IMPROVEMENTS IN FRICTION CLUTCHES AND IN CONNECTED MECHANISM CONSTITUTING SHAFT COUPLINGS AND SAFETY ATTACHMENTS FOR ELEVATORS.
Year: 1882

page_text: LETTERS PATENT to Dennis Frisbie, Mechanical Engineer, of New Haven, in
the County of New Haven and State of Connecticut, one of the United States
of America, for an Invention of IMPROVEMENTS IN FRICTION CLUTCHES AND
IN CONNECTED MECHANISM CONSTITUTING SHAFT COUPLINGS AND SAFETY
ATTACHMENTS FOR ELEVATORS.
PROVISIONAL SPECIFICATION left by the said Dennis Frisbie at the
Office of the Commissioners of Patents on the 17th October 1882.
DENNIS FRISBIE, Mechanical Engineer, of New Haven, in the County of New.
Haven and State of Connecticut, one of the United States of America, "IMPROVE-
MENTS IN FRICTION CLUTCHES AND IN CONNECTED MECHANISM CONSTITUTING
SHAFT COUPLINGS AND SAFETY ATTACHMENTS FOR ELEVATORS."
My present improvement in Friction Clutches is based on the invention set forth
in the U.S. Patent to A. B. Bean, dated March 3rd, 1874, No. 148,165.
I so construct the parts that the bearing-pieces or friction blocks which are
connected with one wheel, and traverse around in an annular groove in the other
wheel when the clutch is disengaged, induce the required friction when the clutch
is engaged, by acting on inclined surfaces. The bearing-pieces which are thus
traversed are V-shaped, and move in a corresponding reversed V-shaped groove or
dove-tailed groove. The frictional surfaces are formed with blocks of wood firmly:
supported in metal.
I dispense with the cone as a means of communicating force to the clutch-levers
to engage the clutch, and substitute a sleeve adapted to similarly slide on the shaft,
and connect the sleeve with the ends of the clutch-levers by links arrranged to
serve as toggle levers when the sleeve is moved. I provide for adjusting the train
of connections from each clutch lever to its corresponding bearing piece so that
all will bear and let go equally, and so that the bearing-pieces will act with any
required force when the links or toggle levers are in their most advantageous
position. This is effected by means of screw-nuts peculiarly constructed, and

page_text: provided each with a pinching screw, by which a strong pressure can be induced
on a properly threaded shoe bearing against the side of the corresponding bolt.
By this means, a strong pinch is effected to hold the nut very reliably in placo
when the proper adjustment is attained, without disturbing the adjustment in
doing so..
When the clutch is applied to connect two lengths of shafting, I hold the two
lengths efficiently in line at the center by an elongated hub on one of the
wheels, with a provision by means of an exchangeable bushing for allowing
for wear.
I employ one or more guide-bolts or guide-pins in the several radial levers
which communicate the motion from the clutch levers to the friction blocks. They
allow the slight amount of motion required in these lovers, and serve to maintain
each lever reliably in position.
Springs mounted around these guide-bolts, and abutting under heads or nuts
thereon, take up the lost motion, and induce a force tending to keep the clutch.
disengaged.
When the clutch is applied in this manner, to connect two shafts in line, its
function corresponds to what is generally known as a shaft-coupling, and it may
bo so denominated. When it is used in other situations, the long hub and
removeable bearing are not necessary; but in other respects the construction is the
samo.
The V-shape of tho friction-blocks, and the corresponding dove-tail shape of the
groove in which they run, allow the presentation of a largor friction surface, and a
correspondingly increased efficiency with a given amount of strain on the clutch-
levers and thie connecting mechanism.
The substitution of the links for the cone blocks shown in the said Bean patent,
as a means of operating the clutch-levers, is of advantage in several important
respects, eminently in the reduction. of frictional resistance between these parts
in engaging and disengaging the clutch. By a proper adjustment of the links, the
engaging or tightening movement of the bearing pieces or friction blocks is rapid
in the first part of the engaging movement, when the resistance is inappreciable,
and the purchase or mechanical advantage in communicating the motion is greater
afterwards when the friction blocks have been brought firmly to their bearings, so
that the resistance is greatest,
When the clutch is applied in combination with other parts, to constitute a
safety attachment for passenger elevators in buildings, the links may be dispensed
with. The clutch-levers are weighted, but in other respects the clutch may be, the
same.
I mount in the elevator carriage a transverse shaft, having a pinion on each.end
engaging in fixed racks oxtending up and down a stout framing at the side of the
hoist-way. This shaft consequently is compelled to revolve in one direction and the
other, as the elevator is raisod and depressed.
The shaft carries a loose wheel having a strong stop or arm, so arranged that
the partial turning of this loose wheel brings it in contact with a strong stop or
arm on the elevator carriage. I cushion one or both these arms with wool, rubber,
or analogous elastic material, and arrange for connecting the loose wheel to the
shaft by the friction clutch, so that it shall make a partial revolution with the
shaft when thus connected, and shall, by the contact of its stop with the stop on
the carriage, arrest the motion.
