Year: 1887

page_text: Date of Application, 22nd Aug., 1887
Complete Left, 18th May, 1888
Complete Accepted, 22nd June, 1888
THOMAS ALEXANDER GARRETT B.A. 80 Abingdon Road, Kensington, London
Engineer do hereby declare the nature of this invention to be as follows:-
B
This invention relates to methods and apparatus used to convey electricity to or
from bodies in motion, and has for its object improvements in such methods and
apparatus.
It is especially applicable to dynamo-electric machines and motors but may be used
in many other cases in which electricity is required to be conveyed to or from moving
bodies.
In the case of bodies revolving round axes such as the revolving armatures of
dynamo electric machines and motors, circular troughs revolving round the spindles
are used, these troughs preferably contain mercury which is in good electrical
connection with those parts of the armatures to which or from which currents are
to be conveyed. When the armatures are made to revolve the mercury, is kept
in the troughs by centrifugal force and the currents of electricity are conveyed to
or from the mercury by conductors or contact makers which dip into it.
When the spindles of the armatures are vertical the troughs will revolve in
horizontal planes and in this case the troughs may be so shaped that each will
retain its own mercury when the armature is stopped, cr that when the armature
is started the mercury will flow from a low trough into higher ones, a certain
quantity of mercury being retained in each trough.
The conductors or contact makers which dip into the mercury may be made of any
substance which conducts electricity and they may be small and of such a form that
they will easily cut through the mercury, or they may be in the form of rings or discs
dipping into the mercury all round their circumferences, or in the form of discs easily
turned round their axes, which discs may be by the use of mercury put in good
electrical connection with stationary conductors, or the contact makers may be of any
other form which is found convenient. Two or more of these forms may be used
together.

page_text: In place of mercury any other liquid conductor which is, suitable may be used,
and when found advantageous the mercury or this liquid conductor may be covered
by another liquid.
In order that the contact makers may continue to make good electrical contact with
the mercury in some cases it is found expedient to cause them to be rubbed by the
revolving trouglis containing the mercury or by rubbers attached to moving parts of
the machine or by separate rubbers provided for the purpose.
When the conductors or contact makers which dip into the mercury are stationary,
mercury may be supplied to the troughs through fine holes in the substance of these
conductors, which holes open or end under the surface of the mercury in the revolving
troughs when the apparatus or machine is working normally, the other ends of the
holes being in connection with reservoirs containing mercury. The distance to which
the mercury in a revolving trough will rise over a stationary contact maker will
depend partly on the height of the surface of the mercury in the reservoirs above the
end of the hole through which the mercury is supplied to the trough through that
contact maker, and the former may be varied or adjusted by varying the latter.
This adjustment may be automatic and may be brought about by electrical or by
mechanical means or by a combination of the two, when the amount of current
passing through the armature changes, or when the rate of revolution of the armature
changes, or when the difference of electrical potential between any two given points
in the circuit changes.
Some of the advantages of the indicated-methods of making electrical connection
with moving bodies are, that the mercury or other liquid conductor is prevented
by centrifugal force from being divided into small drops; that the friction or
resistance due to the connection may be made small since the surface of the liquid
in each trough is symmetrical or nearly symmetrical about the axes of revolution
and a contact maker need therefore only dip into the liquid a short way and still be
in continuous contact with it, and that the connection may be made perfectly
continuous.

