Improvements in Devices for Transmitting or Arresting Rotary Motion.
Year: 1889

page_text: Date of Application, 23rd Dec., 1889
Complete Specification Left, 22nd Oct., 1890-Accepted, 29th Nov., 1890
PROVISIONAL SPECIFICATION.
Improvements in Devices for Transmitting or Arresting Rotary
Motion.
We, EDWARD SHAW, of Canons Marsh, in the City and County of Bristol,
Engineer, and GEORGE JOHN HARCOURT, of 5 Albert Villas, Clifton, Bristol
aforesaid, Gentleman, do hereby declare the nature of this invention to be as
follows:-
This invention relates to devices for transmitting or arresting rotary motion, and
consists partly in improvements in and developments of our invention for which
Letters Patent were granted to us, dated November 18th, 1887; No. 15871, that
is to say, in which, as therein set forth, a metallic coil is employed to grip or release
a body or bodies about which it is coiled, or within which it is wholly or in part
contained.
This invention consists, firstly, in an arrangement under which, in a clutch pulley,
clutch coupling or brake of the kind described in the Specification of our said former
Patent, a spring is employed to open the coil and a lever used to close it. The said
spring is contained within a recess provided for it in the flange of a collar carried
on the shaft.
The spring bears at one end against one of three arms on a bell-crank lever pivotted
on the collar, another arm being connected to the tail of the coil the head of
which is passed through a lug formed on the collar and may be provided with a
buffer spring beyond the lug. The spring aforesaid constantly exerts a pressure
upon one arm of the bell-crank lever which, in the absence of any counteracting force,
is thus tilted in such a direction that the coil is thereby expanded, that is to say,
prevented from gripping the boss of the pulley or other body about which it is coiled.
Adjacent to or on the collar is a ring to which is connected a hand lever, handle, or
its equivalent. By actuating the hand lever the ring may be moved axially on the
collar, and when the ring is brought to bear against the third arm, forming part of the
bell crank lever, the spring aforesaid is compressed and the coil closes on the boss of
the pulley.
For the purpose of enabling the effect of the movement of the ring to be
continued, although the compression of the buffer spring under increased stress
allows a movement of the coil and bell-crank to take place, a spring may be interposed
between the aforesaid ring and the outer end of that arm of the lever which is opposite
to the spring tending to close the coil. A second development comprised in this
invention consists in substituting, as an alternative means, a wedge, or block having
an inclined face, in lieu of a bell-crank lever, for acting upon the tail of the coil. The
wedge may be connected with the ring on the collar either through a rigid or elastic
connection. Under one arrangement the wedge is employed to cause the coil to grip,
and the release is effected by the action of a spring. Under another arrangement the
converse action is obtained. A third improvement constituting part of this invention,
and applicable to other forms of clutch, consists in so constructing a clutch that
liability to force the pulley out of truth on the shaft, through the exertion of any
unbalanced force, is reduced. This is effected by the provision of two bearings on the
shaft, between which bearings the gripping portion of the clutch is carried.
The space between the bearings may be formed into a chamber for receiving oil or
other lubricant.
A fourth improvement relates to means for causing the axial motion of the starting
ring or collar on the shaft for the purpose of influencing the gripping action
either of the friction device employed in this clutch, or those employed in other forms
of cintch

page_text: For this purpose two concentric rings are used, one ring being contained within
the other. The outer ring, which is kept in its place axially on the shaft by a
collar, is provided internally with portions of one or inore helical threads. These
threads fit into corresponding helical grooves formed on the periphery of the
inner ring.
Consequently, when the latter is rotated it is, by virtue of the helical threads, moved
at the same time axially along the shaft. The relative rotation is obtained either by
the use of a cranked rod and sliding block working in a groove in the inner ring,
or through the medium of a handle or equivalent device. This arrangement ensures
greater accuracy in movement, constraining an exact motion in the inner ring. The
construction may be reversed and the inner ring held while the outer ring moves.
A further improvement comprised in this invention relates to the attachment of
the coil to the body of a clutch, or to any like or analogous body.
