. 1 and 2, which basically 
comprises a base member 1, two parallel linkage members 5 and 6 and a 
movable member 9. The base member 1 comprises a bracket 1a fixed to the 
bicycle frame fork end (not shown) together with a hub shaft (not shown), 
a support 1b mounted to the bracket 1a through a pivot 2 in a rotatable 
relation within a given range only. The support 1b is swingable with 
respect to the bracket 1a through the pivot 2 but rigid in the moving 
direction of movable member 9, and has at one side two opposite tongues 
pivotally supporting the members 5 and 6 therewith through two pins 3 and 
4. 
The linkage members 5 and 6, equal in length and of a C-like section 
respectively, are mounted to the support 1b of the base member oppositely 
to each other at each open side of the same. 
The movable member 9 is formed like the support 1b to have at its one side 
two opposite tongues and is pivotally supported on the two tongues to the 
free ends of linkage members 5 and 6 through pins 7 and 8. At the other 
side of the movable member 9 is mounted cages 11 carrying two chain-guide 
pulleys 11a through a pivot 10 turnable in a given range only. 
The chain-guide pulleys 11a carry a driving chain (not shown) thereon and 
move in the axial direction of the multi-speed transmitting freewheel (not 
shown) so as to cause the driving chain to engage with a selected 
freewheel for changing the bicycle speed. 
The basic construction of the derailleur as described is not different at 
all from well-known derailleurs. 
The invention is directed to provide in the derailleur a control member 12 
moving independently of the movable member 9; a pair of plates 22 and 23, 
serving as an energizer, sandwiching the linkage member 5 in the relation 
of being movable toward or away therefrom, which plates have engaged 
therebetween an engageable projection 26 formed at the control member 12 
and are urged by a spring 24 toward the linkage member 5; and a 
positioning and maintaining means 13 provided between the control member 
12 and one of the movable member 9 and the base member 1; so that the 
control member 12 may be moved against the spring 24 force when the 
resistance against the speed change caused by non-travelling of the drive 
chain is greater than the resistance against speed change when the chain 
is travelling. The restoration of the spring 24, when the resistance is 
released due to the drive chain starting to travel, may allow the movable 
member 9 to be moved to a desired speed change stage by means of the 
positioning and maintaining means 13. 
In greater detail, the control member 12 is of a substantially L-like 
shape, has one arm bored at 12a and is mounted to the movable member 9 
through the pin 7 inserted into the bore 12a in the relation of being 
swingable with respect to the movable member 9. The other arm of control 
member 12 bends at substantially the intermediate portion of the linkage 
member 5, projects outwardly of the linkage member 6, and has a fitting 
12b for securing thereto one end of a sheath of a control wire to be 
hereinafter described. 
The positioning and maintaining means 13 comprises a retainer 15 carrying a 
first cooperating means 14 of a rolling body, an adjuster 16 mounted to 
the retainer 15, and an extension 17 defining a plurality of engaging 
portions 17a. 
The extension 17 is either of a plate incorporated with the movable member 
9 or formed of a separate member fixed to movable member 7. The extension 
17 extends at its rearmost end toward the base member 1 and terminates at 
substantially the base of the linkage members 5 and 6. At the rearmost end 
of the extension 17 are provided a plurality of engageable portions 17a 
which correspond in number to every speed-change stage along the path of 
the retainer 15 when changing the bicycle speed. 
The second co-operating means 17a are composed mainly of through holes or 
recesses formed in the extension 17. The through holes, as shown in FIG. 
3, are formed in a dish-like shape with one side open respectively so that 
each interval between two adjacent holes becomes a chevron shape. Hence, 
the first co-operating means 14 of the retainer 15, when located on the 
slope of the interval, may slip down into any one of the second 
co-operating means 17a to be engaged therewith. 
The retainer 15 is formed of a strip, such as a leaf spring, having one end 
fixed to the control member 12 through a pin 18, and the other end 
extending to the rearmost end of the extension 17 and has a pair of 
tongues 15a, 15a formed by cutting from the same. The first co-operating 
means 14 is a ball with stems or a roller, supported on tongues 15a, 15a 
of the retainer 15 through the stems so as to be urged elastically toward 
each of the second co-operating means 17a. Also, at an intermediate 
portion of the retainer 15 there is mounted the adjuster 16 employing a 
screw-threaded member, such as a headed screw bolt, which adjuster passes 
through the retainer 15 at the intermediate portion thereof and is screwed 
at its end into the control member 12, so that the first co-operating 
means 14 may be adjustably urged toward the second co-operating means 17a. 
Thus, the first co-operating means 14 engages with any one of the second 
co-operating means 17a so that the movable member 9, or the drive chain 
guide cages 11, are positioned with respect to the base member 1 and kept 
at the position corresponding to the desired speed change stage. 
