US2482061A

US2482061A - Master clock

Info

Publication number: US2482061A
Application number: US488189A
Authority: US
Inventors: Hamlin Marston Lovell
Original assignee: Individual
Current assignee: Individual
Priority date: 1943-05-24
Filing date: 1943-05-24
Publication date: 1949-09-13
Anticipated expiration: 1966-09-13

Description

Sept. 13, 1949. M. L. HAMLIN I 2 5 MASTER CLOCK Filed ma 24, 1943- 7' l s Sheets-Sheet 1 INVENTOK JV wm I kg v I F g fkmhm [Mu Sept. 13, 1949. M. 1.. HAMLIN 2,482,061

MASTER CLOCK Filed May 24, 1943 5 Sheets-Sheet 2 IN VENTOR.

Mm Lam/u JW M- L. HAMLIN MASTER CLOCK Sept. 13, 1949.

5 Sheets-Sheet 5 Filed May 24, 1943 Wy v INVENTOR.

p 3, 1949. M. L. HAMLIN 2,482,061

' MASTER CLOCK Filed May 24, 1945 5 Slieets-Sheet 4 IN VENTI'OR.

M. L. HAMLIN MASTER CLOCK Sept. 13, 1949.

5 Sheets-Sheet 5 Filed May 24, 1943 INVENTOR.

Patented Sept. 13, 1949 UNITED STATES PATE T-orifice MASTER CLOCK Marlton Lovell Hamlin, Lynbrook, N. Y. Application May 24, 1943, Serial No. 488,189

16 Claims.

This invention relates to a clock comprising an isochronously oscillating member which is undamped at the ends of its excursions and is maintained byshort, sharp, banked impulses at substantially the mid points of its excursions, and a counting mechanism which counts in suitable units the number of excursions of the oscillating member and whose action is controlled by said impulses independently of said oscillating member. More particularly the invention relates to a pendulum clock in which short, sharp, banked impulses are applied to the pendulum bob in phase with its swings, the pendulum being entirely free at the ends of its swings, and in which no energy for operating dial works or other counting mechanism is taken from or reacts on the pendulum.

It is one object of this invention to provide a commercial precision clock requiring a minimum of precision operations in its construction.

It is another object of this invention to provide a commercial precision clock containing few and simple moving parts.

It is another object of this invention to provide a clock whose timekeeping shall be in a high degree independent of the mechanical condition and state of lubrication of its works.

It is another object of this invention to provide a commercial precision clock to serve as a master clock or program clock or clock for the control of tower clocks, from which any desired number of signals or control impulses at desired intervals may be taken off without in any degree affecting the rate of the clock.

It is another object of this invention to provide a clock in which a. pendulum or other isochronously oscillating system receives a constant impulse of very short duration substantially at the mid point of its excursions and is free of interference at the ends of its excursions.

Other advantages will appear in the following description to those skilled in the art.

Hitherto it has generally been considered desirable in order to avoid disturbing vibrations to apply impulse to a pendulum or other oscillatin member used for timekeeping in the form of a gentle pressure of substantial duration, the pressure increasing gradually to a maximum and gradually decreasing during the impulse period. In some forms of escapement, e. g., in the recoil and Graham dead-beat anchor escapements and in the Grimthorpe gravity escapement, the impulse members act on or are acted on by the pendulum during all or the greater part of its swing. In others, e. g., in the Synchronome escapement, the impulse is confined to a fraction,

2 but a substantial fraction of the total swing. In all cases, however, the impulse involves a certain amount of rubbing or rolling friction between the pendulum and other parts of the mechanism for a sensible fraction of the pendulum swing.

I have found that this friction and relatively prolonged interference with the swing of the pendulum may be avoided without introducing undesirable distortions or vibrations of the pendulum by applying the impulse in the form of a light, practically instantaneous tap to an adequately heavy pendulum bob at or near the mid point of its swing. I have further found that by banking or limiting the fall of the impulse member at a fixed point I may make the impulse selfcompensating for minor variations in its velocity or force,.thereby maintaining the amplitude of the pendulum substantially constant.

In one embodiment of my invention an impulse is imparted to the bob of a seconds pendulum at every complete swing (i. e., every two seconds) at the center of its swing by a gravityor springloaded impulse member which is periodically released by a trigger pull on the pendulum acting on a, light trigger mounted on a detent which engages the impulse member. I have found it practical to have this release occur not more than 10'-15' of are from the center point of the swing when the half swing of the pendulum amounts to approximately 1 to 1 30' of arc; the duration of the release action is extremely short; the rest of the swing is free of interference except for the nearly instantaneous impulse tap at the center. This interference is not only small and of short duration, but substantially constant in phase and amount. These conditions, viz., minimum constant interference limited to the center portion of the pendulum swing, make for precise timekeeping. Furthermore since the impulse is applied to the bob rather than to the rod, it produces no perceptible distortion of the rod or undesirable vibration.

Several preferred embodiments of my invention are illustrated diagrammatically in the accompanying figures and are described below. but the invention is not intended to be limited thereby.

Figure 1 illustrates the pendulum unit of one embodiment of my invention as seen from the front.

