Improvements in Friction Clutches.
Year: 1896

page_text: PROVISIONAL SPECIFICATION.
Improvements in Friction Clutches.
I NORMAN MACBETH, of Macbeth Bros. & Co., 55 Knowsley Street, Bolton, in the
County of Lancaster, Engineer, do hereby declare the nature of this invention
to be as follows:-
My said invention relates to improvements in friction clutches for use in the
transmission of rotary motion as is well understood. In a convenient form of my
improved clutch, I key or otherwise secure an internal clutch box on the shaft,
pulley or wheel to be driven or from which motion is received. In line with this
shaft I arrange another shaft carrying on its end a boss furnished with two driving
At the ends of the driving arms and carried on projections from the same,
are two friction blocks, one for each driving arm, the outer faces of the friction
blocks being curved to correspond with the internal circumference of the opposite
clutch disc. The slots or holes through which the carriers pass in the friction
blocks are large enough radially to permit of a certain amount of movement of the
blocks towards and from the turned interior of the said clutch disc. The boss
from which the driving arms project carries loosely a sleeve capable of sliding on the
boss of the driving arms or on the shaft the said sleeve being squared and slotted
to receive two saddles of suitable shape. The said saddles carry projecting studs
and the aforesaid friction blocks are also furnished with studs or their equivalents.
Side links, intended to act as toggles links extend between the studs on the saddles
and the friction blocks, each friction block being thus linked to its corresponding
saddle. The saddles are prevented from moving away from the sleeve by studs
extending from the boss and passing through the backs of the saddles or by other
suitable means. When studs are used adjustable jamb nuts on the said studs limit the
outward movement of the saddles in their slots. The end of the squared sleeve has
a circular groove to receive the cod pieces of a lever employed to shift or slide the
squared sleeve upon the shaft. Springs are interposed between the inner sides of
the saddle backs and the square sleeve the tendency of the said springs being to push
the saddles away rapidly from the centre of the shaft. The tension of the springs
can be easily regulated by set screws passing through the saddle backs and pressing
on the springs or by other suitable means. When the sliding sleeve is moved
outwards by the lever, the toggle links are thrown into an angular position and
consequently the friction blocks cease, to be pressed against the internal circum-
ference of the clutch disc and the driven shaft or part comes to rest. On the other
hand if the sliding sleeve is moved inwards the toggle links assume a straightened
position, that is a position at right. angles to the shaft, causing the blocks to be
pressed against the internal circumference of the clutch disc with the pressure due
to the adjusted tension of the springs, so that the halves of the clutch are caused
to revolve together. The use of the springs 'between the saddles and the sleeve

page_text: gives a yielding pressure or bite to the blocks which compensates for wear and
provides relief in the event of any foreign matter getting between the friction
blocks and the disc. In adjusting the clutch to proper working conditions I place
the links in position at right angles to the shaft and then by means of the set
screws adjust the springs until sufficient driving pressure or bite is put on the
blocks. When in operation the links may be thrown slightly beyond the rect-
angular or maximum thrust position so as to tend to hold the clutch in gear when
the clutch is at work.
An important feature of my invention being the interposition of the elastic or
spring media which allow the toggle links to assume a position at right angles to
the shaft between the longitudinally sliding part and the friction blocks, it must
be understood that I do not confine myself to the particular form and application
of such springs as hereinbefore set forth. The springs might for instance be
placed directly between the saddles so as to force them apart. Flat or coiled
springs might be used or rubber or other elastic bodies substituted for such
springs, or the pressure transmitting bodies such as the friction blocks might be
fitted with elastic media or springs.
In short I consider that in combination with toggle links and radially moving
friction blocks the interposition of elastic or spring arrangements or bodies between
the friction blocks and the sliding sleeve and which would permit of the toggles
coming into a position at right angles to the shaft, would be within the scope of
my invention. The arrangements for imparting pressure to the blocks might also
be varied and an external instead of an internal clutch disc might be used in
which case levers may be interposed between the toggle links and the friction
blocks.
I NORMAN MACBETHI, of Macbeth Bros. & Co., 55 Knowsley Street, Bolton, in the
County of Lancaster, Engineer, 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 and accompanying drawings:-
My said invention relates to improvements in friction clutches for use in the
transmission of rotary motion as is well understood.