Instead of securing the coil by one attachment only, it is preferred, in some
cases, to have two or more points of attachment so that the stresses may be
equalized and a balanced driving effect obtained, whether the coil presses against the
clutch body through a buffer spring, or directly. An adjustable screw, or its
equivalent, may be interposed between the clutch and the buffer spring or head of the
coil. To counteract any bending due to the direction of the pull of the coil and the
resistances of the buffer springs not being in a line, blocks are formed on the coil and
are arranged to bear axially to the shaft, against corresponding lugs on the clutch body.
The coil is, preferably, wrapped entirely round the bush, but it may be made to
overlap a cylindrical part on the clutch body having a diameter equal to that of the
bush. The foregoing descriptions relate more particularly to the case where the coil
grips by being contracted.
They apply, however, equally when the coil is made to grip by its expansion.
COMPLETE SPECIFICATION.
Improvements in Devices for Transmitting or Arresting Rotary
Motion.
We, EDWARD SHAW of Canons Marsh in the City and County of Bristol,
Engineer, and GEORGE JOHN HARCOURT of 5 Albert Villas Clifton Bristol afore-
said, Gentleman 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 devices for transmitting or arresting rotary motion, and
consists partly in improvements in and developments of our invention for which
Letters Patent were granted to us, dated November 18th 1887, No. 15871, that
is to say, in which, as is set forth in the Specification of the said Patent, a
metallic coil is employed to grip or release a body or bodies about which it is
coiled, or within which it is wholly or in part contained.
Now, this our present invention consists in an arrangement under which, in a clutch
pulley, clutch coupling or brake of the kind described in the Specification of our said
Patent No. 1871 of 1887 a spring is employed to open the coil and a lever employed
to close it. The spring is contained within a recess provided for it in the flange of a
collar carried on the shaft. The spring bears at one end against one of the three
arms of a bell-crank lever pivotted on the collar, another arm being connected to
the tail of the coil, the head of which is passed through a lug formed on the
collar and is provided with a buffer spring beyond the lug. The spring aforesaid
constantly exerts a pressure upon one arm of the bell-crank lever which, in the
absence of any counteracting force, is thus tilted in such a direction that the coil is
thereby expanded, that is to say, prevented from gripping the boss of the pulley or

page_text: other body about which it is coiled. Adjacent to or on the collar is a ring to which is
connected a handle or hand lever by actuating which the ring is moved axialle on the
collar, and when the ring is brought to bear against the third arın forming part of the
bell crank lever, the spring aforesaid is compressed and the coil closes.
For the purpose of enabling the effect of the movement of the ring to be continued
although the compression of the buffer spring under increased stress allows a move-
ment of the coil and bell crank to, take place, a spring is interposed between the
aforesaid ring and the arm of the lever which is opposite to the spring tending to close
the coil. By a set screw passed through this arm of the lever and bearing against the
collar the movement of the lever is limited for the purpose of causing the coil to open
automatically when the buffer spring is compressed to the requisite degree.
A second development comprised in this invention consists in the employment, as
an alternative means of controlling the tail of the coil, of a wedge or block having an
inclined face. The wedge is connected to the ring on the collar by a bolt and slipper.
Under this arrangement the coil is opened by the wedge, as a substitute for one part
of the bell-crank lever, when the slipper and holt are moved by the action of the ring.
The spring reverses the action when the pressure exerted through the ring is with-
drawn. By reversing the direction of the winding of the coil the converse action is
obtained.
A third improvement constituting part of this invention and applicable to other
forms of clutches, consists in so constructing a clutch that liability to force the pulley
out of truth on the shaft, through the exertion of any unbalanced force, is reduced.
This is effected by the provision of two bearings on the shaft, between which bearings
the gripping portion of the clutch is carried. The space between the bearings is
formed into a chamber for receiving oil or other lubricant.
A further improvement relates to means for causing the axial motion of the starting
ring for the purpose of influencing the gripping action of the gripping device
employed in the clutch.
For this purpose two concentric rings are used, one being contained within the
other. The outer ring, which is kept in its place axially on the shaft by a collar,
is provided internally with portions of one or more helical threads. These threads
fit into corresponding helical grooves formed in the periphery of the inner ring.
