IMPROVEMENTS IN FRICTION CLUTCHES
Year: 1875

page_text: LETTERS PATENT to John Imray, of No. 20, Southampton Buildings,
Chancery Lane, in the County of Middlesex, for the Invention of
"IMPROVEMENTS IN FRICTION CLUTCHES."
Sealed the 28th April 1876, and dated the 3rd November 1875.
PROVISIONAL SPECIFICATION left by the said John Imray at the
Office of the Commissioners of Patents, with his Petition, on the
3rd November 1875.
I, JOHN IMBAY, of No. 20, Southampton Buildings, Chancery Lane,
in the County of Middlesex, do hereby declare the nature of the said
Invention for " IMPROVEMENTS IN FRICTION CLUTCHES," to be as follows :—
My Invention relates to friction clutches applicable in lieu of ratchets
and pawls, silent feeds, and like mechanism for clutching a lever or
wheel to a shaft or spindle when revolving in one direction, and releasing
it when moving in the opposite direction. Such friction clutches can be
applied in many cases, as for example to the working of ratchet braces,
to the feed of saws, planing machines, and other machinery having

page_text: reciprocating movement to clutch wheels on their shafts and to like
purposes.
In order that the nature of my Invention may be more clearly under-
stood I will explain a construction applicable to clutching a wheel on a
shaft in such a manner that when the wheel is driven in the one
direction it drives the shaft, but when it is driven in the other direction
it revolves freely on the shaft. On the one side of the wheel I fix a
collar on the shaft, against which collar the side of the wheel or of its
boss bears, and for the purpose of obtaining a better bite the bearing
surfaces may be coned or circularly grooved and corrugated. On the
other side of the wheel is a projecting boss on which is fitted a ring free
to revolve thercon, the said ring having one face bearing against the
side of the wheel or its boss, and these bearing surfaces may likewise be
coned or circularly corrugated. On the shaft at some distance from the
ring I fix a second collar, and between the ring and the collar I place
around the shaft two or more bars having rounded ends which enter
into rounded recesses provided in the outer face of the ring and on the
inner face of the second collar respectively. These bars are made a little
longer than the distance between the ring and the collar, so that when
they are placed in position between them they lie a little obliquely or at
a small inclination to the axis of the shaft. When the wheel is turned
in the one direction it tends to carry the ring with it and so to increase
the obliquity of the bars, thereby diminishing the pressure of the ring
against the wheel and of the wheel against the first collar, the wheel
being thus left free to revolve on the shaft without driving it; but when
the wheel is turned in the opposite direction it tends to carry the ring
with it and to bring the bars to a position more nearly parallel to the
axis of the shaft, which has the effect of pressing the ring forcibly
against the wheel, and the wheel against the collar on its other side,
producing friction such that the shaft is caused to turn along with the
wheel.
It may be readily understood that a like construction is applicable to
a handle or lever instead of a wheel upon the shaft, as for example in

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Imray in the Great Scal Patent Office on
the 1st May 1876.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
IMRAY, of No. 20, Southampton Buildings, Chancery Lanc, in the
County of Middlesex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Third day of November, in the year
of our Lord One thousand eight hundred and seventy-five, in the
thirty-ninth year of Her reign, did, for Herself, Her heirs and suc-
cessors, give and grant unto me, the said John Imray, Her special
license that I, the said John Imray, my executors, administrators,
and assigns, or such others as I, the said John Imray, my exccutors,
administrators, and assigns, should at any time agree with, and no
others, from time to time and at all times thereafter during the term
therein expressed, should and lawfully might make, use, exercise, and
vend, within the United Kingdom of Great Britain and Ireland, the
Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN
FRICTION CLUTCHES," upon the condition (amongst others) that I, the said
John Imray, my executors or administrators, by an instrument in
writing under my, or their, or one of their hands and seals, should par-
ticularly describe and ascertain the nature of the said Invention, and
in what manner the same was to be performed, and cause the same
to be filed in the Great Seal Patent Office within six calendar months
next and immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said John Imray, do hereby declare the
nature of the said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the
following statement thereof, reference being had to the accompanying
Sheet of Drawings, and to the figures and letters marked thereon, that
is to say :-
My Invention relates to friction clutches applicable in lieu of ratchets
and pawls, silent feeds, and like mechanism for clutching a lever or
wheel to a shaft or spindle when revolving in one direction, and releasing
it when moving in the opposite direction. Such friction clutches can
be applied in many cases, as for example to the working of ratchet
braces, to the feed of saws, planing machines, and other machinery

