Improvements in Friction Clutches.
Year: 1897

page_text: Date of Application, 23rd Feb., 1897
Complete Specification Left, 23rd Nov., 1897-Accepted, 15th Jan.,
1898
"
Improvements in Friction Clutches.
I, HENRY WRAY METCALFE, of 36, Balls Road, Claughton, Birkenhead, in the
County of Cheshire, Engineer, Royal Navy, do hereby declare the nature of this
invention to be as follows:-
According to this invention, I so connect the Revolving Shaft, or other driving
part with the part to be driven, that the power can be communicated in one
direction only, and such communication can be made or broken at will, whether
the driven part be at rest or in motion. If desired, by a partial reversal of the
action, the clutch may be made to transmit only a given amount of force to the
part driven, any excess of power in the driving part causing slip in the clutch
itself.
The arrangement I adopt is as follows:-
To the driving part, I attach a drum or cylinder bored on the inside, and capable
of resisting bursting pressure. Within this drum is placed a band, or spring ring,
cut through at one point.
"
A "tripper" or tumbling lever is so arranged, using a block attached to one end
of the band as fulcrum, and acting on the other end, that, by forcing the "free
end of the tripper in one direction or other, the band is distended or contracted,
as the case may be.
The "free"end of this tripper is connected either directly, or through springs
or other means, with the shaft or part to be driven, which is arranged concentrically
with the drum.
The ends of the band are kept apart with more or less force, by means of spring
action, either of the band itself, or of separate springs acting thereon, thus keeping
the band in contact with the interior of the drum.
On revolving the drum in one or other direction,-the part to be driven being at
rest, it is obvious that the band will be caused to revolve in the same direction,
by reason of its contact with the interior of the drum.
If this direction of rotation be such as to cause the " tripper" to distend the
band, the part to be driven still remaining at rest, the pressure of the band inside
the drum will be increased to such a point as to prevent slip,-the band will con-
tinue to revolve with the drum, and will transmit its motion through the
tripper" to the part to be driven.
If, on the other hand, the direction of rotation be such as to cause the "tripper"
to contract the band, the part to be driven still remaining at rest,-the pressure
of the band inside the drum will be reduced to such a point as to allow of free slip,
and no motion will be transmitted.
It is obvious that, if the position of the "free" end of the "tripper," in relation
to the part to be driven, and to the band, be under control, the band may at any
time be contracted, and the driving power,-where the direction of motion is
suitable, broken.
When it is desired to transmit only a certain definite force through the clutch,
in one direction only, the direction of rotation will be such as to free the band in
the drum, and the requisite pressure will be maintained between the band and the
drum by means of springs of suitable strength, tending to distend the band.
J

page_text: When the power transmitted exceeds that for which these springs are intended,
the "tipper
"will come into action to ease the pressure between band and drum,
caused by the springs, and so allow the band to slip, though the driving force will
still be maintained.
This action of the " tripper," and the slip allowed thereby, is obviously
applicable for governing the motive power of the driver.
Dated this Twentieth day of February 1897.
Improvements in Friction Clutches.
I, HENRY WRAY METCALFE, of 9. Woodford Villas, Mannamead, Plymouth, in
the County of Devon, Engineer, Royal Navy, late of 36. Balls Road, Claughton,
Birkenhead, in the County of Cheshire, do hereby declare the nature of this inven-
tion 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 so connect the revolving shaft or other driving
part with the part to be driven, by means of a Friction Clutch, that only a given
amount of force can be transmitted to the part driven, any excess of power in the
driving part merely causing slip in the connecting clutch. By a partial reversal
of the action of the clutch, and the introduction of suitable controlling mechanism
this device may be made to act as an ordinary Friction clutch, driving in one
direction only.
Figure 1. is a Front elevation, and Figure 2. a side section of the arrangement
I adopt, while Figure 3 is a front elevation, partly in section and Figure 4. is a
side section of the device when applied as an ordinary controllable Friction Clutch.
A drum or cylinder B is attached to the revolving shaft or driving part A.
This drum is bored concentrically with the driving shaft, and is capable of with-
standing bursting pressure. A cover L is provided, to keep the parts of the
mechanism in place.
Within this drum is placed a band or spring ring D. cut through at one point.
A Tripper, or tumbling lever E. is so arranged, using a pin F in a block F
attached to one end of the band as fulcrum, and acting on the other end through
the pin G and the block G, that by forcing the free end of the tripper in one
direction or other, the band is distended or contracted within the drum, as the case
may be.
The free end of this tripper is connected either by a sliding joint, or through
springs or other equivalent means, with the shaft or part to be driven, C.
In Figures 1 and 2. this connection is shewn, as made by means of the clock
spring K, which may, if necessary, be enclosed in a cylinder M', as is done in the
case of some clocks, the cylinder being attached to the tripper by means of the
pin M. and to the outer end of the spring, the inner end of which is in turn
artached to the shaft C, which is to be driven and which is arranged concentrically
with the drum or cylinder B.
The ends of the band D are kept apart with more or less force, by means of
spring action, either of the band itself, or of separate springs acting thereon, as
shewn at H. in Figures 1 and 2, or by similar means, thus keeping the band dis-
tended, and in contact with the interior of the drum B.
On revolving the drum in the direction shewn by the arrow in Figure 1., the
band being held in contact with the interior of the drum by the distending action
of the spring H. the band will be carried round with the drum, and so, through