Consequently, when the latter is rotated, it is, by virtue of the helical threads,
moved at the same time axially along the shaft. The relative rotation is obtained
either by the use of a cranked rod and sliding block working in a groove in the
inner ring, or through the medium of a handle or the like.
The axial motion of the inner ring is obtained by a comparatively small circular
movement of the handle, but under a modification, in which a single helical thread
of slow pitch is used, a slower axial movement is imparted to the inner ring and
thus a more gradual control over the gripping power of the coil is obtained. The
construction may be reversed and the inner ring held while the outer ring moves.
A further improvement. comprised in this invention relates to the attachment of
the coil to the hody of a clutch, or to any like or analogous body. Instead of
securing the coil by one attachment only it is preferred in some cases, to have two
or more points of attachment so that the stresses may be equalized and a balanced
driving effect obtained whether the coil presses against the clutch body through a
buffer spring, or directly. An adjusting screw, or its equivalent, may be interposed
between the clutch and any buffer spring or between the clutch and the head of
the coil.
In the arrangements above described the conditions relate more particularly to
cases where the coil grips by being contracted, but it is to be understood that the
conditions apply equally when the coil is made to grip by its expansion.
Referring to the accompanying drawings Figures 1 and 2 illustrate one of the
improvements in gripping devices forming part of this invention, and shew its
adaptation to a clutch pulley P. To open the coil A. a spring k¹ is employed. To close
the coil a bell-crank lever g. g'e is used. The spring ¹ is contained within a recess
provided for it in the flange of a collar, d, carried on the shaft c. The spring k¹ bears

page_text: at one end against the arm g. of the bell crank lever which latter is pivotted on the
collar d. Another arin e of the lever is connected to the tail of the coil A, the head
of which is passed through a lug D formed on the collar and is provided with a
buffer spring C beyond the lug D. The spring constantly exerts a pressure upon
the arm g of the bell crank-lever g. g₁e which lever, in the absence of any counter-
acting force, is thus tilted in such a direction that the coil is thereby expanded, that
is to say, prevented from gripping the boss B of the pulley P. Adjacent to or on the
collar d. is a ring to which is connected a hand lever E. By actuating the hand
lever E the ring F may be moved axially on the collar d. and when the ring is
brought to bear against the third arm g' forming part of the bell crank-lever, the
spring ¹ is compressed and the coil A closes on the boss B of the pulley P. For the
purpose of enabling the effect of the movement of the ring to be continued,
although the compression of the buffer spring C under increased stress allows a
movement of the coil A and lever g, g'e to take place, a spring is interposed between
the ring F and the arm g' of the lever.
By a set screw h screwed in the arm g and bearing at its outer end against the
collar d the movement of the bell crunk lever is limited for the purpose of causing the
coil to open automatically when the buffer spring C is compressed to the requisite
degree.
At Figures 3. 4 and 5 is illustrated a second improvement in friction devices.
Under this arrangement a wedge is employed and substituted for the arm g'
(Figures 1 and 2) of the bell-crank lever and is an alternative means for controlling the
tail of the coil A. The wedge g¹ is connected to the ring F on the collar d through
the bolt j and slipper l. The coil A is opened by the wedge g¹ when the slipper land
bolt are moved by the action of the ring F. By the spring the action is reversed
If the direction of
when the pressure exerted through the ring F is withdrawn.
winding of the coil be reversed the converse action is obtained. The operation of the
rings FF is more fully set forth with reference to Figures 7 10 and 11.
A third improvement constituting part of this invention and applicable also to
other forms of clutches than those above described, consists in so constructing clutches
that liability to force the pulley out of truth on the shaft, through the exertion of any
unbalanced force, is reduced. This improvement is illustrated inore fully at Figures 6
7. 8. 9 and 10. The desired object is accomplished by the provision of two bearings R
on the shaft c between which bearings the gripping portion of the clutch, consisting
of the bush B and coil A, is carried. The space between the bearings R is made a
chamber for containing oil or other lubricant. This chamber is made by means of the
casing which enables the bearings R to be rigidly and truly bolted together by the
This arrangement provides also an easy method of carrying the bell-crank
In the Figures 7. 10. 11. 12. 13. 14. 15 and 16 is illustrated a mode of effecting
axial movement of the starting ring F on the shaft or, in this case, on one of the
bearings R, for the purpose of influencing the gripping action either of the friction
device employed in this clutch or those employed in other clutches. For this purpose
two concentric rings F. F¹ are used the ring F being contained within the ring F..
