Year: 1888

page_text: EDWARD JOHN HOUGHTON of 1 Pilkington Road, Peckham S.E. Electrical
Engineer, do hereby declare the nature of this invention to bo as follows:-
When using dynamo machines for charging accumulators or other purposes it
happens sometimes that an abnormal amount of heat is developed on the commutators
of such machines which if not diminished or stopped may cause damage. To provent
such injury occurring I place under, over or in close proximity to, the commutators a
compound metal plate made of dissimilar metals such as zinc and steel, brass and
steel etc. and arrange it in such a manner that when the commutator is excessively
heated the heat radiating from it shall cause the plate to warp, bend or move in such
a manner as to disconnect a circuit or by interposing resistance lessen the work done
by the dynamo.

page_text: I, EDWARD JOHN HOUGHTON, of 1 Pilkington Road, Peckham, S.E. Electrical
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 :-
When using dynamo machines for charging accumulators or other purposes, it
happens sometimes that an abnormal amount of heat is developed on the commutators
of such machines which, if not diminished or stopped, may cause damage. To
prevent such injury occurring I place under, over, or in close proximity to the
commutator a compound metal plate made of dissimilar metals such as zinc and steel,
brass and steel etc. and arrange it in such a manner that when the commutator is
excessively heated the heat radiating from it shall cause the plate to warp, bend or
movo in such a manner as to disconnect a circuit or, by interposing resistance, lessen
the work done by the dynamo.
The accompanying diagrammatic drawing shews by way of example one arrange-
ment for carrying out my above described invention.
A is the commutator of a dynamo electric machine, and B is a plate or rod.
composed of two different metals in such manner as to bend when heated, as is well
understood.
One end of this plate is fixed to a stationary support D and is in electrical con-
nection with the one lead E of the shunt circuit of the dynamo, the other lead E¹ of
which is connected to a fixed contact point C. When the commutator A is at a
moderate temperature, the plate B remains in the dotted position in which it makes
contact with C and closes the shunt circuit. When the commutator becomes
heated to an abnormal degree, the heat radiated therefrom is partially taken up by
the plate Band this, in bending or warping, assumes the position shewn in full lines
in which it breaks contact with Cand thus interrupts the shunt circuit, until, on the
cooling down of the commutator and consequently also of the plate B, the latter
again assumes the dotted position, closing the shunt circuit.
It will be evident that the plate B, instead of interrupting the shunt circuit on
becoming heated may be caused to make a contact whereby a resistance is interposed
that reduces the work of the dynamo.

page_text: Having now particularly described and ascertained the nature of my invention
and in what manner the same is to be performed, I declare that what I claim is :-
The use, in combination with the commutator of a dynamo electric machine, of a
compound metal plate or bar made of two different metals placed in proximity to
the commutator and so arranged in connection with a circuit of the dynamo electric
machine or with a resistance, that on the commutator becoming abnormally heated the
compound metal plato in taking up a portion of the radiated heat, will bend or warp
and thereby interrupt the circuit or interpose the resistance so as to lessen the work
of the dynamo, substantially as herein described.