Figure 2 is a section on the line 2-2 of Figure 9..

Figure 3 is a front view of certain details of the impulse and reset mechanism of Figure 1.

Figure 4 is a sectional view on line 4-4 (Figure 5) of a portion of the mechanism shown in Figures 3 and 5.

Figure is a front view of the impulse-member mounting.

Figure 615 a plan view of the electromagnet pole pieces and armature shown in elevation in Figure 3.

Figure 7 illustrates the back and Figure 8 the front of one form of counting mechanism.

Figure 9 is an elevation of a modified electric maintenance mechanism.

Figure 10 illustrates on method of taking period signals or impulses from a clock embodying this invention.

Figure 11 is a front elevation of a gravityor spring-operated maintenance device embodying my invention.

Figure 12 is a section on line I2-I2 of Figure 11 and indicates diagrammatically it relation to and dial works.

Figure 13 is an elevation and Figure 14 a plan in simplified diagrammatic form of a modified electric maintenance and counting system.

In the drawings the heavy line 1 represents the outline of a case which may be hung on a wall by hanger 2 screwed to an angle-iron bracket 3 inside the case. Two pieces of angle iron 4 are welded to bracket 3 to form a support for threaded stud 5 which turns freely in threaded holes in supports 4. A hook 8, firmly secured to stud I by nuts I, carries jams 8 between which thin steel suspension springs 9 are gripped by screws passing through holes in the springs. A bar l0 also carries jams similarly gripping the lower ends of springs 9.

Pendulum rod II, made of a low-expansion nickel-steel alloy. is threaded into bar I0 and locked by nut I2. Bob I3 has a hole passing through and perpendicular to its axis through which the lower threaded end of rod I I passes with a sliding fit. The bob is supported on the rod by rating nut I4, locked b nut I5. Number I0 and I1 indicate small shelves fixed on rod I I, on which rating weights may be placed. A pointer II on the lower end of the rod and scale I8 fixed to case indicate amplitude of pendulum swings.

A metal panel 20 carries the maintenance gear for keeping the pendulum swinging. At its righthand end it rests on fixed stud 2| against which it is held by spring 22. At its heavier left-hand end it is supported by adjusting nut 23 bearing on bracket 24' fixed to panel 20; nut 23 is threaded on low-expansion-alloy rod 24 which at its lower end passes through a hole in bracket 24' and at its upper end is fixed in bracket 3. Fixed studs 25 carry spring clips 26 which keep panel 20 in vertical alinement while permitting vertical adjustment by nut 23, and horizontal adjustment by means of jaws 21 and 28 engaging stud 2| and independently pivoted on stud 29 fixed in panel 20. Jaw 21 is pressed against stud 2| by tension spring 30, while jaw 28 is pressed against the other side of stud 2| by adjusting screw 3| threaded through a stud fixed in panel 20.

The impulse and reset gear i indicated in general at 40 in Figure 1 and shown in greater detail in Figures 3-6.

An impulse member 4|, pivoted at 42 on a twopart brass arbor, carries detent arm 43 engaging detent 44. On one part of arbor 42 is fixed the inner end of spring 45, the outer end of which is fixed to stud 46 adjustably mounted by an arm 47 on panel 20. Member 4| also carries cam 48 on its upper portion. Member 4| is adapted to engage anvil 4| carried by bob I3 when 4| is in its released p sition, but is high enough in its as the pendulum member 4| by screw II and is thereby grounded to panel 20 through spring 48 and arm 41 and their respective mountings which are of brass. Lead 84, which is still! enough to be self-supporting is electrically connected to the outer end of flexible spiral conductor 80, which is advantageously a ribbon of brass shim stock 0.001 inch thick. The spiral conductor at its inner end is connected with wire mount I! carried by brass plate 60 connected with lead I08.

Posts 60 mounted in panel 20 carry outer brass plate 63 in which outboard pivot 42 is mounted by means oi. adjustable bearing 04 threaded into the plane and locked by nut 52.

Brass plate 88 is mounted on Bakelite block 50 which is mounted on plate 63. Lead I03 is thus insulated from panel 20 which serves as ground. Part of outer plate 03 is omitted in Figure 3 for greater clarity.

Adjustable banking screw 6| threaded into stud 82 mounted on panel 20 limits the movement of impulse member 4| by contact with detent arm 42.

The impulse-reset mechanism comprises electromagnet I0 with coil 'II and pole pieces 12 adapted to attract armature 13. The latter is carried on a rocking member pivoted at 74 on an arbor supported between panel 20 and a front plante 80. This member consists of a central brass block I5 and four perpendicular arms 10 fixed in the block; three or these arms carry ad- Justable balancing and inertia weights I1. The lower arm I6 also carries a small stud I8 screwed into the arm perpendicular to the plane of the diagram and adapted to engage cam 48 when impulse member 4| is in its released position. Adjustable banking pins BI and I2 limit the rotation of the rocking member.

Electrical energy to operate the clock is provided by storage battery I00 (Figure 1), connected to the clock by leads IOI and I02. Lead I03 connects lead I0| with mercury switch 50; lead I04 is connected with magnet coil 'II- and with panel 20 to which the switch is grounded by lead 53, and thus connects the switch with magnet coil II A condenser I05 to suppress sparking in the switch 50 bridge leads I03 and I04. Lead I00 from magnet coil connects with lead I02 through variable resistanc I01.

