Improvements in or relating to Clutches.
Year: 1899

page_text: FRUVIDIONAL DEVIFICATION,
Improvements in or relating to Clutches.
I, HERBERT JELLEY, of Hillcross House, Coventry, in the County of Warwick,
Works Manager, do hereby declare the nature of this invention to be as follows:-
This invention relates to clutches which may be used for many different pur-
poses, but it is particularly applicable to driving mechanism for cycles, motor-
cars and the like, and I will now describe it as applied to the chain ring of a
bicycle for the purpose of providing what is now commonly known as a free
wheel that is, a wheel which is directly driven by the chain but can overrun
the chain should the speed of the bicycle exceed that at which the rider is
pedalling.
وو
In the application to the chain ring of a bicycle hub the chain ring itself is
made to rotate freely upon the hub which latter is provided with a ratchet wheel
or equivalent device working in a recess in the chain ring. One or more recesses
or pockets are formed in the chain ring as extensions of the circular recess in
which the ratchet wlieel works and in each of these pockets is a pawl of the
following construction.
The pawl is formed at one end to engage with the ratchet teeth in the well-
known manner, the other end engaging with a portion of the pocket in which it
lies. The inner face of the pawl may be curved and is intended to be in contact
with the teeth of the ratchet as they pass, the back end of the pawl being so
formed that as the tooth of the ratchet passes it it of necessity presses down the
other or operative end of the pawl so that should the ratchet be reversed this tooth
must come into engagement with the operative end of the pawl. I prefer to have
the pawl quite loose in its pocket so as to avoid the necessity for pins or pivots or
other centres upon which it would work although these latter may be used if
ferred. I find that the pawl will rock conveniently upon a knife edge or equi-
valent bearing suitably placed and that this may be conveniently provided by
thickening the back end of the pawl and forming a slight additional recess in the
pocket to receive it so that the shoulder formed upon the pawl by this thickened
portion engages with the corresponding shoulder in the back of the pocket. How-
ever, other dispositions of the pawl may be effected so long as the necessary rock-
ing movement is obtained:
pre-
With the construction described it will be seen that the pawl is independent
of any spring or the action of gravity in its operation. Any cover or equivalent
may be employed to enclose the pawls, ratchet wheel, etc., and they may run in
an oil-bath if preferred. Any desired number of the pawls may be used.
Deted this 10th day of Jul 1899