The movable member 9 is controlled by a control cable 19 comprising a wire 
19a of relatively large diameter and little flexibility, the so-called 
push-pull type wire, and a sheath 19b for guiding the wire 19a, the wire 
19a being supported at its one end to a fitting 20 of the movable member 9 
and at the other end to an operating lever (not shown) fixed to the 
bicycle handle bar, the sheath 19b being fixed at its one end to a fitting 
12b at the foremost end of the control member 12 and at the other end to a 
fixed plate of the operating lever. 
Although the single push-pull type wire is preferred to be used as the 
control wire 19a for allowing the movable member to be moved for changing 
the speed, wires of other types may be used. 
The pair of plates 22 and 23 sandwiching therebetween the linkage member 5 
are pivotally supported at each one end thereof by the pin 7. The spring 
24 is coiled at its intermediate portion so as to be supported by the pin 
7 and seated at one end to the outer lateral surface of plate 22, and at 
the other end to plate 23 so that both the plates 22 and 23 are urged by 
the spring toward the linkage member 5. 
Also, the linkage member 5 is provided with an adjustable screw 25 whose 
head 25a and end 25b forcibly abut against the plates 23 and 22 
respectively, so that the adjustable screw 25 screwably controls the 
proper positioning of movable member 9 by the positioning and maintaining 
means 13 with respect to the base member 1. 
In greater detail, when the driving chain carried on the chain-guide 
pulleys 11a of the cages 11 is out of position with respect to the 
sprockets of the multi-speed transmitting freewheel for changing the 
bicycle speed, the adjust-screw 25 is screwed toward the one plate 22 as 
shown in FIG. 6, whereby the plate 22 is pushed by the screw end to 
tighten the coils of the spring 24 of which one end is seated on the plate 
22, while, the other plate 23 is pushed through the other end of the 
spring 24 by the force corresponding to the coil-tightening force. As a 
result, the linkage member 5 is pushed by the plate 23 downwardly around 
the pin 3 as shown in FIG. 4, to move the movable member 9 downwardly. To 
the contrary, when the adjustable screw 25 is unscrewed as shown in FIG. 7 
from its conditions as shown in FIGS. 5 and 6, one end of the spring 24 
seated on the plate 22 is subjected to the biasing force corresponding to 
that applied to the other plate 23 by the screw head being unscrewed to 
tighten the coils of the spring 24, whereby the link member 5 is turned 
upwardly around the pin 3 as shown in FIG. 4 through the biased plate 22 
to result in moving upwardly the movable member 9. 
The adjustable screw 25 is so formed that its head surface 25a and end face 
25b are made round along an imaginary circle X as shown by the phantom 
line in FIG. 5, whereby the spaced interval between the plates 22, 23 
swinging around the pin 7 and the distance between the tips of the head 
and end of the adjustable-screw 25 are kept constant when adjusting the 
movable member 9 to be properly positioned with respect to the base member 
1. In addition, the head 25a of the screw 25 abuts the plate 23 through a 
slot 23a smaller in width than the diameter of the head so that the screw 
25 is adjustable by use of a tool, such as a screwdriver, inserted through 
an eye-hole 6a formed in the linkage member 6 opposite to the plate 23 
(FIG. 4). 
The projection 26 engageable between both the plates 22 and 23 for 
energy-storing, serves to shift one plate with respect to the other. The 
projection 26 of a rod-like shape, fixed at its base to the control member 
12, extends through the extension 17 to enter into a cutout 5a formed at 
the substantially intermediate lower portion of the linkage member 5, and 
abuts at its periphery against the inner surface of each end of the plates 
22, 23. The extension 17 is provided with a slot 17b for receiving the 
projection 26 therein, which slot is formed arcuately around the pin 7, so 
that the projection 26 is movable along the arcuate slot 17b together with 
the control member 12 with respect to the extension 17. 
In the abovementioned construction, when the driving chain carried on the 
chain-guide pulleys 11a of the cages 11 is in mesh with the high speed 
sprocket of the multi-speed free-wheel, the movable member 9 is positioned 
as shown in FIG. 2, and maintained at the position where the first 
co-operating means 14 of the positioning and maintaining means 13 is 
engaged with the outermost one of the engageable portions 17a at the 
linkage member 5 side. 
In the instance, when the movable member 9 is subjected to the resistance 
within a predetermined range, the driving chain is introduced from the 
high speed sprocket to the low speed sprocket through the chain guide 
cages 11 in such a manner that the operating lever pulls the wire 19a to 
bring the fitting 20 thereof close to the fitting 12b of the sheath 19b so 
that the first co-operating means 14, as shown in FIG. 8, is engaged with 
the outermost second co-operating means 17a at the linkage member 6 side 
the movable member 9 is pushed fully to be displaced with respect to the 
base member 1, where the plates 22, 23 for energy-storing are in 
engagement with the engageable projection 26 through the spring 24 to be 
moved together with the linkage member 5 but not displaced thereagainst. 
In changing from low speed to high speed, the wire 19a is pushed to bring 
the fitting 20 apart from the fitting 12b so that the first co-operating 
means 14 is engaged with the outermost second co-operating means 17a at 
the linkage member 5 side the movable member 9 is fully restored with 
respect to the base member 1. 