Leads I08 and I0! connect leads I04 and I02, the latter through variable resistance IIO, with the counting mechanism of the clock, i. e., the dial works, described below and shown in Figures 7 and 8,

Impulse member 4| is maintained in the position shown by contact of arm 43 with detent 44. The latter is pivoted at 85 and the upper arm held as shown against banking pin by hair spring 81. A small face plate 80 supports the outer pivot and is carried by back plate 88' which supports the inner pivot. Plate 88' is adjustably mounted on panel 20 by screw 89.

The lower portion .of detent 44 carries trigger 80 pivoted on the detent at 9|. An upper projection of the trigger engages lower radial arm of the detent. The trigger is thus free to pivot in a clockwise direction, but on being moved In a counterclockwise direction it carries detent 44 aasaoar' with it. The trigger normally hangs in a vertical position as shown.

Horizontal rod 92 is adjustably mounted on rod Hand carries adjustably mounted trigger pull 93.

The various adjustments having been properly made, operation of the isochronous or pendulum unit of the clock is as follows:

Assume the pendulum set in motion manually and swinging from its center position to the left. Trigger pull 93 pushes aside trigger 90 and lets it fall without disturbing detent 44; the pendulum completes its excursion to the left undisturbed. On its return trigger pull 03 again engages trigger and moves it to the right. This time, however, the trigger carries the detent 44 with it by virtue of the engagement of the upper projection of the trigger with the lower radial arm of the detent, until the trigger falls of! the trigger pull and the detent is again forced back lightly against banking pin 86 by spring 81.

This movement of the detent releases arm 43, so that impulse member 4| falls towards anvil 4| urged by spring 45, and is stopped at the end of its motion by contact of arm 43 with banking screw 6|.

If pendulum is swinging with correct amplitude, impulse arm 4| strikes anvil 4| hor'zontally at center of pendulum swing, and at the same time arm 43 strikes banking screw 6|, If excursion of pendulum is too wide, its velocity at center of swing will be greater, so that it will have passed center point before impulse arm is arrested by banking screw; consequently arm 4| will not strike anvil 4| before pendulum passes center point and arm is arrested by banking screw. The pendulum thus receives no impulse and its amplitude is lessened. On the other hand if the excursions are too small, velocity will be less, and arm 4| will strike anvil 4| before pendulum passes center point. The spring 45 is adjusted to furnish slightly more impulse than is needed for maintaining the oscillations of the pendulum; consequently the ampltude of its swing will increase until the excess impulse energy is absorbed by pin 6|. Furthermore when the bob is moving faster, if struck by impulse arm it will absorb less energy. and when moving slower more energy from im ulse arm which always moves at the same rate.

As will be seen from the above, the pendulum w ll take just sufficient energy from impulse arm 4| to ma ntain its swings at substantially constant amplitude. or will average out small variations and thus avoid any cumulative error.

As impulse arm 4| falls and arm 43 swin s towards the hor zontal, mercury drop 5| rolls against electrodes 52 and closes the circuit to electromagnet co l 1| from battery I00 by leads |0|, I03. 54, 53. ground through panel, leads I04 and I06 through resistance I01 and lead I02 and auxiliary connections described.

On bein energized. magnet 10 sharply attracts armature 13. This results in stud 18 being thrown smartly against cam 48 with sufficient force, by virtue of the inertia of weights 11, to reset arm 43 on detent 44 (which after being pushed aside is restored to locking position by spring 81), while drop 5| rolls away from electrodes 52, thus opening the circuit. Lower rocker arm 16 falls back by gravity against banking pin 82 owing to the adjusted balance of weights 11, and the cycle is ready to be repeated.

It will be seen that the impulse supplied to the pendulum is substantially constant and entirely independent of current strength provided only that there is sufiicient current to operate. The impulse assembly (4|, 43, 48, 50). and the detent assembly (44, 00) are o'fvery light construction and springs 45 and 81 ar relatively weak, so that friction on pivots 42 an ,85 and between trigger pull 03 and trigger 90 is very small. Little change takes place in the operation of these units over extended periods of time. The impulse is independent of the mechanical condition and state of lubrication of most of the mechanism, i. e., of the reset mechanism above described and the counting mechanism described below, the only requirement being that they be in sufliciently good condition to operate.

The impulse arm may be gravity-loaded by appropriate weighting, and spring 45 may then be dispensed with.

For the most refined work pivots 42 and 85 may be mounted in jeweled bearings, trigger and/or trigger pull 03 may be jewelled and springs 45 and 81 may be made of Elinvar or similar alloy of low temperature-stiffness coefficient.

In the counting mechanism (Figures 7 and 8) three

hands

20l, 202 and 203 show respectively hours, minutes and seconds. They are of the jump type, i. e., the hour hand moves only at the end of each hour and then moves forward an hour interval on the dial, the minute hand moves similarly each minute and the'second hand each second. These hands are carried on arbors 20|', 202 and 203' pivoted in plate 204 and in bridge plates omitted from the drawings for clarity.