To render the invention more clearly understood I will now describe the same
with the assistance of the annexed four sheets of drawings which illustrate
convenient forms of clutches constructed in accordance with my improvements.
On Sheet 1.
Fig. 1 is a face view partly in section of an improved clutch.
Fig. 2 is a sectional view at right angles to Fig. 1.
Fig. 3 is a plan view of the sliding sleeve by which the clutch is operated.
Figs. 4 and 5 are diagrams illustrating the action of the clutch.
Fig. 6 shows a modified form of the grip adjusting spring.
On Sheet 2

page_text: Figs. 7 and 8 are views of a modified form of my improved clutch.
On Sheet 3.
Figs. 9 and 10 show an additional structural modification.
On Sheet 4.
Figs. 11 and 12 show a further modification.
In constructing my improved clutch, I key or otherwise secure an internal
clutch box A on the shaft B or it might be on the pulley or wheel to be driven or
from which motion is received. In line with this shaft B I arrange the separate
driving shaft C carrying on the inner end a boss D¹ furnished with two driving
arms D, D. Carried on projections D2 from the same, are two friction blocks E È
one for each driving arm, the outer faces of the friction blocks being curved to
correspond with the internal circumference of the opposite clutch disc A.
The friction blocks E are retained on the projections De from the arms D by
confining plates D³.
The slots or holes in the friction blocks through which the carriers pass are
large enough radially, that is to say relatively to the thickness of the arms D2, to
permit of a certain amount of movement of the blocks E E towards and from the
turned interior of the said clutch dise A. The boss D from which the driving
arms D D project, carries loosely a sleeve F, capable of sliding on the boss D¹ on
the shaft C, the said sleeve F being squared and slotted as clearly shown in Figs., 1
and 3 to receive two staple shaped saddles G G. The said saddles G G carry
projecting studs G' and the aforesaid friction blocks E are also furnished with
studs E or their equivalents. Side links H intended to act as toggle links
extend between the studs G₁ of the saddles G and the studs E¹ of the friction
blocks E each opposite friction block E being thus linked to its corresponding
saddle. The blocks E are recessed to receive the pivotted ends of the links H, the
pins E passing through the links and being secured in position by the set
screws E2
The saddles are prevented from moving away from the squared
sleeve F by studs I furnished with jamb nuts I' as shown the said studs being
screwed into the sleeve and passing through the backs of the saddles. The jamb
nuts I are adjusted to the exact extent which will limit the outward movement of
the saddles in their slots. When the blocks E are pressed against the clutch
half A as in the drawings, a little clearance appears between the blocks and the
jamb nuts the blocks however lying against the nuts when the clutch is out of
gear. The cylindrical end of the squared sleeve F has a circular groove F¹ to
receive the cod-pieces of a lever employed to shift or slide the squared sleeve upon
the shaft. The said cod-pieces and lever are not shown in the drawings as any
engineer will understand their application. Springs J are interposed between the
inner sides of the saddle backs G and the square portion of the sleeve F the tendency
of the said springs being to push the saddles G away radially from the centre of
the shaft. The tension of the springs can be easily regulated by set screws K
passing through the saddle backs and pressing on the backs of the springs or by
other suitable means. The set screws are bound in their adjusted position by
jamb nuts K as shown. The ends of the springs J are forked or cut out to pass
on each side of the studs I. Instead of the said metallic spring J, I might as
shown in Fig. 6 use a block J of some elastic material such as rubber, "woodite"
or the like, the said block J being sunk in the back of the sleeve F and protected
by a cover upon which the screw K presses.
When the sliding sleeve F is moved outwards by the lever in the direction of the
arrow in full lines Fig. 2, the toggle links H are thrown into an angular position as
indicated in Fig. 5 and consequently the friction blocks E cease to be pressed
against the internal circumference of the clutch disc A and the driven shaft B or
other part comes to rest. On the other hand if the sliding sleeve F is moved
inwards in the direction of the dotted arrow Fig. 2 the toggle links H assume a
straightened position as in Fig. 4 that is a position at right angles to the shaft,
causing the blocks E to be pressed against the internal circumference of the clutch
dise A with the pressure due to the adjusted tension of the springs J so that the

page_text: dise A and shaft Bain caused to revolve. The use of the springs J between the
saddles G and the sleeve F gives a yielding pressure or bite to the blocks E which
compensates for wear and provides relief in the event of any foreign matter getting
between the friction blocks and the internal surface of the disc. In adjusting the
clutch to proper working conditions I place the links H in position at right angles
to the shaft and then by means of the set screws K and jamb nuts K adjust the
springs J until sufficient driving pressure or bite is put on the blocks E E.