Under ordinary conditions, the loose wheel is unclutched, and the shaft and
clutch mechanism is allowed to turn idly. Whenever by any derangement or
breakage the carriage falls, or tends to fall, the engagement of its pinions with the
fixed racks induces an unusually rapid revolution of the shaft. The clutch levers
are weighted, so as to be strongly affected by centrifugal force, and are held in ward
by strong but exactly adjustable springs. The adjustment should be such that the
highest allowable rate of motion of the elevator carriage will produce no effect on
the clutch, but that a slight increase in the velocity above that rate, will in
induce

page_text: the levers to fly outward, and engage the clutch with the loose wheel. This
compels the latter to perform a partial revolution, and brings its arm in contact
with the arm on the carriage, and through the elastic cushion provided, arrests the
motion of itself, and of the clutch and shaft, and by the réliable engagement of
the pinions with the fixed racks at the sides of the hoist-way, holds the carriage
suspended.
The partial rotation of the loose wheel, prior to its being stopped, operates
means for holding the clutch engaged after the motion has ceased. It will be seen
that the levers of the clutch are liable, in consequence of the absence of the
centrifugal force, to be again immediately drawn inward by their springs. This I
prevent as follows:-
A strap or rod is secured to the loose wheel, and connects indirectly to the
horizontal arm of a bell-crank lever, the upright arm of which is forked, and
engages a sleeve sliding axially on the shaft. Whenever the velocity of the descent
of the elevator carriage becomes excessive, and the clutch is engaged by the
spreading apart of the clutch levers, the partial turning of the loose wheel, by its
tension on the said strap or rod turns an equal-armed lever mounted below, and by
a connection from the opposite end of this lever to the bell-crank lever, turns the
latter, and throws the sleeve into the space between the extended clutch levers,
and holds them apart. The sleeve has no tendency to retreat when the motion
ceases. It holds everything stationary until the accident can be repaired.
In practice, I employ also a strap wound partially around the loose wheel so as
to work in the opposite direction. This is of service in restoring the parts to their
original position after the accident has been repaired by providing new hoisting
ropes, or otherwise. The hoisting of the carriage causes the pinions to turn the
shaft and the attached loose wheel in the opposite direction to that which engaged
the clutch, and by the tension of the reverse strap restores the levers and the
sleeve to their original positions, and causes them to be again of no effect, but
ready, as before, to serve in case of accident.
A weight on the said rod tends to turn the loose wheel a little backward so
soon as it is free. A stop is introduced to prevent the loose wheel from turning
too far away from the stop on the carriage. Two or three inches of turning motion
is sufficient.
A spring is introduced in the connection to allow for inequalities in the tension
on the two straps in different positions of the parts, and to compensate for changes
in the angular positions of the rods etc; and for defects in the workmanship, or in
the adjustment.
As a modification of this safety mechanism, I propose to employ, instead of the
straps, a cam-groove in the loose wheel receiving a roller on the bell-crank lever,
and throwing the cone or sleeve by the same slight turning motion. For some
situations, this may be preferable to the straps, because by prolonging the
cam-groove concentric to the center, I can allow for an indefinite turning of the
loose wheel before meeting the stop. A sufficient motion having been induced in
the bell-crauk lever to set the friction clutch tightly, the loose wheel with the
cam-groove proposed may turn little or much more without mischief.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Dennis Frisbie in the Great Seal Patent Office on the
17th April 1883.
DENNIS FRISBIE, of New Haven, in the County of New Haven and State of
Connecticut, one of the United States of America, temporarily residing in
Philadelphia, County of Philadelphia, and State of Pennsylvania, one of the United
States of America "IMPROVEMENTS IN FRICTION CLUTCHES AND IN CONNECTED
MECHANISM CONSTITUTING SHAFT COUPLINGS AND SAFETY ATTACHMENTS FOR
ELEVATORS
"
My present improvement in Friction Clutches is based on the invention set forth
in tlie U.S. Patent to.A. B. Bean, dated March 3rd, 1874, No. 148,165.
I so construct the parts that the bearing-pieces or friction blocks which are
connected with one wheel and traverse around in an annular groove in the other
wheel, when the clutch is disengaged, induce the required friction when the clutch
is engaged, by acting on inclined surfaces. The bearing-pieces which are thus
traversed are V-shaped; and move in a corresponding reversed V-shaped groove or
dove-tailed groove. The frictional surfaces are formed with blocks of wood firmly
supported in metal.
1 dispense with the cone as a means of communicating force to the clutch levers
to engage the clutch, and substitute a sleeve adapted to similarly slide on the shaft,
and connect the sleeve with the ends of the clutch levers by links arranged to
serve as toggle levers when the sleeve is moved. I provide for adjusting the train
of connections from each clutch lever to its corresponding bearing-piece so that all
will bear and let go equally, and so that the bearing-pieces will act with any
required force when the links or toggle-levers are in their most advantageous
position. This is effected by means of screw-nuts peculiarly constructed, and
provided each with a pinching-screw, by which a strong pressure can bo induced
on a properly threaded shoe bearing against the side of the corresponding bolt. By
this means a strong pinch is effected to hold the nut very reliably in place when
the proper adjustment is attained, without disturbing the adjustment in doing so.
