IMPROVEMENTS IN ELECTRIC CLOCKS
Year: 1881

page_text: LETTERS PATENT to Alexander Melville Clark, of 53, Chancery Lane, in the
County of Middlesex, Patent Agent, for an Invention of IMPROVEMENTS
IN ELECTRIC CLOCKS." A communication from abroad by Jakob Schweizer,
of Soleuro, Switzerland.
COMPLETE SPECIFICATION filed by the said Alexander Melville Clark at
the Office of the Commissioners of Patents on the 14th June 1881.
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of Middlesex,
Patent Agent. "IMPROVEMENTS IN ELECTRIC CLOCKS." A communication from
abroad by Jakob Schweizer, of Soleure, Switzerland.
This Invention relates to an electric clock, and in cer that it may be more
readily understood I have illustrated it in the accompanying Drawings, and will
describe it with reference thereto, and to the letters and figures marked thereon.
In this clock the barrel is dispensed with, and two wheels are employed, of
which the one A (Figure 1) is fixed on the arbor of the minute hand, and drives tho
motion work B which moves the hour hand. The other wheel C drives the pinion con
the escapement wheel arbor. With this arrangement the power is therefore applied
directly to the centre wheel by means of the mechanism which I will proceed to
describe scriatim, in order that the novel parts of this clock may be readily
understood.
Upon the arbor of wheel A is fixed radially a straight spring a, rather shorter than
the radius of the wheel. It is evident that if pressure be applied to the extremity
of this spring so as to bend it in the direction in which the wheel A should turn,
this wheel will follow the impulse given by the flexure of the spring, and actuate
the escapement to a corresponding extent. In order to obtain the constant motive
power necessary to keep the clock going regularly, it is only necessary that this
pressure should be continued without interruption. To this end a ratchet wheel D,
Figures 1 and 2, having fine teeth, rides loose upon the same arbor with wheel A,
and has a pin b fixed to it at one side near the circumference, which presses against
spring a near its extremity, as shown in Figure 1. The wheel D is rotated by tho

page_text: gravity of a weight P (Figures 2, 3, and 4) fixed on the extremity of a horizontal
lever E pivoted at F, upon which the weight is secured adjustably by means of a
set screw d, so as to act with greater or less leverage according to the amount of
power required. Pivoted to this lever E at e is a pendent arm or pawl G
(Figures 2 and 3), which hangs tangentially to the ratchet wheel D, and terminates
in a nib which is caused to engage with the teeth of the ratchet by a spring ƒ
(Figures 2, 3, and 4), pressing upwards against the curved tail end g of this pawl.
A uniform motive power is thus obtained so long as the weight P is free to descend,
and when it has fallen to its lowest point it is raised again by electrical action to
renew its operation. During the very short space of time occupied in raising the
weight P the ratchet wheel D continues to be turned by the stress of the spring a,
which is always bent to a certain extent, so that the motive power is maintained
without interruption.
I will now proceed to describe the means employed for raising the weight P
periodically by electric action. A battery (preferably a Leclanché battery, as it
does not give off any acid vapors) is placed in the clock case beneath the movement
with which it is connected by two wires attached by binding screws h to the two
terminals H, H, (Figure 5), one of which is in connection with the coils of the
electro magnet I through a device, the purpose of which will be explained
hereafter.
When the current passes in the coils of the electro-magnet I (Figures 2, 3, 4,
and 5) its armature K is attracted. This armature is pivoted between the two
plates of the clock frame upon a pivot i (Figure 4), and it carries two ears, between
which the weighted lever E is pivoted at F. An adjusting screw 7 (Figures 2 and
3) regulates the height of the lever E relatively to the ratchet wheel D. When the
armature K is momentarily attracted by the electro magnet, the lever E is raised,
the pawl G slides over the teeth of the ratchet wheel, and then the electric circuit
being broken, as will be presently explained, the armature K is liberated, and
allows the lover E to recommence its action on the ratchet wheel D, the power
being meantimo maintained without appreciable alteration by the stress of spring a,
as before explained. A spring click L upon an arbor mounted in the plates of the
frame engages constantly with the ratchet wheel D, and prevents any retrograde
movement during the rise of the pawl G.
I will now describe the means of determining with precision the closing and
breaking of the electrical circuit. The circuit through the electro magnet is closed
by the contact of a small plate of platinum with which a spring M (Figure 4) is
tipped, with a small stud also of platinum fixed on a small disc m in electrical
connection with the coils of the magnet, and is broken by the cossation of this
contact. The closing and breaking of the circuit is effected by the disc N
(Figures 1 and 4) carried by a canon or tubular arbor of insulating material upon
an arbor n (Figure 1) mounted at one end in the front plate, and at the other in
the cock o. Upon this arbor isfixed a lover arm p, to the end of which is jointed the
end of a connecting rod r, whose upper end is slotted at r', and connected to the
lever E by a pin playing freely in said slot. Upon the same arbor is also fixed
an arm terminating in a curved or segmental ratchet tooth rack, with which a
click at the extremity of one arm of an elbow lever pivoted at may be caused
to engago by the stress of a spring, or may be disengaged therefrom by a screw E¹
upon the lever E pressing on the horizontal arm 2 of said elbow lever. It will
thus be seen that as the lever E is raised it raises the arm p by the connecting
rod r, and as it falls it abuts upon the arm 15 of the elbow lever, disengages the
click, and allows the rack to fall. A slight alternate circular motion is thus
imparted to the arbor n and disc N. The effect of this movement is as follows :—
Figure 4 represents the position of the parts when the parts M, m, are in contact
and the current is established. The disc N carries a stud furnished with an
adjustable screw, which bears upon a horizontal spring u attached to an insulated
support. The disc N is also furnished with a pint for a purpose to be presently
explained. The electro-magnet I being excited by the passage of the current, the

