Improvements in Clock Movements and the like.
Year: 1889

page_text: ale of Arp'ication, 10th Dec., 1389-Accepted, 25th Jan. 1890
COMPLETE SPECIFICATION.
Improvements in Clock Movements and the like.
I, HENRY SMITH PRENTISS of 1264 Waverly Place Elizabeth in the County of
Union and State of New Jersey in the United States of America, Mechanical 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:-
1
My invention has reference to improvements in mechanical motors and especially to
such as are adapted for use in cases where uniformity of motion and a constant
impulse are essential, such for instance as motors for operating the feed rolls of
magnesium lights or in clock or watch movements. Primarily the object of my
invention is to obtain by the use of purely mechanical means, a practically uniform
impulse, especially in spring motors, where otherwise the impulse varies with the
variation of tension in the springs. My improvement is therefore especially
applicable to time pieces, which in consequence thereof can be supplied with very
powerful main-springs and will run accurately for a long period of time without
rewinding, the effect on the pendulum or other timing devices being constant
regardless of the tention of the main springs.
With the above object in view, I combine with a motor, an equalizing spring
which is connected with and continually actuates a moveable member of the motor;
said spring being wound up at predetermined intervals by the motor, all of which
is more fully pointed out in the following specification and claim and illustrated in
the accompanying drawings, in which :-
Figure 1. represents a vertical section in the plane xx, figure 2, of a spring motor
embodying my invention.
Figure 2, is a vertical section thereof in the plane, y. y. figure 1.
Figure 3. is a section in the plane zz, figure 2, showing the equalizing device.
Figures 4 and 5 are detail views.
Figure 6, is a section in the same plane as figure 1, but showing the parts in
different relative positions.
Figure 7, is a sectional elevation showing my improvement applied to a clock
movement.
Figure 8, is a vertical section in the plane ¹¹, figure 7.
Similar letters indicate corresponding parts.
.
In these drawings, referring at present to Figures 1, 2 and 3, the letter
designates the frame of the motor and B is the main spring, arranged as usual and
provided with the usual means for winding. The first or great wheel c of the motor
is connected by a train of gear wheels, with a pinion D mounted loosely upon a post a
which is rigidly secured in the frame A. E is a spindle or shaft arranged in line
with the post a, which shaft can turn freely in, suitable bearings, one of which may
be directly in the end of the post and the other in the frame. This spindle or shaft
I shall hereafter term the main shaft E. and it is the member to which a uniform
impulse is imparted and from which power is transmitted directly or indirectly to
any mechanism or device, such for instance as to the feed rolls of a magnesium light,
or to the pendulum or regulator of a time piece.
.
To the pinion D is connected, so as to turn with the same, an arm F projecting
radially therefrom and provided at or near its ends with laterally projecting stops I'
and 2 which are arranged to be successively engaged by a stop 3 located at the end
of an arm Gaffixed to a rock-shaft. 7. H is the equalizing spring which at the
outset is place under a definite tension and which "I have shown in the form of
spiral spring, having its inner end attached to the main shaft E and its outer eu.
secured to a post on the winding arm F. On the main shaft is an eccentric
L

page_text: which engages with a bifurcated arm I projecting from the rock-shaft b, the vibrations
of said arm due to the rotation of the main shaft being transmitted to the stop-
bearing arm G.
Referring to figures 1 and 2, the stop 1 on the winding arm F is engaged by the
stop 3 of arm G and consequently is prevented from turning in the direction of
arrow 10, in which direction the force of the main spring B would normally impel it.
In the mean-time the equalizing spring being under tension, turns the main shaft in
the direction of arrow 10. When the eccentric 4 draws the arm I downwards, or in
the direction of arrow 11 figure 1, the stop 1 is released from stop 3 and the main
spring is free to act. The winding arm F under the impulse of the main spring is
rotated in the direction of arrow 10 until the stop 2 is engaged by the stop 3 (see
figure 4) which as here shown is one-half a rotation, and the equalizing spring is
wound up to correspond. When the main shaft has turned sufficiently to cause the
eccentric 4 to raise the arm, the stop 2 is released from stop 3 and the winding arm
completes the revolution. On inspection of figures 1 and 3, it will be noticed that
stop 1 is further removed from the centre of the arm F than stop 2, so that when the
arm G is in its highest position the upper edge of stop 3 will engage with the lower
edge of stop 1, and when in its lowest position, the lower edge of stop 3 will engage
the upper edge of stop 2.