The speed change when the movable member 9 is subjected to a resistance 
exceeding the predetermined range will be described hereinafter. First, 
the driving chain is changed from the high speed sprocket to the low speed 
sprocket through the driving chain guide cages 11 in such a manner that 
the operating lever pulls the wire 19a to swing the control member 12 
around the pin 7 as shown in FIG. 8, but does not move the linkage member 
5 because the movable member 9 and the linkage member 5 pivoted thereto 
are restricted from being moved by the resistance applied thereto. The 
engageable projection 26 moves along the arcuate slot 17b in the direction 
away from the linkage member 5. Hence, the moved projection 26 allows the 
plate 23 to be displaced with respect to the linkage member 5 as shown in 
FIG. 9 and the first co-operating means 14 of the positioning and 
maintaining means 13 is engaged with the outermost second co-operating 
means 17a at the linkage member 6 side and also the displaced plate 23 
compresses the spring 24 to store the spring reactive force in both the 
plates 22, 23. Under this condition, when the resistance is released from 
the movable member 9, the stored energy at the plates 22, 23 is released. 
When the driving chain is changed from the low speed sprocket to the high 
speed sprocket through the drive-chain guide cages 11, controlled by the 
wire 19a pushed by the operating lever, the resistance similarly restricts 
the movable member 9 and the linkage member 5 from movement around the pin 
7 to the position as shown in FIG. 2. The linkage member 5 is at rest, 
whereby the projection 26 is moved along the slot 17a from the position 
shown in FIG. 8 in the direction away from the linkage member 6. 
Hence, the moved projection 26 allows the plate 22 to be displaced with 
respect to the plate 23 as shown in FIG. 11, and the first co-operating 
means 14 is engaged with the outermost second co-operating means 17a at 
the linkage member 5 side. The displaced plate 22 compresses the spring 24 
to store its spring reactive force at the plates 22, 23. Under this 
condition, the stored energy of both the plates 22, 23, when the 
resistance is released from the movable member 9, allows the linkage 
member 5 to move toward the displaced plate 22 as shown in FIG. 12, to 
move the movable member 9, thus changing the driving chain from the low 
speed sprocket to the high speed sprocket. 
Further, when the driving chain is changed to one of the middle speed 
sprockets of the multi-speed transmitting freewheel, the wire 19a may be 
pulled or pushed to allow the first co-operating means 14 to be engaged 
with one of the intermediate second co-operating means 17a. 
In the aforesaid embodiment, the plates for energy-storing are mounted to 
the linkage member 5 in the relation of being swingable thereto, but they 
may be made perpendicularly movable with respect to the lengthwise 
direction of the linkage member. In brief, it is enough for the plates to 
be made movable toward or away from the linkage member 5. 
Alternatively, the control member 12, which is pivoted to the movable 
member 9 in the aforesaid embodiment, may be pivoted to the support 1b of 
the base member 1 through the pin 3 or 4. 
Furthermore, the positioning and maintaining means 13 may be provided 
between the control member 12 and the support 1b of the base member 1 
instead of between the former and the movable member 9. The control member 
12 if so pivoted to the support 1b and extension 17 extends from the 
support 1b toward the movable member 9 then the positioning and 
maintaining means 13 may be mounted between the control member 12 and the 
extension 17. 
In summary, the derailleur of the invention is provided with four members 
i.e., a base member, two linkage members and a movable member having the 
driving chain guide cages; a control member carrying therewith either wire 
or a sheath of the control cable and movable independently from the four 
members; a pair of plates for energy-storing, which are provided to 
sandwich one of the linkage members therebetween in a relation of being 
movable toward or away from the one linkage member and are urged toward 
the one linkage member by means of a spring. A projection formed at the 
control member engages between the plates; and the positioning and 
maintaining means is provided between the control member and one of the 
four members. Hence, the derailleur, simple in construction, is 
advantageous in that the speed change from low to high and vice versa by 
use of the control cable is made certain even when the movable member is 
subjected to a resistance over the prescribed range against its movement. 
The driving chain, when the resistance is released from the movable 
member, can be introduced automatically to a selected sprocket by means of 
the energy stored in the plates and also exactly and properly done by the 
positioning and maintaining means. 
Also, the derailleur is advantageous in that an adjustable screw, which is 
attached to the linkage member abuts at its head and end against both the 
plates respectively and is adapted to adjust the linkage member or the 
movable member by the positioning and maintaining means so that the 
driving chain guide cages carried by the movable member may be exactly 
adjusted in position with respect to the multi-speed transmitting 
freewheel simply by screwing the adjustable screw. 
Furthermore, the adjustable screw, whose head surface and end face are made 
round along an imaginary circular line, makes it possible to approximately 
equalize the urging forces applied to the head and end through both the 
plates for energy-storing when adjusted to properly position the movable 
member with respect to the base member. 
While an embodiment of the invention has been shown and described, the 
invention is not limited to the specific construction thereof, which is 
merely exemplified in the specification rather than defined.