When the clutch is applied to connect two lengths of shafting, I hold the two
lengths efficiently in line at the center, by an elongated hub on one of the wheels
with a provision by means of an exchangeable bushing for allowing for wear...
I employ one or more guide-bolts or guide-pins in the several radial lovers which
communicate the motion from the clutch levers to the friction blocks. They allow
the slight amount of motion required in these levers, and serve to maintain each
lever reliably in position..
Springs mounted around these guide-bolts, and abutting under heads or nuts
thereon, take up the lost motion, and induce a force tending to keep the clutch
disengaged.
When the clutch is applied in this manner to connect two shafts in line, its
function corresponds to what is generally known as a shaft-coupling, and it may be
so denominated. When it is used in other situations, the long hub and removable
bearing are not necessary, but in other respects the construction is the same.
The V-shape of the friction blocks, and the corresponding dove-tail shape of the
groove in which they run, allow the presentation of a larger friction surface, and
a correspondingly increased efficiency with a given amount of strain on the clutch
levers and the connecting mechanism.
The substitution of the links for the cone blocks shown in the said Bean patent
as a means of operating the clutch levers is of advantage in several important
respects, eminently in the reduction of frictional resistance between these parts in
engaging and disengaging the clutch. By a proper adjustment of the links, the
engaging or tightening movement of the bearing-pieces or friction blocks is rapid

page_text: in the first part of the engaging movement, when the resistance is inappreciable,
and the purchase or mechanical advantage in communicating the motion is greater
afterwards when the friction blocks have been brought firmly to their bearings, 80
that the resistance is greatest.
When the clutch is applied in combination with other parts to constitute a safety
attachment for passenger elevators in buildings, the links may be dispensed with.
The clutch levers are weighted, but in other respects the clutch may be the same.
I mount in the elevator carriage a transverse shaft having a pinion on each end
engaging in fixed racks extending up and down a stout framing at the side of the
hoist-way. This shaft consequently is compelled to revolve in one direction and
the other as the elevator is raised and depressed.
The shaft carries a loose wheel having a strong stop or arm so arranged that the
partial turning of this loose wheel brings it in contact with a strong stop or arm
on the elevator carriage. I cushion one or both these arms with wool, rubber, or
analogous elastic material, and arrange for connecting the loose wheel to the shaft
by the friction clutch, so that it shall make a partial revolution with the shaft
when thus connected, and shall by the contact of its stop with the stop on the
carriage arrest the motion.
Under ordinary conditions the loose wheel is un-clutched, and the shaft and
clutch mechanism is allowed to turn idly. Whenever by any derangement or
breakage the carriage falls, or tends to fall, the engagement of its pinions with the
fixed racks induces an unusually rapid revolution of the shaft. The clutch levers
are weighted, so as to be strongly affected by centrifugal force, and are held inward
by strong but exactly adjustable springs. The adjustment should be such that the
highest allowable rate of motion of the elevator carriage will produce no effect on
the clutch, but that a slight increase in the velocity above that rate will induce
the levers to fly outward and engage the clutch with the loose wheel. This
compels the latter to perform a partial revolution, and brings its arm in contact
with the arm on the carriage, and through the elastic cushion provided, arrests the
motion of itself, and of the clutch and shaft, and by the reliable engagement of the
pinions with the fixed racks at the sides of the hoist-way holds the carriage
suspended.
'
The partial rotation of the loose wheel, prior to its being stopped, operates means
for holding the clutch engaged after the motion has ceased. It will be seen that
the levers of the clutch are liable, in consequence of the absence of the centrifugal
force, to be again immediately drawn inward by their springs. This I prevent as
follows:-
A strap or rod is secured to the loose wheel, and connects indirectly to the
horizontal arm of a bell-crank lever, the upright arm of which is forked, and
engages a sleeve sliding axially on the shaft.. Whenever the velocity of the descent
of the elevator carriage becomes excessive, and the clutch is engaged by the
spreading apart of the clutch levers, the partial turning of the loose wheel, by its
tension on the said strap or rod, turns an equal-armed lever mounted below, and
by a connection from the opposite end of this lever to the bell-crank lever, turns
the latter, and throws the sleeve into the space between the extended clutch-levers,
and holds them apart. The sleeve has no tendency to retreat when the motion
ceases. It holds everything stationary until the accident can be repaired.
In practice, I employ also a reverse strap wound partially around the loose wheel
so as to work in the opposite direction. This is of service in restoring the parts to
their original position after the accident has been repaired, by providing new
hoisting ropes, or otherwise. The hoisting of the carriage causes the pinions to
turn the shaft and the attached loose wheel in the opposite direction to that which
engaged the clutch, and by the tension of the reverse strap restores the levers and
the sleeve to their original positions, and causes them to be again of no effect, but
ready, as before, to serve in case of accident.
A weight on the said rod tends to turn the loose wheel a little backward so soon
as it is free.

page_text: A stop is introduced to prevent the loose wheel from turning too far away from
the stop on the carriage. Two or three inches of turning motion is sufficient.
