Improvements in Friction Clutches.
Year: 1892

page_text: Date of Application, 29th Mar., 1892
Complete Specification Left, 29th Dec., 1892-Accepted, 11th Feb., 1893
PROVISIONAL SPECIFICATION.
Improvements in Friction Clutches.
I, JAMES FRASER, Engineer, of 150 Cromwell Road, South Kensington, in the
County of Middlesex do hereby declare the nature of this invention to be as
follows:-
:
This invention for improvements in friction clutches has for its object to provide
improved means for gradually forcing the gripping surfaces into contact and for
firmly holding them in contact so as to prevent slip and consists essentially in
forcing the gripping surfaces into contact by means of the pressure of a liquid
caused by the relative motion of the two members of the clutch to flow through
a valve which is gradually closed by the operator so as to raise the pressure of the
liquid and force and hold the gripping surfaces in contact.
In a clutch constructed according to this invention one member of the clutch is
provided internally with two or more cylinders arranged parallel to the axis and
diametrically opposite one another and communicating with one another by
passages and a combined valve and displacement chamber in which works a
combined valve and displacer or plunger valve. In each cylinder is a plunger or
piston, the outer or free end of which is adapted to bear on a cam surface fixed on
the other member of the clutch. The cylinders and chamber contain a suitable
liquid such as oil. The operation is as follows:-When desired to put the clutch
in gear, the plunger valve, is forced further into its chamber, and forces out the
plungers against the cam surface. The relative motions of the two members of
the clutch operates the plungers which reciprocate so as to keep up a flow of
liquid between the two cylinders and through the valve chamber. On forcing
the plunger valve further into the chamber the valve gradually closes the
communication between the two cylinders and the pressure of the plungers against
the cam surface increases and forces the two members of the clutch into firm
contact and holds them there. To disengage the clutch it is only necessary to
withdraw the plunger valve when the plungers will be drawn into their cylinders
out of contact with the cam surface and the members disengage themselves. The
displacement chamber is in communication with a reservoir provided with a spring
piston, so that when the oil attains a certain pressure due to the action of the
plunger valve the surplus oil passes into the reservoir and raises the piston. The
plunger valve cuts off all communication between the reservoir and the cylinders
as soon as it begins to close but all further oil displaced by its further movement
passes to the reservoir.
The plungers may be forced against and withdrawn from the cam surface by
mechanical means instead of hydraulic.
Dated this 29th day of March 1892.
WHEATLEY & MACKENZIE,
40, Chancery Lane, London, Agents.
COMPLETE SPECIFICATION.
Improvements in Friction Clutches..
I JAMES FRASER, Engineer of 150 Cromwell Road, South Kensington, in the
County of Middlesex, 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 :-
This invention for improvements in friction clutches has for its object to provide

page_text: improved means for gradually forcing the gripping surfaces into contact and firmly
holding them in contact so as to prevent slip; and consists essentially in forcing
the gripping surfaces into, contact by liquid pressure produced by the flow of the
liquid, caused by the relative motion of the two members of the clutch through a
valve that can be gradually closed to increase the pressure of the liquid.
In a clutch constructed according to this invention one member of the clutch is
provided internally with two or more cylinders arranged parallel to the axis and
diametrically opposite one another and communicating with one another by
passages and a combined valve and displacement chamber in which works a
combined valve and displacer or plunger valve. In each cylinder is a plunger or
piston the outer or free end of which is adapted to bear on a cam surface fixed on
the other member of the clutch. The cylinders and chamber contain a suitable
liquid such as oil. The operation is as follows:-When desired to put the clutch
in gear the plunger valve is forced further into its chamber and forces out the
plungers against the cam surface. The relative motion of the two members of
the clutch operates the plungers which reciprocate so as to keep up a flow of
liquid between the two cylinders and through the valve chamber. On forcing the
plunger valve further into the chamber the valve gradually closes the communi-
cation between the two cylinders and the pressure of the plungers against the
cam surface increases and forces the two members of the clutch into firm contact
and holds them there. To disengage the clutch it is only necessary to withdraw
the plunger valve when the plungers will be drawn into their cylinders out of
contact with the cam surface and the members disengage themselves. The
displacement chamber is in communication with a reservoir provided with a spring
piston so that when the oil attains a certain pressure due to the action of the
plunger valve the surplus oil passes into the reservoir and raises the piston. The
plunger valve cuts off all communication between the reservoir and the cylinders
as soon as it begins to close but all further oil displaced by its further movement
passes to the reservoir.
In the accompanying sheet of illustrative drawings:-Figures 1 and 2 are
longitudinal sections on the lines A-A B-B Figure 4 respectively of a friction
coupling constructed according to this invention and Figure 3 is an end elevation
and Figure 4 is a transverse section on the line C-C Figure 1 of the same.
The outer cone D of the clutch carries internally two cylinders 1 communicating
by the passages 2 with the valve chamber 3 in which works the combined valve
and displacer 4. The plungers 5 work in the cylinders 1 and their outer ends
bear against the inclined surface 6 on the end of the inner cone E of the clutch.
The cylinders 1 and chamber 3 are filled with oil and when desired to put the
clutch in gear the displacer 4 is moved toward the right, Figure 1 and forces the
oil below it through the passages 2 behind the plungers which are thus forced
against the inclined surface 6. The relative motion of the cones D and E then
causes the plungers 5 to reciprocate by the action of the inclined surface 6 on their
outer ends and to cause a flow of oil in the passages 2 alternately in the opposite
direction. On still further depressing the valve or displacer 4 it gradually closes the
ports 7 of the passages 2 and thus opposes a gradually increasing resistance to
the flow of oil and consequently to the notion of the plungers 5 which thus force
the inner cone E into the outer cone D with a gradually increasing pressure so
that the two gradually attain the same speed and are held firmly in gear. To
disengage the clutch, the valve or displacer 4 is moved toward the left, Figure 1,
and sucks the oil from behind the plungers 5 which are thus drawn into their
cylinders and out of contact with the inclined surface and the cones D and E
disengage themselves..
In order to ensure the free motion of the valve or displacer 4 when it covers or
partially covers the ports an oil reservoir F is mounted on the sleeve 8 by means
of its strap 16 so that it can be held stationary whilst the sleeve rotates and is
provided with a piston 9 forced downwards by a spring 10. The chamber 3
communicates with the reservoir F below the piston 9 through the passage 10 in