Each arbor carries fixed to it a toothed wheel,

respectively 205, 206 and 201. Wheel 205 has 24 teeth, and

wheels

206 and 201 60 teeth each. On each of the two latter wheels is fixed a

spiral cam

208 and 209.

A half-second compound pendulum 2|0 with upper and lower bobs is mounted on pivoted arbor 2 which carries fixed to it armature 2 I2. When the pendulum swings the armature swings alternately into line with and away from poles 2|3 of an electromagnet (shown partially cut away in the drawing) which is mounted to the rear of wheel 201 by means of posts screwed into plate 2 4.

A gathering pawl 2|4 is pivoted on armature 2|2. Its lo er end is adap ed to en a e the teeth of wheel 201. Pivoted at 2 IS on pawl 2|4 are two links 2" and 2|8. Slots in the outer ends of the links embrace fixed pins 2|9 and 220 so that the links are capable of a limited sliding and rotational motion on the pins. The lengths of the links and the positions of the pins are such that they permit pawl 2|4 to engage and gather one and only one tooth of wheel 201 at each com lete oscillation of pendulum 2|0 (when it oscillates through a sufficient angle). regardless of how great the amplitude is beyond the required minimum.

An electric impulse is transmitted once every two seconds by leads I08 and I09 to the coil 2|3 (shown partly cut away) of the electric magnet provided with pole pieces 2| 3, the periodicity being precisely controlled by the above described movements of the mercury switch 50, which is controlled in turn by the swings of pendulum ll, l3.

The bobs of pendulum 2|0 are adiusted to give it an approximate /z-SGCOIld rate (one complete swing each second) accordingly the electric impulses arriving at exactly two-second intervals energize pole pieces 2|3 at exact two-second intervals, thereby setting in oscillation the compound pendulum 2|0 and maintaining it in am- 7 chronism with but at twice the rate of the main pendulum ll, [3. The inertia of the bobs of pendulum 2!0 is suflicient to keep it swinging eight or ten times even if the electric impulses should be temporarily discontinued.

Since the /2-second pendulum makes a complete swing each second, the attached gathering pawl 2|4 advances wheel 201 one tooth or /60 revolution each second, and accordingly associated hand 203 indicates seconds on its dial (Figure 8). Spring-tensioned pawl 22!, bearing on the teeth of wheel 201 prevents overrunning and retrograde movements of the wheel.

The left end of rocker arm 225 (viewing Figure 7) pivoted at 226 is pressed lightly against cam 209 by spring 221, which draws up the left end of rocker arm 228 against stud 229 on the right end of rocker arm 225. Rocker arm 228 is pivoted at 230; at its right end it carries springtensioned pawl 23! which engages teeth of the minute wheel 206; it also carries fixed stop 232 which engages the teeth of wheel 205 and prevents overrunning of the wheel on completion of a downward stroke of this end of the rocker arm.

As wheel 201 is rotated, cam 209 raises the left end of rocker arm 225 and depresses its right end. Stud 229 accordingly depresses the left end and raises the right end of rocker arm 228. As wheel 201 rotates hand 203 to the 60-second point, arm 225 falls off the end of cam 208, and spring 221 rocks arm 228, depressing pawl 23! and advancing minute wheel 206. The lift of cam 209 and the lengths of

arms

225 and 228 are so chosen that pawl 23! gathers one and only one tooth of wheel 206 in each cycle of operation of the rocker arms. Accordingly hand 202 is advanced one minute on its dial each time hand 203 reaches the 60-second mark. Spring-tensioned pawl 233 bearing on the teeth of wheel 206 prevents retrograde movement of the wheel.

Similarly the rotation of wheel 206 and spiral cam 206 advances wheel 205 by means of rocker arms 235 and 238, pivoted at 236 and 231, tension spring 239 and spring-tensloned pawl 240 engaging the teeth of hour wheel 205. In this case, however, the lift of cam 208 and the lengths of the arms 235 and 238 are so chosen as to advance wheel 205 &4 revolution each cycle. Accordingly associated hand indicates hours on its 24-hour,

dial. Spring-tensioned pawl 24! bearing on the teeth of wheel 205 prevents overrunning and retrograde movement of the wheel.

The embodiment illustrated in Figure 9 is in general similar to the embodiment illustrated in Figures 3 and 6, but differs from the latter chiefly in that the reset lever (a) is balanced to reset the impulse member by gravity after each impulse, (b) is released to do this by the contact of a corn on the impulse member with a detent lever, and (c) is restored to its raised position by an eiectromagnet. The magnet is controlled by a mercury switch operated by a forked arm on an extension of the reset lever. Instead of a mercury switch various types of mechanical switch can be used.

This form of the invention has more moving parts than that shown in Figure 3 but has the advantage that the impulse member, having no mercury switch and thus being considerably lighter in weight, acquires greater angular acceleration from a comparatively weak spring. This lessens the interval between trigger pull and impulse and brings the trigger pull proportionately nearer the center swing.

In the drawing for the sake of simplicity and clarity certain details identical with those in Figure 3 have been omitted. Identical parts in Figures 3 and 9 are indicated by identical reference characters and have the same functions in both embodiments.