page_text: COMPLETE SPECIFICATION.
Improvements in and Connected with Electrical Connections with
Moving Bodies.
I, THOMAS ALEXANDER GARRETT, B.A. of 80 Abingdon Road, Kensington, London,
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 :-
This invention relates to methods and apparatus used to convey electricity to cr
from bodies in rotary motion.
It is especially applicable to dynamo electric machines and motors but may be used
in many other cases in which electricity is required to be conveyed to or from
revolving bodies such as armatures of dynamo electric machines and motors.
I provide circular troughs revolving round the spindles, these troughs containing
mercury which is in good electrical connection with those parts of the armatures to or
from which currents are to be conveyed. When the armatures revolve, the mercury
is kept in the troughs by centrifugal force and the currents of electricity are conveyed
by conductors or contact makers which dip into the mercury.
When the axis of revolution is vertical the troughs revolve in horizontal planes
and in this case they may be so shaped that each will retain its own mercury when
the armature is stopped, or that when the armature is started the mercury will flow
from the lower to the higher troughs, a certain quantity being retained in each
trough.
The conductors or contact makers which dip into the mercury may be of such a
form as to offer little resistance to the mercury, or they may be in the form of rings
or discs dipping into the mercury all round their circumferences, or in the form of
discs free to revolve which discs may themselves be by the use of mercury put in
good electrical connection with stationary conductors.
In order that the contact makers may continue to make good electrical contact
with the mercury they may be arranged so as to be rubbed by the revolving troughs
or by separate rubbers.
When the conductors or contact makers which dip into the mercury are stationary,
mercury may be supplied to the troughs through them by holes which open under
the surface of the mercury when the machine is working, at normal speed, these holes
being in communication with reservoirs containing mercury. As the distance to
which the mercury in a revolving trough will rise over a stationary contact maker
depends partly on the height of the mercury in the reservoir above the hole through
which the mercury is supplied to the trough, this distance may be varied or adjusted
by varying the height of the reservoir. This adjustment may be automatically
effected by electrical or by mechanical means, when the speed of the armature or the
electrical potential or current changes.
Some of the advantages of the indicated methods of making electrical connection
with revolving bodies are, that the mercury is prevented by centrifugal force from

page_text: being divided into small drops; that the friction or resistance due to the connection
may be made small since the surface of the liquid in cach trough is symmetrical or
nearly so about the axis of revolution and a contact maker need therefore only dip
very little into the mercury still being in continuous contact with it, and that the
connection may be made uniformly continuous.
C
Fig. 1 of the accompanying drawings is a diagrammatic section shewing how two
or more electrical connections according to my invention may be applied to an
armature revolving round the axis D. Assuming the armature to consist of an inner
cylinder a and an outer cylinder & insulated from each other as indicated by the dark
line between them, I provide two circular trough spaces to contain mercury at b
and the former in metallic connection with a, the latter with d; they are separated
by an insulating partition through which there is a hole s or there may be several
such holes to allow the mercury to flow from the upper space to the lower when the
armature is at rest or to flow from the lower space to the upper when it is driven
outwards by centrifugal force as the armature rotates. There may with advantage
be an upper space e to receive any surplus of mercury from the lower spaces.
Obviously instead of two spaces b and c there may be a greater number similarly
arranged according to the number of separate connections required. The conduction
from the mercury in b and c may be effected simply by a wire or metal rod dipping
into it, this wire or rod being preferably thin and flat presenting sharp edges in the
direction of revolution so as to offer little resistance to the mercury. I prefer how-
ever to immerse in the mercury the edge of a conducting disc such as m shewn in
section by Fig. 2, which is free to revolve on a stationary conducting axis n, good
conduction being obtained by the boss of the disc being immersed in mercury in a
box secured to the axis n. Fig. 3 is a diagrammatic section shewing an arrange-
ment of electrical connection in which the immersion of the conductor in the mercury
may be varied. In this case an armature such as a revolving round axis D has
formed at its end an annular trough to contain the mercury in contact with the
edge p of the flange of a stationary conducting cylinder f. By a hole bored in fand
its flange the mercury can flow from a reservoir communicating with, and this
reservoir may be raised or lowered in level so as to cause more or less of the mercury
to flow into the trough in opposition to the centrifugal force which tends to drive
the mercury up to the reservoir.
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. For effecting electrical connections with two or more armatures or bodies
revolving on the same axis the arrangement of two or more annular troughs insulated
from one another and containing mercury in which separate conductors dip
substantially as described with reference to Fig. 1.
2. For making contact with a revolving body of mercury, the use of a dise free to
revolve on a stationary conducting axis, with its boss immersed in mercury contained
in a box attached to the axis, substantially as described with reference to Fig. 2.
3. For varying the immersion of the flange of a stationary conductor in a body of
revolving mercury, arranging in the conductor a hole putting the mercury in
communication with a reservoir that can be raised or lowered substantially as
described with reference to Fig. 3.