Improvements in Friction Clutches or Power Transmitters.
Year: 1893

page_text: Date of Application, 10th Feb., 1893
Complete Specification Left, 9th Nov., 1893-Accepted, 9th Dec., 1893
PROVISIONAL SPECIFICATION.
Improvements in Friction Clutches or Power Transmitters.
I, WILLIAM HENRY LINDSAY of The Shaw Engineering Works, Ashton
Gate, Bristol, Manager, do hereby declare the nature of this invention to be as
follows:-
According to this invention I construct in the following manner a friction clutch
for locking a shaft to a wheel or boss which is capable of turning freely around it
or acting as fast and loose coupling to ends of shafts.
On the shaft I secure a short cylinder. The wheel I place upon the shaft close
up to one end of this cylinder and a loose disc against the other end of the cylinder.
Around the cylinder I place a cylindrical coil formed from a bar of spring metal.
One end of the coil I secure to the wheel and the other to the disc. On the
opposite side of the disc I also provide a small friction clutch for locking the disc
to the shaft.
When the wheel is to be clutched to the shaft the disc is locked to the shaft by
the small friction clutch and then if there is any resistance to the wheel turning
with it the spring coil becomes wound up the number of turns in it being increased
and its diameter decreased so that it firmly grasps the exterior of the cylinder or
boss which is fast on the shaft. In this way the wheel and shaft gradually become
locked together so that there is no shock on first starting the wheel or shaft into
motion.
When the small friction clutch is again disengaged the coiled spring expands and
is then entirely out of contact with the cylinder or boss on the shaft so that no
friction or wear takes place between them.
The small friction clutch I preferably form of a sleeve which can be slidden
end wise of the shaft but not turned around it and which is made conical on the
exterior to enter and engage with a correspondingly coned recess in the disc.
Preferably also I carry the disc and the sliding sleeve of the small friction
clutch upon a tube which fits around the shaft and stands out from one end of the
cylinder or boss which is fast upon it.
L
1000
COMPLETE SPECIFICATION.
Improvements in Friction Clutches or Power Transmitters.
I, WILLIAM HENRY LINDSAY, of The Shaw Engineering Works, Ashton
Gate, Bristol, 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 :—
According to this invention I construct in the following manner a friction clutch
for locking a shaft to a wheel or boss-which is capable of turning freely around it
or acting as fast and loose coupling to ends of shafts.
On the shaft I secure a short cylinder. The wheel I place upon the shaft close
up to one end of this cylinder and a loose disc against the other end of the cylinder.
Around the cylinder I place a cylindrical coil formed from a bar of spring metal.
One end of the coil I secure to the wheel and the other to the disc. On the
opposite side of the disc I also provide a small friction clutch for locking the disc
to the shaft.
When the wheel is to be clutched to the shaft the disc is locked to the shaft by

page_text: the small friction clutch and then if there is any resistance to the wheel turning
with it the spring coil becomes wound up the number of turns in it being increased
and its diameter decreased so that it firmly grasps the exterior of the cylinder or
boss which is fast on the shaft. In this way the wheel and shaft gradually become
locked together so that there is no shock on first starting the wheel or shaft into
motion.
When the small friction clutch is again disengaged the coiled spring expands
and is then entirely out of contact with the cylinder or boss on the shaft so that
no friction or wear takes place between them.
In the drawings annexed I have shewn the friction clutch acting as a fast and
loose coupling to the ends of two shafts.
Figure 1 is a side elevation with the upper half in section of the clutch.
Figures 2, 3 and 4 are cross sections of the same.
A is a revolving shaft and B a shaft to be made fast or loose with it. The
shaft B has fast with it a cylindrical or it might be slightly conical boss B'. C is
a coil made from a bar of spring metal surrounding the boss B' but normally out
of contact with it. Its thicker end is secured as shewn in Figure 4, to a disc on
the end of a boss A' which is keyed to a shaft A but can turn loosely around the
shaft B its thinner end is secured to a disc D which can turn freely around the
shaft B-D is a spring interposed as shown clearly in Figures 1 and 2 between
the thin end of the spring coil and the disc to prevent shock at starting. E is a
collar which can be slidden along the shaft B but cannot turn around it.
The small friction clutch used for locking the disc D to the shaft B I have
shewn in the drawings to be formed of a dished disc E¹ slit radially as shewn in
Figure 3 fixed to a collar E which can be slidden endwise along the shaft but
cannot turn around-any other suitable form of clutch might however be used in
place of this construction. The collar may be slidden end wise of the shaft by
any suitable mechanism-preferably I form a groove around the collar for a
projection F from a screw rod F to enter. The screw rod screws into a nut G
which can be revolved in either direction by a pinion G¹ upon it gearing into a
pinion H on which is a wheel H¹ of larger diameter over which passes an endless
rope or chain H2. The bearings of the pinions G' and H are carried by an arm I
which projects downwards from a collar I which fits loosely around the shaft B
but which is as the drawings shew prevented from moving endwise along it. By
pulling the cord or chain downwards on one or other side of the wheel H¹ the
collar E will be moved in one or other direction along the shaft B. When the
collar E is moved towards the disc D and the outer edge of the disc E' is thereby
brought against the side of this disc all further movement of the collar then tends
to flatten the disc E¹ and cause its circumference to bear very forcibly against the
inner circumference of a cylindrical rim D which stands out from the side of the
disc D. When this takes place the disc D is securely lock to the collar and so to
the shaft B and if the shaft A is revolving the spring coil will be further wound,
that is, the number of coils in it will be somewhat increased and it will then grip
the solid boss B' and the two shafts will revolve together.
When the shafts are to be disengaged from one another the collar E is moved
away from the disc D and when the disc E' no longer bears against this wheel the
spring coil again expands and releases its hold of the boss B'.
If the clutch were to be used for coupling a driving wheel to a shaft, a driving
wheel capable of turning freely around the shaft B would be substituted for the
disc on the boss A¹.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is
1. A friction clutch composed of a coiled bar of spring metal surrounding a boss
fixed on a shaft and secured at its two ends to two discs close up to the ends of
the boss and free to turn loosely on the shaft and of a light friction clutch for

page_text: making one disc fast with the shaft whenever desired so that if the other disc is
revolving and the shaft at rest or the shaft is revolving and the disc at rest the
spring coil becomes further coiled and grips the boss thereby locking all the parts
securely together.
2. The construction of friction clutches substantially as herein before described
and illustrated in the drawing annexed.
n
1000
W. H. LINDSAY.