Construction and operation of this escapement are as follows: Trigger pull 93, trigger and detent 44 function as in Figure 3. Impulse memher 340 differs from impulse member of Figure 3 in carrying no switch and in having a cam 348 differently located from cam 48; it is pivoted at 42 between plate 363, mounted on studs 60 and metal panel 20. Detent lever 34! is pivoted at 342 between plate 343 and panel 20; its lower arm is heavier than its upper and consequently it normally rests on stop 344. At its lower end lever 34! carries a short perpendicular pin 345 projecting into the plane of cam 348. At its upper end lever 34! engages projection 313 on body 315 of reset lever.

The reset lever, pivoted at 14, is weighted by weight 311 on arm 16 so that, when released, it tends to rotate clockwise till stopped by banking pin 382.

The lower portion of body 315 carries curved arm 310 in a plane parallel to panel 20 but on the opposite side of impulse member 340 from the panel. At its lower end it carries pin 319 extending perpendicularly towards pane into the plane of impulse member 340.

At the upper portion of body 315 are affixed armature 13 (constructed and functioning as in Figure 3) 'and extension arm 316 with fork 318 at its upper end adjusted to operate mercury switch 350 as described below.

Switch 350 contains a drop of mercury 35! adapted to close the circuit between two electrodes 352 when the electrode end of the switch is depressed. The switch is carried in a clip pivoted at 355 between panel 20 and a small plate 356; the latter carries brackets with limit screws point of the pendulum 351 threaded in them to adjustably control extent of movement of the switch. Rigidly fixed to the switch clip is arm 353 carrying perpendicularly fixed pin 354 positioned to be engaged by arms of fork 318. The electrodes 352 are respectively connected to extremely

flexible leads

303 and 304, e. g., helical ribbons of 0.001 inch brass shim stock. Lead 304 is grounded to panel 20, to which lead !04 is connected, while lead 303 is connected to lead I03 at post I03 insulated from panel 20.

When arm 43 is released and arm 4! delivers its impulse to anvil 4! (as described in connection with Figure 3), cam 348 strikes pin 345 thus rotating lever 34! slightly clockwise and disengag ing its upper end from projection 319 On body of reset lever. This permits the reset lever to rotate clockwise on its axis 14 under influence of weight 311, thereby bringing pin 319 into contact with the upper part of impulse arm 4!. This forces entire impulse member 340 to rotate clockwise and resets arm 43 on detent 44 as described in connection with Figure 3. Simultaneously upper arm 316 moves to the right, bringing the left finger of fork 318 into contact with pin 354 on arm 353 of switch clip and rotating switch 350 counterclockwise sufficiently to cause mercury drop to roll to electrode end of switch. Reset lever comes to rest when arm 16 strikes banking pin 382.

Contact of mercury with the electrodes closes circuit with battery I through electromagnet coil II by means of leads IOI, I03, 303, 304, I04, I00, I02 and auxiliary connections described. Energizing of magnet I0 in this way attracts armature I3, thus rotating reset lever counterclockwise on its axis I4 until projection has risen past top of detent lever 34I. Banking pin 38I limits rotation in this direction by contact with arm I5. Simultaneously the right arm of fork 318 strikes pin 354, rotating switch 350 clockwise to position shown in the figure, thereby opening circuit to magnet coil II. The reset lever being freed of the attraction of the magnet, falls back slightly till held by contact of projection 319 on end of detent lever 3, as shown in Figure 9.

The distances, inertias and magnetic attraction are made such that the time required for this cycle of operations is only a small fraction of that needed for a complete swing of pendulum II, I3. Accordingly the impulse mechanism is in postion to repeat the cycle at each swing of the pendulum, and oscillations of the pendulum are thereby maintained.

A counting mechanism or dial works of desired design is "connected in parallel with 0011 'II by leads I08 and I09 as illustrated in Figure 1, and thereby indicates time as previously'described. The dial works may advantageously have the form shown in Figures 7 and 8.

Alternatively by suitable changes in magnet coils and resistances in well known ways, the counting mechanism may be connected in series with coil II.

When it is desired to use the clock of this invention for transmitting periodic signals, a separate battery or other source of electric current I000 (Figure 10) may be provided, connected by one lead with a suitable signal or electrical impulse transmitter IO0I. Arbors such as MI, 202' and 203 of the dial works, electrically insulated from each other, carry respectively contact arms I20I, I202 and I203, adapted on rotation of the arbors to make contact with adjustably fixed spring contact arms I2II, I2I2 and I2I3. Transmitter IO0I is connected by a lead and wiping contact with arbor 20I. Spring contact arm I2 is similarly connected with arbor 202 and spring arm I2I2 with arbor 203. Spring arm I2I3 is connected by the other battery lead with battery I000. The three contacts, the battery and the transmitter are thus connected in series. As the contact arms mounted on the arbors 20I' 202' and 203' rotate in the direction of the arrows they periodically make contact with the spring arms I2II, I2I2 and I2I3, arm I20I once in 24 hours for 1 hour, arm I202 once an hour for 1 minute, and arm I203 once a minute for 1 second. Since all contacts must be closed to transmit a signal, the arrangement described will transmit a signal of l seconds duration once every 24 hours. In the diagram this will occur at OO OO OO to 00 00 0l By suitably altering the position of fixed arms I2II, I2I2 and I2I3 angularly around the respective arbors, the time at which the signal occurs may be altered at will in one-second steps.