page_text: armature K is attracted, and the lever E raised. By this movement, which may
be greater or less, according to the strength of the current, the rod r is raised by
the pin in the slot r', and the disc N slightly rotated in the direction of. the
arrow, in consequence of which the screw 8 ceases to press upon the spring u, and
the pint meets the spring M, and pushes it back beyond the extremity of the
spring u, which can thereupon return to its normal position, and prevent the return
of the contact spring M against the disc m until the screws again bears against
the spring u. On the breaking of the circuit, the screw E' of lever E having been
raised off the arm 7 of the elbow lever, the click is brought up by the spring 74
against the rack 5, as shown in Figure 2. The current having been interrupted
by the pint acting on the spring M, as described, the armaturo is released, and the
lever E begins to descend by the gravity of weight P, the connecting rod r, lever p,
arborn, rack, and disc N meanwhile remaining stationary in the position to
which they have been brought by the rise of lever E, until the screw E' presses
upon the arm of the elbow lever, as the lever E in descending has no action on
the connecting rod r, the pin 77 merely sliding down the slot r; but immediately
the screw E³ presses on the arm 7, as shown in Figure 3, the rack is released
and falls by its own gravity, bringing all the parts connected with it to the position
shown in Figures 3 and 4, in which the circuit is again closed, whereupon the parts
are returned to the positions shown in Figures 2 and 6, and the same action is
repeated continually so long as the battery is sufficiently strong to cause the
attraction of the armature K. The battery may in course of time become so weak
as to be incapable of producing this effect, and were the circuit to remain closed
there would be a useless wear of the battery. To prevent this the arrangement
before referred to and represented in Figures 2, 3, and 7 is provided. The contact
being established by spring M, it is necessary to break the circuit at the other
wire. For this purpose the other terminal H is in connection with the coils of
the electro magnet I through a cross bar H2 and a spring 1 attached to an
insulated support h. This spring has at its free end a small head ³ of insulating
material, which passes freely through a hole in the cross bar H, and projects
slightly above the upper surface thereof (Figures 2, 3, and 7). When the armature
K is no longer attracted by the electro magnet it descends until it meets the
insulating head h³, which it presses down and forces the spring h¹ away from
the bar H, thus breaking the circuit and automatically preventing waste of the
battery.
Having described the nature of the said Invention, and the manner of performing
the same, I declaro that what I claim as new, and desire to secure by Letters
Patent is,
1st. The improved electric clock constructed, arranged,.and oporating substan-
tially as herein described and shown in the Drawings.
2nd. An electric clock driven by a weight acting directly on the centre wheel,
substantially as specified.
3rd. In an electric clock a pawl moved alternately in opposite directions by a
weight and by olectric action, a ratchet wheel loose on the centre wheel arbor, a
pin on the ratchet wheel, a spring fixed on said arbor, and a click engaging with
the ratchet wheel, all combined to operate substantially as shown and described for
the purpose specified.
4th. The combination of the weighted lever and the armature lever connected
together at a variable angle, and acting reciprocally the one upon the other to
produce an oscillating movement on the one hand by electric action, and on the
other by a counterweight, substantially as shown and described.
5th. The mode of regulating the angular distance between the two levers by
means of a regulating screw, in order to determine the extent of upward movement
of the counterweight according to the strength of the current, substantially as
specified.
6th. The mechanism for periodically making and breaking the circuit, combined
to operate substantially as shown and described.

page_text: 7th. The device herein shown and described for breaking the circuit when the
battery is too weak to raise the counterweight, said device being operated by the
depression of the armature lever by the counterweight lever, substantially as
specified.
In witness whereof, I, the said Alexander Melville Clark, havo hereunto set
my hand and seal, this Fourteenth day of June, A.D. 1881.
A AL CLARK Gα)