Improved Form of Magnetic Clutch.
Year: 1895

page_text: Date of Application, 22nd Mar., 1905
Complete Specification Left, 23rd Dec., 1895-Accepted, 8th Feb., 1896
Date of Application, a maj
Complete Specification Left, 23rd Dec., 1895-Accepted, 8th Feb., 1896
PROVISIONAL SPECIFICATION.
Improved Form of Magnetic Clutch.
BERNARD MERVYN DRAKE and JOHN MARSHALL GORHAM, Electrical
Engineers, both of 66, Victoria Street, Westminster, S.W. and Major HENRY
CAPEL LOFFT HOLDEN of Her Majesty's Royal Artillery, The Eaves,
Belvedere, Kent do hereby declare the nature of this invention to be as
follows:-
To provide a magnetic clutch for the transmission of power by rotary or other
movements, this clutch being not only certain but also rapid in its action in connecting
and disconnecting, and requiring the minimum of electrical energy to actuate it.
The clutch consists of two main portions, one of which constitutes the electro
Either one
magnet and the other the armature of this same electro magnet.
of these can be fixed to the driving shaft, the other being fixed to the driven
shaft. The electro magnet consists of an iron or steel disc securely fixed to its
shaft, and of suitable dimensions to allow of an annular coil of insulated wire
(which may for the sake of convenience be wound on a bobbin) being placed in an
When
annular recess concentric with the disc below the surface of its front face.
the electric current is passed through this coil the surface of the disc becomes
strongly magnetic. A cylindrical sleeve is attached to or forms part of the rear
face of the disc and this sleeve carries two, metal rings insulated from each other
and from the sleeve itself, these two metal rings are connected one to each end of
the wire coil, and may have grooves turned in them so that electrical connection
may be made and maintained with the coil by means of flexible conductors, springs,
or the like bearing in these grooves and connected to the source of electricity
whilst the disc and sleeve are revolving. The other portion of the. clutch is formed
of a second disc of iron or steel constituting the arinature of the electro magnet,.
the face of this disc is parallel and also opposed to the face of the electro magnet.
This second disc or armature is not fixed to the same shaft as the electro magnet
but may be loose on this shaft or may be attached to an entirely separate shaft,.
according to circumstances. Between the face of the armature disc and the
electro-magnet disc is placed a thin disc of iron or steel, the object of which is to
prevent the armature adhering to the electro magnet when the current is cut off,
which purpose it effects without increasing the resistance of the magnetic circuit
to any appreciable extent. The current through the coil of the electro magnet,
and thus the action of the clutch, is controlled by a switch or circuit closer and
opener such as are ordinarily used for electrical purposes.
T: oond day of March 1895.
B. M. DRAKE.
J. M. GORHAM.
H. CAPEL L. HOLDEN.

page_text: We BERNARD MERVYN DRAKE and JOHN MARSHALL GORHAM, Electrical
Engineers, both of 66, Victoria Street, Westminster, S.W. and Major HENRY
CAPEL LOFFT HOLDEN of Her Majesty's Royal Artillery, The Eaves,
Belvedere, Kent, 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 :--
To provide a magnetic clutch for the transmission of power by rotary or other
movements, this clutch being not only certain but also rapid in its action in con--
necting and disconnecting, and requiring the minimum of electrical energy to
actuate it. The clutch consists of two main portions, one of which constitutes the
electro magnet and the other the armature of this same electro magnet. Either
one of these can be fixed to the driving shaft, the other being fixed to the driven
shaft. The electro magnet consists of an iron or steel disc securely fixed to its
shaft, and of suitable dimensions to allow of an annular coil of insulated wire
(which may for the sake of convenience be wound on a bobbin) being placed in au
annular recess concentric with the disc below the surface of its front face. When.
the electric current is passed through this coil the surface of the disc becomes
strongly magnetic. A cylindrical sleeve is attached to or forms part of the rear
face of the disc and this sleeve carries two metal rings insulated from each other
and from the sleeve itself, these two metal rings are connected one to each end of
the wire coil, and may have grooves turned in them so that electrical connection
may be made and maintained with the coil by means of flexible conductors, springs,
or the like bearing in these grooves and connected to the source of electricity
whilst the disc and sleeve are revolving. The other portion of the clutch is
formed of a second disc of iron or steel constituting the armature of the electro
magnet, the face of this disc is parallel and also opposed to the face of the electro
This second disc or armature is not fixed to the same shaft as the
electro magnet but may be loose on this shaft or may be attached to an entirely
separate shaft according to circumstances.
Between the face of the armature disc
and the electro magnet disc is placed a thin disc of iron or steel, the object of
which is to prevent the armature adhering to the electro magnet when the current
is cut off, which purpose it effects without increasing the resistance of the magnetic
circuit to any appreciable extent. The current through the coil of the electro
magnet, and thus the action of the clutch, is controlled by a switch or circuit closer
and opener such as are ordinarily used for electrical purposes.
magnet.
Three descriptions or forms of the clutch are shown in the figures.
In Figure 1A is the soft iron disc having a coil of insulated wire C imbedded
in it the ends of which wires are led out to insulated rings of metal W W.
This disc is keyed by the key D to the shaft S so as to revolve with it.
The pulley P slides and revolves on the sleeve E which does not touch the
shaft S but is supported by the bracket B.
This pulley P may be made wholly of soft iron or only part of it, that is the
face opposed to that of A may be of soft iron the remainder being of other or
non-magnetic metal.
Between the opposed faces of A. and P is a thin disc of soft iron or steel F which
may either be loose on the shaft or attached to either A or P loosely, but not to
both of them.
The object of this disc is to prevent the two opposed surfaces of A & P from
adhering together after the clutch has been in operation and the current cut off
from the coil C.

page_text: The operation of the clutch is as follows:-
The shaft S being revolved carries with it the disc A, the pulley P remaining
at rest on the sleeve E.
The electric current conveyed to the coil C through the rings W W on which
are brushes, wires, carbon rods or analogous devices to convey the electric current
from the point where it is generated is then turned on and the face of A being
strongly magnetised attracts the face of P and the two adhere strongly together
revolving as one piece so long as the current continues to flow :
On the current being interrupted the magnetism disappears and P no longer
continues to rotate.
not rotate at all. In this case
In Figure 2. the arrangement of parts is so modified that the coil C is fixed and does.
is fixed to a continuation of the sleeve E as clearly
shown in the figure, the recess for the coil is in the pulley P and not in the disc A
as in Figure 1 the coil C being fixed the necessity for the rings W W is done
away with and merely the wires W W are required. The action is the same as-
that of the clutch shown in Figure 1.
Figure 3 shows another arrangement with a fixed instead of a revolving coil.
In this case the coil C is carried in the interior of a soft iron ring R which.
encircles the whole of the magnetic portion of the clutch and protects it mechanically
the disc A and the pulley P are both recessed equally to allow the coil to be clear
of them when one or both of them revolve.
The interior of the ring R is as close as possible to, but does not actually touch
the exterior surfaces of A and P. In this case also the action of the clutch is
identical with that described in Figure 1.
Having now particularly described and ascertained the nature of our said inven-.
tion, and in what manner the same is to be performed, we declare that what we
claim is :-
1. The use of a thin disc of soft iron or steel between the opposite faces of the
clutch which disc may either be loose on shaft or attached loosely to either side of
the clutch, but not to both of them.
2. The combinations substantially as described and for the purposes set forth.
Dated this 21st day of December 1895.
B. M. DRAKE.
JOHN MARSHALL GORHAM..
H. CAPEL L. HOLDEN.