The equalizing spring H is best made in the form of a spiral spring and in
practice I make use of a very long light-spring, which at the outset is placed under
à definite tension. This tension is sustained by the periodical rewinding to which the
spring is subjected. Instead of winding the spring periodically through half a turn
as illustrated, the winding arm and the stops could be arranged to coil the spring
periodically through one-quarter of a turn or less, but I have found that when a long
hair spring is used, no appreciable increase of tension follows the winding of the
spring through a half turn.
It will be noticed that the main shaft E rotates in the same direction as the spring
is wound, and that it turns through half a revolution before the rewinding of the
spring takes place, consequently the impulse on the shaft is constant at all times.
From the foregoing description it will be readily understood that the general
function of the equalizing spring is to transmit constantly to the main shaft a
definite impulse, regardless of the existing tension of the mainspring or other source
of power, the said equalizing spring being always wound to a definite extent and
always under the same tension.
The form of motor just described is especially adapted for magnesium lights where
a constant impulse is required for continuously feeding the ribbon along, the velocity
with which the rolls are turned being determined by any suitable timing device.
One form of timing device I have illustrated in figures 7 and 8 of the drawings
viz., an escapement and pendulum as ordinarily used in clocks, and I will now describe
the arrangement of my improvement in time pieces.
I will not at present enter into the construction of the clock movement here shown,
as my equalizing device can be applied to any well known movement. In Figures 7
and 8, E is the arbor of the scape wheel which arbor corresponds to the main
shaft of figures 1 and 2.
The inner end of the equalizing spring H is secured to said arbor as before, and the
pinion D carrying the arm F is connected with the train of wheels constituting the clock
movement and consequently is ultimately in connection with the centre wheel K
on the centre arbor N. The scape wheel J is engaged by an anchor L connected
with a pendulum M as usual. The action of the motor is the same as before, while
the stop 3 engages either of the stops 1-2 the train of wheels is held out of action,
but on release of either stop 1 or stop 2, it is free to move and to actuate the hands m
and of the clock.
As here shown the clock movement is released at every half revolution of the
scape wheel J, which is so geared that the hands are moved twice each minute,
through a space corresponding to one-half a minute on the dial, at each release of the
motor. In the case of clocks embodying a weight movement, the equalizing spring

page_text: counteracts any irregularities in the construction of the gears constituting the move-
ment and any variation in the friction thereof. The use of such powerful main
springs as my invention will permit of, would ordinarily involve the use of a crank
arm or its equivalent for winding the said springs. This I propose to avoid by
placing the winding arbor or arbors outside of the spring or springs.
:
In the example shown in figures 7 and 8 of the drawings, I employ a common
winding arbor O for both main-springs B¹ B¹ which is connected by trains of
gears cd-e, with the first or great wheels C¹ C¹, and by a third train f-g with
the centre arbor, said trains at the same time forming also a portion of the clock
train, and the trains c-d-e reducing the power required at the winding arbor.
./
The pinion of train c-d-e, is made fast to the winding arbor O, while the
gear wheel of train f-g is loose thereon and carries a detent i engaging a ratchet
wheel j fast on the arbor O, so that in winding up the springs, this wheelf will not
rotate.
The winding arbor may be similarly placed and connected when only one main
spring B is used in the clock movement, and it is evident that three or more main
springs could be geared together in the same manner.
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. In a clock movement an equalizing spring for the governing member and a
main spring for actuating the train, normally held out of action and released at
determinate intervals to rewind the equalizing spring and to actuate the movement,
substantially as described.
2. In a clock movement, a main spring for actuating the train, normally held out
of action, an equalizing spring for the governing member adapted to be coiled by said
main spring, and device actuated by the uncoiling of the equalizing spring to
release the main-spring, said, main-spring on its release recoiling the equalizing
spring and actuating the train, substantially as described.