page_text: having reciprocating movement, to clutch wheels on their shafts and to
like purposes.
In order that the nature of my Invention may be more clearly understood
I will explain a construction applicable to clutching a wheel on a shaft,
in such a manner that when the wheel is driven in the one direction
it drives the shaft, but when it is driven in the other direction it
revolves freely on the shaft. On the one side of the wheel I fix a collar
on the shaft, against which collar the side of the wheel or of its boss
bears, and for the purpose of obtaining a better bite the bearing surfaces
may be coned or circularly grooved and corrugated. On the other side
of the wheel is a projecting boss on which is fitted a ring free to revolve
thereon, the said ring having one face bearing against the side of the
wheel or its boss, and these bearing surfaces may likewise be coned or
circularly corrugated. On the shaft at some distance from the ring I
fix a second collar, and between the ring and the collar I place around
the shaft two or more bars having rounded ends which enter into
rounded recesses provided in the outer face of the ring and on the inner
face of the second collar respectively. These bars are made a little
longer than the distance between the ring and the collar, so that when
they are placed in position between them they lie a little obliquely or at
a small inclination to the axis of the shaft. When the wheel is turned
in the one direction it tends to carry the ring with it and so to increase
the obliquity of the bars, thereby diminishing the pressure of the ring
against the wheel and of the wheel against the first collar, the wheel
being thus left free to revolve on the shaft without driving it; but
when the wheel is turned in the opposite direction it tends to carry the
ring with it and to bring the bars to a position more nearly parallel to
the axis of the shaft, which has the effect of pressing the ring forcibly
against the wheel, and the wheel against the collar on its other side,
producing friction such that the shaft is caused to turn along with the
wheel.
It may be readily understood that a like construction is applicable to

page_text: in one direction but to slip in the opposite direction; Fig. 2 is a plan of
the same; and Fig. 3, a transverse section on the line Z, Z.
A is a shaft on which is fixed a collar B; C is the wheel or pinion
which is to be clutched on the shaft A so as to revolve with it in the
one direction but to slip or revolve independently in the opposite
direction. On this wheel or pinion is a projecting boss c on which is
fitted a ring D. On the shaft A is fixed another collar E. Cup-shaped
recesses are formed in the faces of D and E, and into these are inserted
the rounded ends of bars G, of which there may be two, three, four, or
more arranged around the shaft. Each of the bars G is made a little
longer than the distance between their seats in D and E, so that when
the bars G are inserted in their places they lie somewhat obliquely or a
little inclined to the axis of the shaft, as shewn in Fig. 2. To prevent
the bars G from getting out of their places I prefer to provide a
flange F (which may be connected to the collar E, as shewn), having
holes through which the bars G are passed, these holes being slotted, as
shewn in Fig. 3, so as to allow the bars G to move a little to either side
of their middle position.
To explain the action of the clutch I will suppose that the pinion C
driven by some extraneous power has to revolve freely in the direction
of the arrow, Fig. 2, without driving the shaft, but that when it is driven
in the opposite direction it has to clutch the shaft or cause it to revolve
with it. It will be seen from Fig. 2 that when the wheel C revolves in
the direction of the arrow it tends to increase the inclination of the
bars G to the axis, and so to relieve the pressure of the ring D on the
face of the wheel; but should the wheel C be driven in the direction
opposite to the arrow, then as it tends to carry the ring D round with it
in the same direction it tends to move the bars G into positions more
nearly parallel to the axis, whereby they are made to press the ring D
against the wheel C and the wheel C against the collar B, and the
friction thus produced at the pressing surfaces causes the ring D and
collar B to revolve with the wheel C. In a similar manner if the
shaft A should be driven by extraneous power in the direction of the
arrow it would by tending to render the bars G more nearly parallel to
the axis cause the wheel C to revolve with it, but if driven in the
opposite direction it would revolve independently of C.
Ti
4. shame the annlication of a similar clutch in lieu of a ratchet

page_text: and pawl to form a silent feed for reciprocating machines, such as sawing
or planing machines. In this case H is a lever caused to reciprocate by
a cam, eccentric, or crank, its boss C is fitted with parts similar to those
already described and marked with letters corresponding to those used
for the like parts in Figs. 1, 2, and 3. When the lever H makes its
stroke in the one direction it does not turn the feed shaft A, but when
it makes its stroke in the opposite direction its boss C is squeezed
between B and D, and it then by its frictional hold causes the shaft A
to turn partly round along with it.
•
Fig. 5 represents a longitudinal section of a clutch like that described
above applied to work a drill brace in lieu of the ordinary ratchet and
pawl, the action in this case being similar to that of the feed clutch
shown in Fig. 4, that is to say, the hand lever H of the brace causes the
drill K to turn partly round when it is moved in the one direction but
leaves the drill K stationary while it makes its back stroke. The faces
of the boss C and of the collar B and ring D may be flat, as shewn in
the Drawings, or they might be made coned or circularly grooved or
corrugated so as to give a greater frictional hold.
Having thus described the nature of my Invention, and in what
manner the same is to be performed, I claim, the use of a friction clutch
in which the boss of a wheel or lever fitted to turn freely on a shaft is
clutched therewith for rotation in one direction by the movement of
bars inclined to the axis to a position more nearly parallel to the axis,
which movement produces frictional pressure between the boss and a
collar on the shaft, substantially as herein described.
In witness whereof, I, the said John Imray, have hereunto set
my hand and seal, this Twenty-seventh day of April, in the
year of our Lord One thousand eight hundred and seventy-