When in operation the links-H may be thrown slightly beyond the rectangular
or maximum thrust position so as to tend to retain the clutch halves in frictional
contact when the clutch is at work.
ณ
Figs. 7 and 8 on Sheet 2 illustrate a further example of a modified form of clutch.
In the said figs. I will identify parts similar to corresponding parts on Sheet 1 by
similar letters. As in the previous instance the internal clutch box A is secured
to (say) the driven shaft B while on the driving shaft C I secure the boss D' with its
driving arms D.
In the present example there are four driving arms in the clutch under con-
sideration which is intended to he of a large and powerful type. For want of space
I have shown only one arm and a portion of the clutch rim.
The outer ends of the four driving arms D are connected by a flanged rim D
and opposite to the driving arms there are recesses with boundary flanges D 1 at
the sides. Into these recesses are placed the friction blocks E which are each made
in two halves E and E³.
The friction blocks are confined in the recesses by confining plates L screwed to
the flanges D D. Between the halves I place a pad J of rubber, "woodite" or
other suitable elastic or yielding substance or material the function of which
corresponds to the function of the springs J in Figs. 1 and 2. This elastic pad J
is preferably placed in a recess or pocket as shown which prevents it from spreading
or becoming displaced. The pressure from the lower half E of the friction block
is transmitted to the upper half E through the elastic pad J. The two halves are
held together by bolts K K furnished with jamb nuts and by manipulating these
bolts the compression of the elastie pad Jenn le maintained to the required extent
when the clutch is out of gear.
When the clutch is in gear a slight clearance space due to the increased com-
pression of the pad J appears between the inner jamb nuts and the lower portion E³
of the friction blocks as shown in the drawings. The lower half 1 of the friction
block is connected by toggle links H H to blocks N in the sliding sleeve F which
is loose on the driving shaft C and can be advanced and withdrawn by a clutch
lever not shown in the drawings and which carries dogs, which occupy the rear
groove F in the sleeve. A groove in the forward end of the sleeve contains the
loose blocks N, the said blocks being pivotted by the pivot studs N' to the inner
ends of the toggle links H. The blocks N simply lie foosely in the groove of the
sleeve so that it is necessary to anchor the friction blocks E to some fixed and
unyielding parts. This I do by carrying a gudgeon O on trunnions between
each pair of toggle links and connecting the said gudgeon by a tie bolt. I'
pivotted between two flanges Q projecting from the driving arms D and passing
through the gudgeon 0. There are tiro jamb nuts P and P on the tie bolt i
one on each side of the gudgeon and the nut P carries a prolongation Pus
which screws on the tie bolt and stops short of the upper jamb nut P. A set
screw passing through the side of the gudgeon screws against this prolonga-
tion P and conthines with the two jamb nuts to keep the tic holt 1 secure in its
adjusted position. By means of the jamb nuts P T on the tie holt 1', the exact
amount of frictional driving contact between the friction blocks E and the clutch
half A can be accurately adjusted.
"To prevent the possibility of faulty or careless adjustment resulting in the
bursting or breakage of the clutch half A when the clutch lever is operated to
slide the blocks E into frictional contact, I interpose a washer P of lead or other
compressible substance between the inner nut 1" and the gudgeon O so that in the

page_text: event of excessive pressure being brought to bear upon the gudgeons the lead or
other washers P2 are compressed and the excess pressure absorbed and prevented
from bursting the clutch. It will be noted that in Fig. 8 I have shown the toggle
links thrown slightly beyond the rectangular or maximum thrust position. This
I do as already explained, for the purpose of keeping the parts in frictional driving
contact. The working of the clutch will be easily understood. When in the
position shown in Fig. 8 the friction blocks E are held in driving contact with the
clutch half A so that the shaft B is driven (if such should be the arrangement).
When however the sleeve F1 is drawn out in the direction of the arrow, the toggle
links are thrown at an outward angle and the friction blocks brought away from
the clutch half A whereupon the shaft B is topped.