3. In a clock movement, a stop for holding the main spring out of action, an
equalizing spring for the governing member, incorporated in said movement and a
device for releasing the main spring to coil the equalizing spring. and to actuate the
train, substantially as described.
4. In a clock movement, a timing device, an equalizing spring for the timing
device controlled thereby, a main spring for recoiling the equalizing spring at
determinate intervals and for actuating the train during such periods of recoiling, a
stop for the main-spring and a device actuated through the uncoiling of the equalizing
spring to release the main spring from the action of the stop, substantially as:
described.
5. In a clock movement a main-spring for actuating the train, normally held out:
of action, an equalizing spring for the governing member adapted to be coiled by
said main-spring through the intermediate train, and a device actuated by the
uncoiling of the equalizing spring to release the main-spring, said main-spring when
released recoiling the equalizing spring and actuating the movement during such
period of recoiling, substantially as described.
6. In a clock movement an equalizing mechanism incorporated in the train or
hand actuating mechanism and controlling the main spring, said main spring recoiling
the spring of the equalizing mechanism and actuating the said train during the period
of recoiling said spring, substantiaily as described.
7. The combination of a main spring, an equalizing spring, a winding arm
arranged to be actuated through an intermediate train by the main spring to coil
the equalizing spring, and suitable stopping and starting devices, substantially as
described.
8. The combination of a main-spring, an equalizing spring, a winding arm arranged
to be actuated through an intermediate train by the main-spring, an escapement for

page_text: controlling the uncoiling of the equalizing spring and suitable stopping and releasing
devices, substantially as described.
.. 9. The combination of a main spring, a revolvable shaft, a train of gear wheels
between the shaft and the main-spring, all constituting a motor, a winding device
carried by one of the gear wheels of the train, an equalizing spring having
one end attached to the shaft and the other to the winding device, a regulator or
governing member, a stop for holding the main spring out of action, and a releasing
device actuated at determinate intervals, substantially as described.
10. In a mechanical motor, the combination of the main spring, a main shaft, a
winding arm, a spring having its inner end attached to the main shaft and its
outer end to the winding arm, a tripping mechanism actuated by the main shaft,
and a gear connection between the main spring and the winding arm, substantially as
described.
11. The combination with the main spring and the main shaft of a winding arm
having two stops, a spring attached to the main shaft and to the winding arm, a stop
for successively engaging the stops on the winding arm, a cam or eccentric on the
main shaft for actuating the latter stop, and a connection between the main spring
and the winding arm for actuating the latter when released from the stop, substantially
as described.
12. An equalizing mechanism for spring motors, consisting of a revolvable shaft, a
winding arm arranged to turn about a centre in line with the shaft and provided
with two stops, an equalizing spring having one end attached to the revolvable shaft
and one to the winding arm, an arm provided with a stop adapted to engage with the
stops of the winding arm, a cam on the revolvable shaft, and an arm engaged by the
said cam,and connected with the stop bearing arm, substantially as described.
13. In a mechanical motor, the combination of a main spring, a winding arbor and
gears connecting the winding arbor with the spring gear, said gears forming a part
of the train of the motor, substantially as described.
14. In a mechanical motor, the combination of two or more main springs, a common
winding arbor, gears connecting the winding arbor to the spring gears, and a train
of gears connecting the winding arbor to the centre arbor, said gears forming a part
of the train of the motor, substantially as described.
15. In an equalizing mechanism for spring motors a revolvable shaft, an escapement
wheel mounted on said shaft, a winding device, a spring having one end attached to
the shaft and the other to the winding device, and a gear connected with the motor
and actuating the winding device, all said parts being arranged about one and the
same centre line or axis, substantially as described.
16. The combination with the frame A of a post secured in said frame, a shaft E
arranged in line with the post and having a bearing therein, a winding device F
mounted on the post, a spring H connected with the shaft and the winding device, a
stop, and a cam 4 engaging said stop, substantially as described.
Dated
101 1000
HENRY SMITH PRENTISS.
By Harris & Mills,
23, Southampton Buildings, London, Agents.