If only a momentary signal is desired arm I2 I3 may be adjusted so that arm I203 contacts it only between two second stations, e. g., between 14 and 15 seconds.

Signals at other intervals may be transmitted by similar arrangements in ways readily understood by those skilled in the art. For example, by short-circuitin the contact on the 24-hour arbor 20l', the arrangement shown will transmit one-second signals once an hour; by doing this and also providing four spring contact arms electrically connected in parallel and spaced apart around hour arbor 202, one-second signals will be given every 15 seconds. An almost unlimited variety of signals, both as to duration and timing, is thus possible by using suitable connections and contacts.

The signals or electrical impulses thus lsent may be used to operate lights or bells, to control process cycles, actuate or control machinery, tower clocks, secondary clocks and the like by suitable relays, amplifiers or other devices well known to the art.

The important feature that these various methods and means of signal transmission have in common is that, in contradistinction to many previously suggested signaling methods, those described have no effect on the running rate of the clock. This is because, as pointed out above, the operation of the dial works or counting mechanism does not in any way react on the operation of the pendulum, regardless of the particular type of counting mechanism used or the particular form or motive power chosen within the scope of my invention.

Figure 11, a cut-away front view, and Figure 12, a side view partly in section, represent another embodiment of my invention in which a pendulum is maintained in oscillation and its swings counted by mechanical instead of electrical means.

In these figures II is the pendulum rod, I3 the bob, and H the anvil; 20 is the panel supporting the maintaining gear 400. Trigger-pull 93 is adiustably fixed on rod 92 mounted adjustably on rod I I. Detent 44 pivoted at 85, banking pin 86, spring 81 and trigger 90 pivoted on detent 44 at 9I function as in the first described embodiment.

A weighted impulse member 0 is mounted on arbor 420 pivoted between face plate 40I and back plate 402. Face plate 40I, of the same size and shape as back plate 402, is omitted in Figure 11 for clarity. Detent arm 430 is formed integral with member 4I0, as is reset arm 480. In the position shown detent arm 430 engages detent 44, holding member 0 in a raised position above the path of swing of anvil 4'I and bob I3.

An escape wheel IE0 is mounted on arbor I40 pivoted between plates 40I and 402. The latter are held in spaced relationship to each other and also mounted on panel 20 by posts 403. Escape wheel I60 carries three radial teeth I6I and three rearwardly extending pins 162. On rotation of the escape wheel the teeth in turn engage one end of detent 500 pivoted at 50I; the other and heavier end of the detent carries adjusting screw I00 adapted to engage detent arm 430 when the latter is released by detent 44. Banking pins 502 and 503 limit the movement of detent 500. Pins 162 are adapted to engage arm 480 when detent arm is released and when escape wheel revolves.

Arbor also carries fixed on it bevel gear 80I meshing with bevel gear 802 fixed on vertical shaft 803; the latter is rotatably mounted in brackets 804. Shaft 803 is connected, as by a universal joint, with shaft 806. The latter is connected with any suitable type of conventional clockwork, dial, hands, etc., indicated at 806,, to which power is continuously applied by spring, weight or other means. The direction of rotation impressed on the clockwork by this means is such as to force escape wheel 160, as seen in Figure 11, in a counterclockwise direction. The gear ratios are such that the hands oi the clockwork are advanced six seconds for each full revolution of escape wheel 160. The clockwork and its connections are of conventional type well understood by those skilled in the art and require no further description.

The operation of this mechanism is as follows: When the pendulum swings to the left (viewing Figure 11) after being set manually in motion, trigger pull 93 raises and drops trigger 90 with out moving detent ll, as described in connection with Figure 3. On the return swing the trigger pull momentarily pulls aside trigger 80 and detent 44, releasing detent arm 430. This permits weighted impulse arm to fall, striking anvil 4i and imparting an impulse to bob i3, the timing being so adjusted that this occurs at the center of the swing. The weight on arm 0 is chosen so as to furnish slightly more energy on striking anvil ll than is required to maintain the oscillations of the pendulum. The fall of member 0 causes arm 430 to rise and strike adjusting screw 109, raising it and depressing opposite end of detent m. This action of the detent releases escape wheel 160, which rotates counterclockwise, being propelled by the force transmitted through gears 80! and 802 and shafts I03 and 806 from the above-mentioned clockwork.

Rotation of the wheel brings one of the pins 162 to bear on arm 480 and forces it to the right, thereby raising weighted member "0 again to the position shown in Figure and resetting arm 0 on detent 44. As arm 430 is forced down, screw 100 falls, thus raising the opposite end of detent 500 which engages the next tooth of the escape wheel and arrests its rotation.