page_text: Improvements in or relating to Clutches,
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I, HERBERT JELLEY, of Hillcross House, Coventry, in the County of Warwick,
Works Manager, do hereby declare the nature of this invention and in what
manner the same is to be performed; to be particularly described and ascertained
in and by the following statement:-
This invention relates to pawl and ratchet clutches adapted for application to
any driving mechanism in which it is desired that one part shall be free to over-
run the other, and has for its object to provide a clutch in which the pawls after
having been thrown back by a passing tooth of the ratchet are again automati-
cally brought into the operative position without the aid of gravity or springs.
In carrying out this invention as applicable to free wheel mechanisms of cycles,
the clutohis-mounted in an annular recess within the rear sprocket, wheel, the
ratchet being formed upon some part operatively connected to the road wheel.
Pockets are provided in the sprocket wheel to carry pawls, so arranged in rela-
tion to the ratchet, that as one tooth of the ratchet travels past one end of the
pawl it depresses that end and places the opposite end in a position where it is
ready to engage the preceding tooth of the ratchet. As the tooth continues its
movement past the pawl, it depresses the end formerly raised by it, and raises
that end which it has passed. By this means the pawl is continually oscillated
as each tooth passes it, but being always in such position that it is ready to engage
that tooth of the ratchet which has last passed it. To permit the pawl to oscil-
late in the manner described above it may be pivotted to the sprocket wheel by
means of a knife edge or other device, and the various parts of the clutch may con-
veniently be kept in place by side plates in the usual well-known manner.
Figure 1 is a side elevation of a clutch constructed according to this invention',
and
Figures 2, 3, 4 and 5 are detail views of the same.
i)- 1
Figure 6 is a view similar to Figure 3 of an alternative construction according
to this invention.
Like letters indicate like parts throughout the drawings.
'
از
The clutch shown in the accompanying drawings is of the kind referred to
above as 'adapted for application to a bicycle as a free wheel clutch, and is formed
within the rear sprocket wheel A, which for this purpose is provided with an
annular recess A. Within the recess A' is a ratchet B which may be secured'
to the hub, or other part of the bicycle wheel to which power is to be applied, in
any well-known manner. In addition to the annular recess A¹ the sprocket
wheel A has one or more pockets A2 adapted to receive a pawl C. The pawl C is
provided with a cam-shaped portion or projection C¹, and on its inner face is
curved in such a manner that it is in contact with the teeth of the ratchet as they
pass, and on that side which is remote from the ratchet is arranged a knife edge C³,
(see Figure 5). The pocket A is in the construction illustrated by Figures 1 to 5
so shaped as to form a bearing for the knife edge C2 of the pawl and' is preferably
cut deeper at each end than in the middle so that the pawl may be free to oscil-
late about the knife edge. The operative end of the pawl or that end remote
from the cam C is provided with a recess C adapted to engage the teeth of the
ratchet B. The sprocket wheel A may be kept in position upon the ratchet B and
the pawls C kept in place in any convenient manner, such as by the side plates 'D
secured to the sprocket wheel by screws D...
'
The operation of the device is as follows:
In Figure 1 the pawls C are shown in engagement with the ratchet B so that
the sprocket wheel A when revolved in the direction indicated by the arrow, will

page_text: drive the ratchet and thus revolve the part to which the same is attached. If now
the sprocket wheel is held stationary the ratchet will over-run the sprocket in
the direction indicated by the arrow upon it.. In doing this one of the teeth will
approach the end C of the pawl, whilst the other is about to leave the end C³,
as shown in Figure 2. The tooth passing the end C (as shown in the figure
referred' to) has pushed that end back into the pocket A2 and has thus raised the
end upon which is the cam C. It is obvious therefore that when the tooth has
entirely passed the end C the following tooth will be brought into contact with
the cam C and will press that end of the pawl back into the pocket, whilst the
end C is displaced from the same and takes the position shown in Figure 3, so
that it is again ready to engage that tooth of the ratchet which has just passed
the end C3. It will be seen that by these means the pawl C is continually oscil-
lated about the knife edge C³, as each tooth passes it; the operative end of the
same being first raised to allow a tooth to pass and then immediately brought
down into its operative position by the next tooth so as to be ready for engage-
ment, the device being thus entirely independent of the action of gravity or
springs.
It will be understood that the clutch may be variously modified without depart-
ing from the nature of the invention, for instance, the pawls might, if desired, be
pivotted to the part A of the clutch, by means other than the knife edge C
described above; or the convex curve shown in the drawings on that side of the
pawl remote from the ratchet may be continued throughout its length, the base
of the pocket being curved in an opposite sense e. as a coucavity, so that the
pawl may oscillate or roll upon it without the aid of pivots, this modification being
illustrated by Figure 6.
It is obvious also that the ratchet teeth may be formed on the interior of the
sprocket wheel, the pawls C being in this case carried by the part B.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is:-
1. In a pawl and ratchet clutch a pawl which has a cam at one end, is pivotted
intermediate of its ends and which each of the ratchet teeth.as.it passes first moves
into operative position and then returns to inoperative position.
2. In a pawl and ratchet clutch a pawl which has a knife edge engaging an
angular recess in the clutch and is so disposed that each of the ratchet teeth as it
passes first moves it into operative position and then returns it to inoperative.
position substantially as described.
3. In a pawl and ratchet clutch a pawl operated in the manner described and
curved to roll on a correspondingly curved surface whereby pivots are dispensed
with.
4. The complete clutch substantially as described or illustrated in the accom-
panying drawings.