A spring is introduced in the connection to allow for inequalities in the tension
on the two straps in different positions of the parts, and to compensate for changes
in the angular positions of the rods, etc., and for defects in the workmanship, or in
the adjustment.
As a modification of this safety mechanism, I propose to employ, instead of the
straps, a cam groove in the loose wheel receiving a roller on the bell-crank lever,
and throwing the cone or sleeve by the same slight turning motion. For some
situations, this may be preferable to the straps, because by prolonging the cam
groove concentric to the center, I can allow for an indefinite turning of tlie loose
wheel before meeting the stop. A sufficient notion having been induced in the
bell-crank lever to set the friction clutch tightly, the loose wheel with the cam
groove proposed may turn little or much more without mischief.
The accompanying drawings form a part of this specification, and represent what
I consider the best means of carrying out the invention.
Figure 1 is a central longitudinal section through my clutch, showing it used to
connect or dis-connect two shafts in line.
Figs. 2, 3 and 4 are enlarged views of details thereof.
Fig. 2 represents my peculiar means for locking the adjustable nut on the bolt.
It is shown as viewed in the line of the bolt.
Fig. 3 is a section in the plane of the axis of the bolt.
Fig. 4 is a separate part thereof, which I term the "shoe."
The remaining figures show the clutch applied to constitute a safety attachment
for an elevator.
Fig. 5 is a side elevation showing the entire elevator carriage, and the adjacent
parts on a small scale.
Figa 6 and 7 show the novel parts thereof on a larger scale. They are elevations
taken at right angles to each other, certain portions in Fig. 6 being broken away
to better show the parts beyond.
Figs. 8 and 9 show a modification.
Fig. 8 is a side elevation, and
Fig. 9 a cross section.
The drawings represent the novel parts, with so much of the ordinary parts as is
necessary to indicate their relations thereto.
Similar letters of reference indicate like parts in all the figures.
Referring to Figs. 1, 2, 3 and 4, A and B are adjacent ends of two adjacent
lengths in a line of shafting, which it is the object of my invention. to connect
firmly together, or to disconnect, and to rotate the one independently of the other,
as may be desired from time to time. A is a stout hub or boss secured on the
part A by a feather.
The part. A extends out beyond the end of the shaft A, and loosely encloses the
adjacent end of the shaft B. C is a removable bushing which fills a space between
the shaft B'and the inner surface of A.
Ais a stout and wide flange extending out from the hub A, and forming a
wheel. A and A% are annular, conical ribs, lips or flanges, cast a little distance
apart on the face which is presented towards the other shaft B. The annular space
between is of dove-tailed section, and smoothly turned and finished. The outer
edge of each is broad, and finished plane.
D is a stout wheel rigidly secured on the shaft B by a key q
E, E, are clutch levers of bell-crank form, fulcrumed in the wheel D at the
points represented. The long arm of each lies approximately parallel to the
shaft B.
To the outer end of each lever E is knuckled a link F, the other end of which is
knuckled to a sleeve G, which is traversed longitudinally on the shaft B, by means
of a lever not shown, engaging in the groove in the manner commonly practiced in
operating friction clutches.
..

page_text: One arm of each of the levers E extends radially inward, and engages with the
inner end of a corresponding radial lever H carried on the wheel D. As the
sleeve G is moved end-wise on the shaft A, the levers E are turned by the links F,
and the short radial arm of each lever E acts on its lever H, and turns it slightly
on its axis or knife-edge h, which is near the periphery of the wheel D. One or
more guide-bolts D₁ fixed in the wheel D are equipped with spiral springs D²,
abutting under the heads of the bolts D, and holding the levers H in their bearings.
They take up all the slack or lost motion of the parts.
I, I, are dove-tailed friction pieces or friction blocks fitted in the dove-tailed space
between the lips A, A. A smoothly finished bolt I' leads from each through a
close-fitting hole in the wheel D, and through a loose-fitting hole in the lever H.
Its outer end is equipped with a peculiarly formed, nut which engages it with the
lever H, with capacity for nice and very reliable adjustment. The main portion J
of this nut is adjusted in the ordinary manner by turning more or less in one
direction or the other. When the desired point is found, it is set firmly in position
in the bolt by turning a pinching-screw K, the point of which enters a little into a
long shoe K! fitted in a recess in the nut, as indicated, and threaded to match the
threads in the bolt. To adjust the grip, the screw K should be slackened, and the
nut J turned to the required extent, and then the screw K tightened again.
The shoe is formed. with a broad flange which finds a fair bearing on the outer
face of the main body of the nut. The strain is communicated to the bolt I
mainly through the main body of the nut. The threads on the shoe. K allow it
to press strongly on the bolt without injuring the screw-threads. The construction
is strong and reliable.
-Pieces of lignum-vitae or other suitable wood, i, are fitted in the working faces
of the V-shaped bearing blocks I, so as to give the working friction against the
beveled inner faces of the flanges A4, A. Pieces of wood d are correspondingly
fitted in recesses in the wheel D so as to give the working friction against the
plane edges of the lips A, A. The wood is preferably mounted with the end of
the grain presented to receive the wear, and it is important to saturate it with oil
before the device is put to work.