Figs. 9 and 10 on Sheet 3 illustrate a clutch of the same type as that shown on
Sheet 2 but with a few minor structural improvements which facilitate the working
of the clutch. The clutch half A is bolted to a coupling end B on the shaft B.
The friction blocks E are made narrower so as not to present so much frictional
surface to the clutch half A as in Figs. 7 and 8. I also furnish the inner end of
the sliding sleeve with a stop S to limit adjustably the inward traverse of the
sleeve. Apart from these and other minor characteristics the clutch shown on
Sheet 3 is similar to that already described and shown on Sheet 2.
Figs. 11 and 12 on Sheet 4 illustrate a more powerful type of clutch than that
indicated in Figs. 1 and 2.
and are
In this instance the toggle links H are connected on central vins
connected to the friction blocks E by levers X, the intervention of which gives
additional power to the toggle links H.
The levers X are jointed to the toggles H by pins XI.
A is the internal clutch box, which in this case is shown carrying a driving
pulley A¹ the clutch box being arranged to run loose on the shaft when the clutch
is out of gear: 1) are the driving arms which in this case although cast in one
are partially split as indicated at D2. The driving arms D are clipped to the
shaft by the bolts 13. If desired the driving arms may be keyed to the shaft in
the usual manner. The friction blocks E are fastened to the driving arms D by
the levers X. The pins e and b of the levers X are free to oscillate in the driving
arms D and in the friction blocks E but are rigidly fastened to the levers X by
nuts c. The friction blocks E are guided approximately by the flat surfaces d of
the arms 1 to which they are loosely held. The friction blocks E are made in
two parts E and E with interposed elastic media J such as india rubber woodite
or other resilient substance.
The parts E E' are held together by bolts e. The holes in the pin b which
receive the bolts e are sufficiently large to allow the friction blocks to oscillate on
the pin b.
To obtain the requisite frictional grip of the blocks E the toggle links H may
be adjusted as regards length by the nuts h. The toggle links H are split at f
and the bolts g are tightened so as to fasten the parts i and f together in their
adjusted length.
Fis the sliding sleeve. This contains a groove & for containing the flattened
heads of the pins 7 upon which the toggle links are pivotted together. A groove n
in the sliding sleeve F is provided for receiving the cod pieces of the lever used to
operate the clutch. When in the position shown in full lines of the drawings the
clutch is in gear. The dotted centre lines show the position of the toggles and
levers X when the clutch is out of gear. When out of gear the heads o of the inner
screws e bear against the boss of the driving arm d and so hold the blocks E at
rest when revolving, when the clutch is out of gear. It will be observed that by
means of the levers X greater frictional grip may be obtained on the clutch than
when the toggle links act directly upon the blocks E as shown in Figs. 1 and 2.
The arrangements shown in the drawings may be adapted to either couple two
shafts together, or to drive a loose pulley or wheel or sleeve revolving loosely upon
the shaft or in bearings concentric therewith.

page_text: 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. The general arrangement, construction and combination of parts composing
the improved friction clutch substantially as herein before described and as
illustrated on Sheet 1 of the drawings.
2. The general arrangement, construction and combination of parts composing
the improved friction clutch substantially as hereinbefore described and as
illustrated on Sheets 2 and 3 of the drawings.
3. In a friction clutch of the indicated nature the sliding sleeve F the boss D
with driving arms, the saddles G, the springs J with means for adjusting the
tension of the same, the toggle links H and friction blocks E all combined and
mounted upon a shaft such as C and operating in conjunction with the clutch
half A or its equivalent mounted upon a shaft such as B substantially as described
and as illustrated on Sheet 1 of the drawings.
4. In a friction clutch of the indicated nature, the sliding sleeve F, boss D¹ with
driving arms D compound friction blocks E E3 with interposed and self contained
elastic packing J, toggle links H, adjusting bolt P anchoring toggle links to
driving arms 1) and furnished with compressible jamb nut washer 12 all combined
and mounted on a shaft such as C and operating in conjunction with a clutch
half A or its equivalent mounted upon a shaft such as B substantially as described
and as illustrated on Sheets 2 and 3 of the drawings.
5. The general arrangement, construction and combination of parts comprising
the modified form of clutch substantially as described and illustrated in Figs. 11
and 12 of Sheet 4 of the drawings.
Dated this 21st day or
For the Applicant,
E. K. DUTTON & Co.,
5 John Dalton Street, Manchester, Chartered Patent Agents.