page_text: the displacer, groove 11, passage 12, circumferential groove 13 and hollow
guide 14.
When the oil in the chamber 3 attains a certain pressure it is forced
into the reservoir F and raises the piston 9 on its guide 14 and escapes between it
and the guide 14 whose diameter is reduced above to allow of the escape of air
and of oil. When the ports 7 are being covered the inner end of the valve or
displacer 4 enters and fits the reduced end of the chamber 3 and so shuts off
communication between the cylinders 1 and the oil reservoir. Any vacancy after
the plungers are withdrawn is made up by fluid drawn from the oil reservoir. Any
leakage of oil passes by the holes 15 into the reservoir F and oil can be added
through the same holes and passes between the guide 14 and piston to the clutch.
The reservoir F is mounted on a sleeve so that it is stationary and oil can be added
when the clutch is running. If desired however the reservoir F with slight
modification can be rigidly fixed to the outer cone D and in direct communication
with the inner end of the valve chamber 3, but in this case it is necessary to stop
the mechanism to add oil. The valve or displacer 4 is operated in any usual
manner, such as a lever connected to the projection 17 on the strap 16 the said
lever preventing the reservoir F from rotating with the coupling.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, would have it
understood that I do not desire to claim anything contained in my prior Letters
Patent No. 2607 of 1890 but I declare that what I claim is :-
1. A hydraulic friction clutch in which the gripping surfaces are forced into
contact by liquid pressure produced by the flow of the liquid, caused by the
relative motion of the two members of the clutch through a valve that can be
gradually closed to increase the pressure of the liquid, substantially as described.
2. A hydraulic friction clutch in which the gripping surfaces are forced into
contact by liquid pressure produced by the flow of the liquid, caused by the
relative motion of the two members of the clutch, through a valve that can be
gradually closed to increase the pressure of the liquid and in which any waste of
liquid is supplied from a reservoir attached to the clutch substantially as
described.
3. A hydraulic friction clutch in which the gripping surfaces are forced into
contact by pistons or plungers working in cylinders arranged in one member of
the clutch and communicating by passages with a valve chamber in which is a
displacer valve acting first to force the rods of the pistons or plungers against a
cam surface situated on the other member of the clutch and reciprocating the
pistons or plungers on any relative motion of the two members of the clutch, and
secondly to oppose an increasing resistance to the flow of liquid due to the said
reciprocation and consequently to increase the pressure by which the rods or
pistons are forced against the cam surface and thus the pressure forcing the
gripping surfaces into contact.
situated on one
4. A hydraulic friction clutch consisting of a cam surface
member of the clutch, of plungers or pistons 5 working in cylinders 1 situated in
the other member of the clutch, of a valve chamber 3 communicating by
passages 2 with the cylinders 1, and of a displacer valve 4 in the valve chamber,
serving first to force the pistons 5 against the cam surface 6 which reciprocates
the pistons 5 and gradually increasing the resistance in the passages 2 to the flow
of the liquid caused by the reciprocation and consequently the pressure of the
liquid and pressure between the gripping surfaces.
5. A hydraulic friction clutch consisting of a cam surface 6 situated on one
member of the clutch, of plungers or pistons 5 working in cylinders 1 situated in
the other member of the clutch, of a valve chamber 3, communicating by
passages 2 with the cylinders 1 and of a liquid reservoir F and of a displacer
valve 4 in the valve chamber serving first to force the pistons against the cam
surface 6 which reciprocates the pistons 5 and gradually increasing the resistance

page_text: in the passages 2 to the flow of the liquid caused by the reciprocation and
consequently the pressure of the liquid and pressure between the gripping
surfaces.
Dated this 29th day of December 1892.
WHEATLEY & MACKENZIE.
40, Chancery Lane, London, W.C., Agents.