In the application of the clutch to a safety attachment for an elevator, the
provisions for holding two separate lengths of shafts in line are not required.
The safety attachment may be applied to either passenger or freight elevators,
traversing in the ordinary manner up and down, operated by ropes. I carry on
the elevator carriage a strong transverse shaft, having a pinion on each end
engaging in corresponding racks extending up and down on the fixed guide-way.
Under ordinary conditions; this shaft revolves idly in one direction and the other,
as the elevator is raised and depressed.
I mount on this shaft a loose wheel having a strong stop or arm arranged to
meet a strong stop or arm on the elevator carriage so that it cannot turn. I
provide means for grasping this loose wheel by the friction clutch, in case the
elevator carriage moves too fast. For this purpose, the levers of the clutch are
weighted so as to be sufficiently affected by centrifugal force, and are held inward
by sufficiently strong springs, adjusted so that the rotation of the shaft at the
ordinary speed shall have no effect.
When the elevator ropes break, or any derangement occurs which allows the
elevator carriage to fall, the falling movement will by the action of the pinions in the
racks rotate the shaft with increased rapidity. So soon as the speed exceeds that
where the centrifugal force on the loaded arms of the clutch overcomes the resistance
of the nicely adjusted springs, the clutch levers fly outward and engage the clutch,
and the descent of the carriage is instantly and reliably arrested. This is due to
the fact that the pinions on the shaft engage with the fixed, rack on the framing,
the clutch engages the loose wheel to the shaft, and the contact to the arm on the
loose wheel with the arm on the carriage prevents the loose wheel from revolving.
So far as yet described, the device would be of great utility in checking a sudden

page_text: .
fall of the carriage; but without some further provision, the arresting of the motion
would, by extinguishing the centrifugal force, and allowing the arms of the friction
clutch to be again drawn together by their springs, disengage the clutch, and allow
the shaft to revolve again. The elevator carriage would, therefore, commence to
descend, and would continue to do so until it again acquired a sufficiently high
velocity to again throw out the weighted arms by the centrifugal force, and again
engage the clutch. This action would continue intermittently, or perhaps with an
approximately uniform motion until the carriage had reached the bottom.
I can use the invention with some advantage thus conditioned; but I have
provided a further device by which a partial turning of the loose wheel is allowed
before its arm meets the fixed stop, and such turning is made to effect an axial
movement of a cone or sleeve on the shaft, which sleeve thrusts itself between the
extended arms of the clutch levers, and holds them extended, and consequently
bolds the clutch engaged after all motion is stopped.
Referring to Figs. 5 to 7 inclusive, Lis the fixed framework, and I are racks of
iron or steel strongly bolted, or otherwise secured thereon. M is the elevator car
or carriage, guided by the frame-work L in any ordinary or suitable manner.
N, N, are the hoisting ropes, operated in any ordinary or suitable manner, to raise
and lower the carriage M as required. Under all ordinary conditions, my safety
apparatus will be of no effect.
O is a transverse shaft, supported in bearings in the carriage M, and carried up
and down therewith, and provided at each end with a pinion O' engaged in the
corresponding rack 4. The shaft O carries thereon a friction clutch, the levers T
of which are weighted, as indicated by T'.
-
The construction of this clutch may be in all respects like that shown in
Figs. 1, 2, 3 and 4 except that the clutch-levers are weighted. The levers T corre-
spond in their general arrangement and functions to the clutch-levers E of Fig. 1 ;
but instead of operating the levers T of this clutch primarily by moving the sleeve,
I initiate the operation by centrifugal force acting on the levers which are
weighted to give more of this effect. But. I. prefer to dispense with the links, and.
to move the sleeve entirely by other means now to be described, which move the
sleeve in the opposite direction.
Centrifugal force is relied on to throw outward these weighted clutch levers T, TI,
when the velocity is too high. Under ordinary conditions, the centrifugal force is
resisted by the tension of springs described further on..
This clutch engages, when the velocity is too high, with a wheel P of similar
size, mounted loosely on the shaft O, and provided with a strong arm or stop Pl
projecting from the face opposite to the clutch-wheel O. There is a strong arm M'
fixed on the elevator carriage M, against which this arm P' strikes through the
medium of a stout cushion M of india rubber, or other suitable material. When
the loose wheel P is thus held, it is absolutely stationary in the carriage M, as if
it were a permanently fixed portion thereof, and the clutching of the revolving
shaft thereto arrests the revolving shaft, and holds it absolutely immovable.
But when, the clutch is disengaged, and the elevator is being raised and lowered
by its ropes in the ordinary manner, the wheel P does not stand with its stop P¹
in contact with the fixed cushion M. The wheel P is by the gravity of the
stop P, and of an additional attachment for the purpose, turned a little backward
so as to hold its stop P' a little way from the fixed stop. This allows a partial
turning of the loose wheel P when an accident occurs, and the clutch is engaged.
This partial turning is caused to perform the important function of locking the
clutch in the clutched position.