From this description it will be seen that on each full swing of the pendulum, its bob receives an impulse from member ill, and escape wheel 160 rotates one third or a turn, at the same time resetting the impulse member. Since the pendulum is a seconds pendulum, this cycle occurs every two seconds and wheel 160 completes a rotation every six seconds. Accordingly the hands of the clockwork referred to above, which advance six seconds with each revolution of wheel I60, indicate correct time intervals.

The banking eilfect of pin 502 through detent I" and screw 100 on arm 430 operates to lessen or prevent an impulse being imparted by member l0 to anvil II in case the pendulum is momentarily swinging too wide so that its angular velocity at the center of its swing is greater than normal. This absence of or reduction in the impulse soon reduces the amplitude of the pendulum swing. On the other hand if the pendulum is not swinging wide enough, the angular velocity of the bob is less at the center of the swing, and member 0 strikes anvil Ii slightly earlier in the swing; this lengthens the duration of the impulse and increases the amplitude of the pendulum. Furthermore the faster the bob moves the less energy, and the slower it moves the more energy it absorbs from the impulse member, which always falls at a constant rate. These actions are similar to those described in connection with the first embodiment and similarly tend to keep the arc of swing of the pendulum constant.

Another embodiment of my invention is illustrated diagrammatically in Figures 13 and 14. In this embodiment the pendulum is entirely free of mechanical contact with the maintaining gear except for the nearly instantaneous tap of the imi2 pulse arm- Ill every two seconds on anvil I at the exact center of the pendulum swing.

The lower end of rod I I is provided with a lightweight opaque screen pierced by a slot "I. The screen intercepts light beam 903 from lamp "2 which is focussed on three photoelectric cells 8, III! and I. As the pendulum swings. however. slot "I permits beam "3 momentarily to illuminate the three photoelectric cells in turn. Consider a swing from left to right. Cell Ill is first energized by the beam; current passes through it and is amplified by amplifier "1, which may be of any suitable commercially available type and is powered by current source "8; current passes through lead electromagnet coil Ill and return lead ill. The coil Sill is part of a relatively slow-acting relay and when it is energized the magnet attracts pivoted armature Ill, causing it to close the gap between its end and spring contact SIB. Owing to the slow action of this relay, this gap remains closed while slot Ill illuminates cell a fraction of asecond later, causing current to pass through lead Ill, electromagnet coil 8, lead lit, contact SIB, armature III, and return lead Ill. Magnet 9 attracts armature I" forming upper radial arm of detent 9 pivoted at 0. This releases detent arm 8", integral with gravity-loaded impulse arm llll and return cam I", pivoted at 820, so that impulse member falls and arm llll strikes anvil 4|, thereby maintaining the swing of the pendulum as described in connection with first-disclosed embodiment; in the present embodiment also banking screw 6| functions, by contact with arm "I, to limit drop of impulse member and thus keep the swings of pendulum II, II substantially constant. Positions of slot "I, lamp III and cell 805 are so adjusted that the impulse occurs at the center of the pendulum swing.

As the swing of the pendulum continues, relay Ill-llB-Sli opens, cells "I and "I are darkened and detent 8 is returned to its original position by a spring not shown.

Finally slot "I illuminates cell "I, which is so located that this occurs at the extreme right of the pendulum swing. Current then flows through lead 9", electromagnet coil H and return lead Oil. Energizing coil II causes magnet Ill to attract armature 13, thus rocking associated reset lever pivoted at 14 and resetting detent arm 830 on detent 9 by contact of stud 18 with reset cam I80.

On the return swing, when cell It! is illuminated, no current passes through magnet coil 9, since gap between armature m and contact ill is open. Accordingly impulse member is released only on left-to-right swings of the pendulum.

The counting mechanism associated with a pendulum of this type may be operated in numerous ways, for example by a circuit I0! and II! in parallel with coil 6, or by an independent circuit and photoelectric cell.

A pendulum of this type absorbs only sufficient energy to overcome the friction of passage through air and of the flexing of its suspension springs and gives up no appreciable energy in releasing the impulse mechanism; it is advantageously operated in a constant-temperature and constant-pressure container or case.

It will be seen that in all the embodiments of my invention described above an isochronously oscillating member is kept oscillating by almost instantaneous impulses imparted to it substantially at the mid point of its excursions by an impulse member whose impulse strokes are banked or limited by a fixed stop so positioned that abnormally wide excursions of the oscillating member partly or entirely escape the normal impact of the impulse member. In this way abnormally wide oscillations quickly diminish to normal amplitude. Abnormally short excursions of the oscillating member are increased by reason of the resulting longer time of contact of the impulse member with the oscillating member; furthermore I prefer to reinforce this action by providing a slightly more energetic impulse than is required to maintain normal oscillations, the excess energy being absorbed by impact of the impulse member with the fixed stop.

A counting or time-indicating mechanism is preferably associated with the impulse member in such a way that its indications are controlled solely by the action of the impulse member but in strict synchronism with the oscillating member. Thus no. energy is absorbed by the counting mechanism from the oscillating member nor does the former react on the latter. Accordingly the isochronism of the oscillating member is not disturbed by the functioning of the counting or time-indicating mechanism.

