IMPROVED ELECTRICAL TORSION PENDULUM
Year: 1884

page_text: I ALFRED JULIUS BOULT of 323 High Holborn in the County of Middlesex
Engineer do hereby declare the nature of the said invention for "IMPROVED
ELECTRICAL TORSION PENDULUM (a communication from Gebrüder Rabe of
Hanau on the Maine German Empire) to be as follows:-
"
This invention relates to a torsion pendulum driven by electricity by receiving
an impulse from 'an electro magnet the pendulum automatically closing. at the
proper time an electrical circuit exciting the magnet.
A convenient form or construction of this improved pendulum may be described
as follows but considerable variations may be made, as for instance. the magnet
being placed in the pendulum instead of being made as hereunder specified.
The torsion-ribbon or strip consists as usual of a strip of steel or other suitable
material and is suspended at the top communicating in the usual manner with
clock work or other mechanism requiring to be regulated. The lower end of tho
torsion strip is clamped to a rod and a weight or bob is suspended from the latter.
In the lower part of the weight is provided an armature of suitable shape placed
on a level with the poles of the electro-magnet hereinafter referred to.
The weight rotates between the poles of an electro magnet there being as little
clearance between these as practicable.
In suitable position on the pendulum rod there is an adjustable arm fixed by a
set screw and sleeve this arm carries a hinged pawl or tooth. From the casing of
the apparatus or other suitable support projects a spring carrying a small shallow
trough or the like into which the pendulum pawl may take. The bottom of the
trough when depressed closes a circuit by touching contact pieces on an arm beneath
the trough supporting spring. The closing of the circuit sends a current through
the electro magnet, the armature in the pendulum-weight is attracted and a fresh
impulse given to the pendulum.
Whilst the torsional power is sufficient the pendulum pawl rides over the trough
without depressing it thus leaving the circuit broken when the torsion weakens,
this pawl becomes caught and causes the circuit to be completed as stated.
Dated thin with d

page_text: The contact device is capable of rotation; on one side it rests by pin in the
wall or side m of the clock at the other side by pink in a metal bracket 1. The
bracket is connected with the negative pole of an electric element placed in
the upper part of the clock. The pin i leads from the side or wall m into a glass
vessel n filled or nearly so with mercury.
screw
On the upper part of this vessel is provided a conducting wire o which by
connected with the arbor and consequently with the projection h.
When the pendulum turns on its own axis the pin g slides over the projection or
pawl and its flange or rim q, when however the angle of rotation has decreased
to a certain extent then pin g will press against the rim or flange 9 and causes the
contact device F to turn slightly on its axis. In this rotation the mercury-cup n
(likewise circular in transverse section) is also rotated or tilted and the conducting
wire o is brought into contact with the quicksilver, see figure 1b.
The pin which leads into the mercury-cup is connected by the wires and
through the electromagnets with the positive pole of the electrical element, con-
sequently the mercury is charged with positive electricity whilst the wire o, being
connected by screw p with r, is charged with a negative current.
Now when the contact device F moves as above set forth the wire charged
with electricity comes in contact with the mercury charged with electricity,
the circuit is thus closed, the electromagnets are excited and by the effect of the
magnetic force upon the armature the latter is attracted for a short time and a
fresh impulse is imparted to the pendulum.
When the ping has passed across the flange q and contact is made by the rotation
of the contact device the latter is brought back to its previous position by gravity.
Figure 2 shows a modification of the contact device. The prismatic or wedge
shaped piece t is attached to the arm E of the pendulum rod D in such a manner
as to be perfectly free to move. This piece slides over a recessed piece u upon
the spring F; when the angle of torsion diminishes, a moment will arrive when
the piece t no longer slides over the recessed piece u (figure 2) but presses upon
the same (figure 2b) and this causes the springs u¹ upon u to bear against the
piece and thus to ostablish connection for the current passing through F and
through . At the same moment the circuit is completed and the electro magnet is
excited. In this form of contact device also the pendulum closes the circuit at the
moment when the angle of oscillation has decreased to a certain degree.
The lower part G of the pendulum rod (figure 3) serves for the reception of the
rod D which is suspended on the pin X.
On sheet II however Figure 4 illustrates a different manner of suspending the
said rod, viz, by a bayonet-fastening.
The upper part of the pendulum rod in one form of this pendulum consists in a
steel-ribbon 8 (see sheet I figure 3 and sheet II figure 4) upon which there is n
piece w (sheet I figure 3, in sheet II figure 4); this piece is used for driving the
mechanism as will hereinafter appear.
In another form the upper part is a simple metal wire L (sheet I figure 5). In
the latter form there is upon the pendulum rod a spiral spring M, placed at 2, the
free end whereof is attached to the sides of the clock case. When the pendulum
swings round, in the case illustrated by the drawing towards the right, the spiral
spring is coiled or twisted up and when uncoiling causes the pendulum to swing
into the other direction.
The other parts would be analogous in both forms.
The transmission of the oscillation to the works is effected through the wheel H
(Sheet II figure 4) by a tooth k. The toothed wheel is in its upper part covered
with a cap or hood m provided with an indentation or recess u having for its object
to prevent the tooth coming into engagement with the wheel at any but the right
place. The tooth k is loosely mounted in the piece i so that it is capable of a slight
up and down motion. The pendulum is suspended from an arm or beam G (figure 4
sheet II) fitted with a screw O and this, together with a piece p and a slotted
plate p' govern the oscillation of the pendulum allowing the clock to be regulated.