This locking of the parts in the clutched position is effected by the sleeve U
which is free to move end wise on the shaft O, and is controlled by the forked
upright arm of a bell-crank lever V, which is pivoted to the carriage M, at the
point . The lower arm engages indirectly with the wheel P, by means of a
strap R, which traverses partially around a guide pulley, and is attached to the
proper point in the periphery of the wheel P by means of a bolt m'.

page_text: A corresponding strap or rod of metal R2, is attached to another point m² on the
wheel P. This connects to a lever W, which turns on a pivot carried on the
carriage M. The opposite end of the lever W is connected by a spring R³ and rod R*
to the lever V as shown.
If the ropes N break and allow the carriage M to fall, or if through any other
derangement the carriage descends faster than the proper speed, the arms T, T
will be thrown outward by centrifugal force in opposition to the tension of the
springs Q, and the clutch-wheel 02 will engage with the wheel P and compel it to
turn. So soon as it has turned sufficiently to bring its stop P' against the arm M
its further turning will be arrested, and the pinions O₁ being thus prevented from
revolving, will prevent the further descent of the carriage.
Q' and Q are respectively nuts and jam-nuts which control the tension of the
springs Q. These springs tend to draw the loaded ends of the levers T together,
and to keep the clutch out of engagement with the wheel P. By adjusting the
nuts Q and jam-nuts Q, the tension of these springs may be adjusted with great
delicacy. They should be set so that the levers T will be held inward or together
by a force only a little in excess of the centrifugal force when the car is running
at its ordinary. full speed. A little more rapid motion of the car in either direction
would cause the centrifugal force of the weights T to overcome the tension of the
springs Q, and to engage the clutch. This is only liable to occur during the descent
of the carriage, and in consequence of some breakage or derangement.
It is possible by engaging the friction clutch less forcibly to simply retard
without arresting the revolution of the gear-wheels 01, and thus to allow the
carriage to descend slowly: The force with which the clutch O2 will engage with
the wheel P, and thus the force with which the descent of the carriage will be
retarded, will depend on the centrifugal force felt by the arms T. Whenever under
the condition so far explained, the carriage slackens its motion so as to nearly, or
quite extinguish that force, the springs will draw inward the weighted arms T¹,
and the clutch will relax so as to allow an increase of motion. When the velocity
becomes too high, the centrifugal force throwing out the loaded levers T, T¹, will
increase the friction, and by engaging O strongly with P retards or arrests the
motion.
The apparatus may be operated in this manner, if preferred, in which case the
carriage will descend with moderate speed to the bottom. For most situations,
however, I prefer to employ the addition now to be described, and which insures an
immediate locking of the levers T, T', in the extended position, and the firm
clutching of the parts O and P together. This insures a rigidly stationary condition
of the carriage until the proper repairs have been effected, and the machine is ready
to be again worked in the ordinary manner. But with my provisions for a partial
turning of the loose wheel P, and with my strap R³, and bell-crank lever applied as
shown, it follows that when an accident occurs, and the carriage commences to fall,
the instant the shaft O acquires an improperly high velocity, the loaded levers T, T¹,
are thrown outward by the centrifugal force, and the effect of the engagement with
the wheel P, and the turning of the latter therewith, is not only to bring its arm Pl
into strong contact with the cushion M* on the arm M', and stop the gear-wheel O'
but also to change the position of the straps R', R². It slackens the strap R' and
tightens the strap R2. This rocks the lever W on its center w, and through the
tension of the spring R³ pulls downward the horizontal arm of the lever V, with
the effect to turn that lever partially around on its center v, and to move the cone
or sleeve U towards the clutch wheel 0%. This movement thrusts the sleeve U
between the loaded ends of the levers T, and leaves it there where it holds them
reliably apart, and the clutch consequently engaged firmly for any period desired
after the falling motion of the carriage is arrested.
:
When new hoisting ropes N have been applied, or other proper repairs have been
made, and the machine is ready to start, the parts may be restored to their original.
condition, by simply hoisting on the ropes N, so as to induce the proper reverse
motion of the wheel P and its connections. Or, the attendant may temporarily

page_text: remove the center v, thus setting the lever V and the sleeve U at liberty, when the
proper changes may be made by hand. So soon as, by any means the sleeve U
has been moved out sufficiently far, the clutch levers T, T, are drawn together by
the springs Q, and the clutch 02, with its connected shaft O and gear-wheels O',. is
disengaged from the wheel P, all is again ready for working. Thus conditioned,
the wheel P partially rotates backward, so as to bring the arm P¹ to a proper
distance away from the arm M, and all is again in the same condition as before,
I limit the extent of the backward turning of, the loose wheel P by a stop P,
preferably of some elastic material, fixed on the carriage M, in a position to receive
the stop or arm M-in its backward motion. Under ordinary circumstances, it is
amply sufficient to allow one-twentieth (/) of a revolution to the loose wheel P..
A strong casting M³ is fitted on the carriage M, adjacent to the shaft O. It is
of such form as to stand on the side of the upright L, opposite to the 'rack 1, and
holds the parts reliably in position to guard against the pinions O' ever by any
strain, springing or slipping out of engagement with the racks l.