page_text: the trinner E. will coil the spring K, and so transmit torsional force to the shaft C.
which is the part to be driven.
Should the resistance to rotation of the shaft C. be sufficiently great, the
spring K, will, on being coiled to a given point, overcome the distending force of
the spring H., the tripper will assert itself, and the band will be cased within the
drum, thus allowing of slip between the band and drum, the force on the
spring K still remaining practically constant.
Should this force be in any wise diminished, the spring H will again overcome
the spring K, and the pressure between the band D, and the interior of the drum
increased, until the torsional force of the spring K again reaches the normal, and
the balance of the forces adjusts itself.
Thus, whatever the speed of rotation of the part A, and so of the drum B. a con-
stant torsional force will be transmitted to the shaft C. provided that the speed of
rotation of the part A. be at least equal to that of the part C. and that the power be
sufficient.
When the device is applied as an ordinary Friction clutch, driving in one direc-
tion only, the direction of motion will be reversed, as shewn by the arrow in
Figure 3.
The springs H and K. will be dispensed with, and the part C will be connected
directly with the tripper, by means of the arm C., at a suitable point, at or within
the point F. The free end of the tripper will be actuated by a collar n. furnished
with a fork n engaging the end of the tripper. This collar can be rotated in
relation to its position to the part C. by means of the plunger rod O. placed within,
and revolving with that part, but capable of longitudinal motion, controllable
from without by means of a sliding sleeve p. on the part C. pinned to O. and
actuated by an ordinary striking lever. This plunger rod is prevented from turn-
ing in the part C. by means of the pin connecting it with the sleeve p. which works
in a longitudinal slot in the part C.
It is provided with a stud 7 working in a fast screw thread cut on the inside of
the collar n. in such manner that on causing the plunger rod O. to move longitu-
dinally within C. the collar n. will be caused to alter its angular position with
regard to the part C. thus actuating the tripper through the fork n¹, and distending
or contracting the band D within the drum B. and so making or breaking the con-
nection between the driving part A. and the part to be driven, C.
The effect of bringing increased strain on the clutch will merely be to increase
the intensity of the pressure between the band D and the drum B, through the
action of the tripper, thus increasing the resistance to slipping in the clutch.
Although I have shewn and described the tripper as actuated by this particular
method, it is obvious that any equivalent device for actuating it will be equally
suitable.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is:
1. The combination of an internal band brake, within a drum, with a tripper
actuating it, through which the power is transmitted to the part to be driven, either
direct, or through springs, substantially as described.
2. The combination of a controlling mechanism, either automatic, or actuated
through external means, with the said tripper, substantially as described.
3. Friction clutches, substantially as described and shewn in the drawings.
Dated this Twentieth day of November 1897.
HENRY WRAY METCALFE.