The latter is kept in its place axially on the shaft by a collar and is provided
internally with portions of one or more helical threads m.
bolts o.
lever.
'These threads fit into
corresponding helical grooves made in the periphery of the ring F. Consequently
when the latter is rotated it is, by virtue of the helical threads m, moved at the same
time axially along the shaft. The relative rotation is obtained either by the use of a
cranked rods and sliding block 9 (as seen at Figures 12 and 13) working in a
groover, in the ring F, or through the medium of a handle t, Figures 3. 4. 7
and 10.
The construction may be reversed, the ring F being held while the ring F¹ moves.
It will be seen that in Figures 3. 4. 7 and 10. the helical threads are short pieces
of rapid pitch. Three of these equidistant attached to the ring F and working in
helical grooves in the ring F are preferably used. The axial motion of the ring Fis
obtained by a comparatively small circular movement of the handle t.

page_text: Now in Figures 14 to 16 a single helical thread of slow pitch is used and, in
consequence, a slower axial movement is imparted to the ring F and thus a more
Rotation of the
gradual control over the gripping power of the coil is obtained.
ring F is obtained through the revolution of a worin H, Figures 14 and 15, which
gears into worm teeth on the outside of the ring F. The spindle J. carrying the
worm H has cut on it a thread carrying a nut K which engages with an index bar L.
which prevents the nut K from turning. This nut K serves two purposes. By
means of it the amount of wear taking place on the coil is detected since the
reading of the index at the moment when the coil commences to grip varies with
the wear of the coil, whilst at the same time the nut prevents more than a definite
number of revolutions being made by the handle M.
A further improvement comprised in this invention relates to the attachment of
the coil to the body of a clutch, or to any like or analogous body.
Instead of securing the coil A by one attachment only by the head x, as in
Figures. 3 and 5, it is preferred, in some cases, to have two or more points of attach-
ment as at x, y, Figs. 7. 8 and 10, so that the stresses may be equalized and a
balanced driving effect obtained, whether the coil presses against the clutch body,
as shewn, or through a buffer spring. An adjusting screw v, is interposed between
The coil is, preferably, wrapped
the clutch and the second head y of the coil.
entirely round the bush, as in Fig. 7, but it may be made to overlap a cylindrical
part on the clutch body having a diameter equal to that of the bush, as shewn
in Fig. 3.
The foregoing descriptions relate more particularly to cases where the coil grips by
being contracted. They apply, however, equally when the coil is made to grip by its
expansion.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is ;-
1. In a clutch, coupling, or brake (in which rotary motion is transmitted or
arrested by means of a metallic coil) the arrangement and construction of parts
herein before described with reference to Figs. 1 and 2, whereby external pressure
puts the coil into action, substantially as set forth.
2. In a clutch, coupling, or brake (in which rotary motion is transmitted or
arrested by means of a metallic coil the provision of a wedge or inclined block
operated from a starting ring to open or close the coil, substantially as herein before
described with reference to Figs. 3. 4 and 5 of the accompanying drawings.
3. In a clutch, coupling or brake (in which rotary motion is transmitted or arrested
through the medium of a metallic coil) the employment of two end bearings to the
friction device between which bearings the gripping part of the appliance is situated,
substantially as hereinbefore described with reference to Figs. 6. 7. 8. 9 and 10 of the
accompanying drawings.
4. The employment of rings F. F with a helical thread or threads and corresponding
groove or grooves, as hereinbefore described and shown at Figs. 3. 4. 7. 10. 12. 13.
14. 15 and 16 of the accompanying drawings, whereby when the starting lever of
the appliance is actuated, axial motion is imparted to one of the rings, as and for the
purpose set forth.
5. In a clutch, coupling or brake, in which a metallic coil is employed as the means
of gripping, securing the said coil at the driving end by two or more attachments, as
hereinbefore described with reference to Figs. 7. 8. and 10, whereby the pull of the
coil is more evenly balanced.
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