This elevator attachment insures the arresting of the falling motion of the
carriage gradually and gently instead of abruptly and violently. The softness of
the arrest is due not so much to the cushion M, between the stops M' and P' as
to the gentle action of the clutch 0°. Its engagement with the wheel P is gradual,
and allows a sliding of the parts one upon the other, so as to relieve the machinery
from concussion.
The carriage is always arrested with the stops P, M', in contact. If the friction
clutch is so adjusted that the levers T, T', will move apart to a greater or less
extent, the cone U, and consequently the bell-crank lever V, are liable to be arrested
in various positions. The spring R³ allows for any discrepancy in these motions.
Modifications may be made in many of the details. Some parts of the invention
may be used without the others.
In the modification shown in Figs. 8 and 9, a portion of a face cam is mounted
on the loose wheel P; and receives a roller on the extremity of the horizontal arm
of the bell-crank lever V. When in consequence of an accident the loose wheel P
is clutched, and commences to turn, the face cam by its form first turns the lever V,
and shifts the cone or sleeve U, and then stands stationary, allowing the loose
wheel P to perform any further small portion of a revolution which is required to
compress the cushion M, and bring the parts to rest without subjecting the
lever V or the sleeve U to any further motion. This form has some advantages
over any of the others shown. It allows the cone or sleeve U to be set with
certainty in the position to fully secure the clutch, with only a portion of the
movement of the wheel P; and it allows the wheel to come to rest indifferently in
a variety of positions, without subjecting those parts to any further strain.
In this modification, the lower arm of the lever V is obviously subjected to a
considerable side strain. I provide for resisting this by embracing it in a U-shaped
yoke. I facilitate and insure the certainty of the movement on the rare occasions
when this apparatus shall be called into action by applying a roller which traverses
in the yoke, and receives all the side strain.
In this modification, the backward turning of the loose wheel P is induced by a
spring (See Fig. 9). A similar spring may obviously be applied on the form of the
safety mechanism shown in Figs. 5, 6 and 7.
There may be two, four, or various other number of these clutch levers Erand
links F; all connected to the same sleeve G, and operated thereby.
I propose to employ a considerable number of the guide-bolts D¹. Each may
have a head, and a spring D³, or these adjuncts may be employed on only one, in
which latter case the other guide-bolts would serve the function simply of loose
fitting pins to steady the lever, H in position, and allow it to have the slight
motion required. When equipped with the springs D³, they perform the further
function of pressing the respective lovers H more or less strongly towards the
wbeel D:
The boss on the wheel D around each bolt I may be increased, always taking

page_text: care to provide a corresponding and somewhat deeper recess in the adjacent portion
of the lever H. Or the boss can be omitted altogether. Its presence simply allows
a longer bearing for the bolt I¹.
1
The wood bearings & and i may be omitted, and the metal of the friction piece I
and of the wheel D respectively allowed to bear directly against the flanges A', A.
Instead of employing a loose feather C, a tight fitting key may be driven there.
A feather allows the respective wheels, and also shafts A and B, to play end-wise
to a reasonable extent, without interfering with or affecting the action of the
clutch. I esteem it preferable for this reason.
The friction roller D may be omitted, and the contact formed directly.
Although I have described the invention as applied to connect two shafts in
line, and one feature of it, the socketing of the end of one shaft in the casting is
particularly applicable thereto, it will be understood that the other parts of the
invention may be used in friction clutches in any other situation, among which are
cases where a continuous shaft extends through the apparatus, and a pulley or
gear wheel corresponding to the wheel D, and belted, geared, or otherwise
connected to other mechanism is loose on such shaft, except as it is engaged by the
friction clutch. The invention is applicable in such cases, and in all cases where
the wheel D and the clutch levers E traverse around continuously, and the pulley D
with which it engages is sometimes at rest, and also under the reverse conditions,
where the levers E and wheel D, and the connected shaft A are sometimes stationary,
and the pulley or wheel E is continuously rotating.
The sinking of the end of the screw K a little into the shoe K' is useful in
holding the parts J and K together before their application to the bolt, and is
generally of advantage, but it may be omitted, and the screw allowed to bear
simply against a plane surface of the shoe, if desired in any case.
The dove-tail or inverted V-shape of the friction blocks I, with the bearing faces
properly equipped with wood, as shown, gives a frictional surface which extends
over a greater area, and induces a greater pressure on a unit of area with a given
pull on the bolt 1 than the rectangular blocks and parallel bearing surfaces
heretofore employed. This form also centers the work truly at each operation.
Care being taken to manufacture the parts accurately, with the flanges A', A³,
exactly concentric to the shaft A and bushing C, any tendency of one part to get
out of line with the other is corrected when the clutch is engaged.
In the elevator, it is preferable for several reasons to employ two racks on the
upright framing, one on one side of the carriage, and the other on the other, and
to mount a similar gear-wheel on each end of the transverse shaft; but a single
rack and pinion may be used with tolerable safety.
In the elevator, I can operate the locking cone U with some success with an
inelastic.connection of the lever W to the lever V; but I prefer the spring R³, as
it avoids the necessity for nice adjustment of the point to which the cone U will'
be advanced when the wheel is arrested by the engagement of its stop P¹.