page_text: On sheet II is shown a modification of the electrical driving mechanism wherein
the electro magnet and armature are entirely independent of the pendulum.
The armature A shown in Figure 1 is fixed on a rod a free to rotate in b and is
connected with a spiral spring c which is twisted up when the circuit is completed,
that is to say when the armature A is attracted by the electromagnet, this spring
causes the armature to reassume its previous position as soon as the same ceases to
be capable of exerting any magnetic force.
The armature A is placed on a brass plate K (figures 1, 3, 3º) whereon a pin d is
provided; at its upper part there is a plate F having two projections e which have
for their object to strike against the pins f in the bottom plate D of the pendulum
weight (Figure 2) when the armature bears against the poles of the electromagnet;
this imparts a fresh impulse to the pondulum. The plate F has slots g, through
these screws pass and are attached to the armature A in such a manner that they
allow the plate freely to move to-and-fro. The latter has on one side a shoulder or
extension i recessed at . When the armature is attracted by the electro magnet,
the plate F is by means of the piece and the pin d caused to slide towards the
right and then the two projections e come close behind the pins f of the pendulum
weight. When the armature goes back the plate F is caused to go to the left again
viz, by the recess i piece and pin d, the pins f of the pendulum weight are then
again free to rotate round the axis of the pendulum. By mounting the armature
in this manner the pendulum may when the circuit closes, receive such an impulse
that the angle of oscillation will not diminish sufficiently to cause the circuit to be
completed until after about 40 minutes. This calls for less use of the electrical
element thus increasing the life of the same.
On the frame shown in Figure 5 all the main parts of the clock are fixed in such
a manner that the clock and the pendulum form independent parts. The works of
the clock may be very simple and with or without striking train.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed as communicated
to me by my foreign correspondent I declare that what I claim is
1. The employment of an electrical driving mechanism for torsion pendulums
with automatic completion of the circuit by means of a fixed electro magnet and
of an armature provided upon the pendulum for the purpose of imparting an
impulse to the latter at the instant when the swing of the pendulum has decreased
to a certain extent.
2. In torsion pendulums driven by electricity the employment of an armature
and an electro magnet which are independent of the pendulum substantially in the
manner specified.
3. In the armature A the employment of a plate F (Sheet II Figures 3 3ª) so
constructed that when the armature bears against the poles of the electromagnet,
the pendulum receives an impulse by the projections e on the plate and the pins f
of the pendulum weight.
4. In torsion pendulums driven by electricity the arrangement of a contact
device by means of which the penduluin automatically closes the circuit and causes
the electro magnet to be excited.
Dated this 8th day of June 1885.