In place of the cushion M*, I can use a spiral or other suitable form of spring."'
Or the stops M, P', may be allowed to strike directly together.
Some of the advantages due to certain features of the invention may be
separately enumerated as follows:-
First By reason of the dove-tail or inverted V-shape of the friction blocks I,
and of the groove in which they work, I am able to obtain a greater frictional
surface, and to apply a greater force on such surface by a given pull on the bolts 1¹,
and also to aid in centering the parts by the application of the clutch.
Second: By reason of the long hub A', A2, and bushing C, I obtain a centering
independent of and additional to that formed by the frictional surfaces, which is
important in connecting lengths of shafting.
:
Third By reason of the compound lever H, E, worked by the toggle links F
and sleeve G, I obtain an extraordinary multiplication of force in inducing pressure,
at the period when the clutch is fully applied.
.
Fourth: By reason of the bolt I' and adjusting nut J thereon, I add to the last-

page_text: named combination facilities for adjusting with great nicety as the friction surfaces
become compressed or worn away.
Fifth By reason of the pinching screw K and threaded shoe K', in the nut J,
and serving on the bolt I to operate the friction piece I by the lever H, and its
connections, I secure unusual facility, nicety and certainty of adjustment.
Sixth By reason of the londed levers T, T', and gear-wheel .01, when the
mechanism is carried on an elevator carriage, and of the engagement of the said
gear-wheel with a rack on the fixed work Lat, the side of the hoistway, I am
able to operate the clutch whenever the descent of the carriage exceeds a safe
limit, and thus to reliably insure against accident from a failure of the ordinary
hoisting means.
Seventh: By reason of the springs Q, and adjusting means Q1, Q, arranged as
shown relatively to the other parts, I am able to determine with nicety the
velocity of the descent at which the clutch shall be brought into action, and arrest
the motion.
Eighth By reason of the loose wheel P, having the stop P¹, and of the cone or
sleeve U, bell-crank V and rod R, arranged as shown relatively to the other parts,
I am able, when the proper velocity is exceeded, and the friction clutch is engaged,
to hold it engaged after the motion is arrested.
Ninth By reason of the elastic cushion M*, in. combination with the other
parts, I diminish the shock when the clutch is thrown into action.
I claim as my Invention :-
1 In a friction clutch, an annular channel of dove-tail or reversed" V-shaped
section, in combination with corresponding reversed V-shaped friction pieces or
blocks traversed therein, and attached to the other part, and with abutting surfaces
or pieces to allow of inducing the friction by clamping or pressing the reversed
V-shaped blocks, and the abutting pieces or surfaces together, as herein specified.
2 The two independent lengths of shafting A, B, the long hub A1, A2, and
busliing C, in combination with each other, and with the wheels A³, D, mounted on
the respective shafts, and friction pieces I, and means for operating them, arranged
to serve as a friction clutch, with the shafts held in line at the center, as heroin
specified.
3d: In a friction clutch, the friction pieces I, carried on one wheel, and engaging
frictionally with the other, in combination with the compound lover H, E, toggle
links F and operating sleeve G, as herein specified.
4th: The bolt 1, and adjusting nut J thereon, in combination with the friction-
piece I, and with the compound lever H, E, toggle link F and sleeve G to allow of
adjustment to accommodate the toggle action, as herein specified.
5: The pinching screw K and threaded shoe K, in combination with each
other, and with the nut J, bolt I, friction-piece I, and with the lever H, and its
operating means, ns herein specified.
G: In a safety attachment for elevator, the loaded levers T, T', and friction
clutch O controlled thereby, in combination with, the shaft O and gear-wheel O',
carried on the elevator carriage, and with a rack on the fixed guide-way L,
arranged to serve as herein specified.
7th The carriage M, shaft O, and pinion or pinions 0', engaging in the rack or
racks, on the fixed frame-work, in combination with each other, and with the
friction clutch O, having levers T, T¹, arranged to be engaged by centrifugal force,
and with the springs Q, adjusting nuts Q and jam nuts Q, substantially as herein
specified.
8th. The shaft O, carrying one or more pinions O'; engaging with one or more
fixed racks, in combination with a friction clutch O, engaged by centrifugal.
force when the proper velocity is exceeded, and with the loose wheel P, having an
arm or stop P, and with the sleeve U, bell-crank V, and rod R', connected to the
said bell-crauk, all arranged to serve substantially as herein specified.
9th The combination with the shaft O, pinion O, and friction clutch 0% of the
loose wheel P, having an arm P engaging with an arm M on the carriage M,

page_text: through an elastic cushion M*, and with the rod R¹, bell-crank V, and cone or
sleeve U for holding the friction clutch engaged after the motion is arrested, and
with the weight R³ for controlling the loose wheel P while the safety mechanism is
out of action, as herein specified.
In Witness whereof, I, the said Dennis Frisbie, have hereunto set my hand
and seal this Fifth day of March, in the year of our Lord One thousand
eight hundred and eighty-three.
Witnesses:
WILLIAM GEORGE. STECKLAIR.
WILLIAM LARZELEN
DENNIS FRISBIE (L.S.).