While it is desirable from the viewpoint of consistent timekeeping to limit any necessary in terference with an isochronously oscillating membere. g., release of-impulse member and impulse-to positions as close as possible to the mid point of the oscillations, some deviation from this practise is possible for many purposes without serious practical disadvantage. The chief requisite is to keep the oscillating member free of interference at the-ends of its oscillations, but it is further preferable to confine such interference to the central portion of the oscillations. For example, in the embodiments shown in Figures 3 and 9 adjustments may be made so that the impulse occurs at substantially the mid point of the pendulum swing and the release occurs a necessary fraction of the are before the impulse, or so that the release and impulse occur on opposite sides of the mid point of the swing. For many purposes good results are had if the impulse occurs not more than A the half swing away from the mid point; in the claims I have used the phrase "at approximately the mid point in this sense.

I claim:

1. A clock comprising an isochronously oscillating pendulum having a bob, an anvil fixedly associated with the pendulum at a point not remote from the bob and having an impact face normal to the path of travel of the bob, an impulse member adapted to deliver an impact of only substantially instantaneous duration to the impact face of said anvil at approximately the mid point of the oscillations of the pendulum when the impulse member is released from a biased position, a detent adapted to retain the impulse member in its biased position, a trigger on the detent adapted to release the impulse member by displacement of the detent when moved in one direction but free to move in the other direction without action on the detent, a trigger-pull mounted on the pendulum adapted to engage the trigger, a banking stop adapted to limit the impulse stroke of the impulse member in fixed relation to the oscillations of the pendulum, a powered reset means adapted when operated to contact the impulse member in its released position and reset it to its biased position, means associated with the impulse member to cause the reset means to operate after each release of the impulse member. and powered time-indicating means controlled by the action of the impulse member to indicate time in synchronism with but without reaction on the pendulum.

2. A clock as defined in claim 1 in which the reset means and the time-indicating means are elcctromagnetically powered, a source of electric current, leads connecting the current source in circuit with the reset means and the time-indicating means, a common switch controlling passage of current to the reset means and time-indicating means, said switch being responsive to the action of the impulse member.

3. A clock as defined in claim 2 in which the reset means and the time-indicating means are electromagnetically powered and controlled by a common oscillatory mercury switch having an operating angle independent of the angle of swing of the pendulum, said switch being pivotally mounted on fixed bearings and operated by a pivoted arm responsive to the action of the impulse member.

4. A clock as defined in claim 2 in which the impulse member is an oscillating member and the reset means and time-indicating means are electromagnetically powered and controlled by a common mercury switch mounted on and oscillating with the impulse member.

5. A clock as defined in claim 1 in which the reset means comprises an escape wheel having an element adapted to engage the impulse member when released from its biased position and on rotation of the escape wheel to reset the impulse member to its biased position, and in which mechanical operating means connects said escape wheel with the time indicating means, whereby rotation of the escape wheel is accompanied by actuation of the time-indicating means.

6. A program clock comprising an isochronously oscillating pendulum, an impulse member adapted to deliver an impact of only substantially instantaneous duration to a point on on near the bob of said pendulum at approximately the mid point of its oscillations when the impulse member is released from a biased position, a detent adapted to retain the impulse member in its biased position, a trigger on the detent adapted to release the impulse member by displacement' of the detent when moved in one direction but free to move in the other direction without action on the detent, a trigger-pull mounted on the pendulum adapted to engage the trigger, a banking stop adapted to limit the impulse stroke of the impulse member in fixed relation to the oscillations of the pendulum, a powered reset means adapted when operated to contact the impulse member'in its released position and reset it to its biased position, means associated with the impulse member to cause the reset means to operate after each release of the impulse member, powered time-indicating means controlled by action of the impulse member to indicate time in synchronism with but without reaction on the pendulum, said time-indicating means having at least one arbor rotating in timed relation to but without reaction on the oscillations of the pendulum, and signal means actuated by rotation of the arbor.

7. A combination comprising a pendulum having a bob, means for maintaining oscillations of the pendulum solely by delivering successive substantially instantaneous impacts to an impact face of the bob at an intermediate point not remote from the mid point of its oscillations, said impact face being a plane surface normal to the path of travel of the bob, means responsive to travel of said pendulum at an intermediate point in its oscillations for effecting operation of said impact delivering means, whereby said pendulum is free of interference at the ends of its oscillations, and means responsive to movement of said impact-delivering means for restoring said impact-delivering means to condition for delivering another impact to said bob during a subsequent oscillation of said pendulum.

8. The combination comprising a pendulum having a bob adapted to swing in a predetermined path, an impact-delivering member pivoted to swing in another path, the path of said pendulum bob at an intermediate point of its swing intersecting the path of said member, means responsive to movement of said pendulum at an intermediate point of its swing for effecting actuation of said member to deliver an impact of only substantially instantaneous duration to said bob at an intermediate point of its swing and means responsive to movement of said member for restoring it to a position out of the path of said bob for delivering another impact to said bob.

9. A clock comprising a pendulum with 9. bob, a pivoted impulse member adapted to deliver from a biased position an impact of only substantially instantaneous duration to said bob at approximately the mid point of its swings, a movable detent member including a trigger adapted to retain said impulse member in its biased position, said trigger being movably mounted on said detent and adapted only when pulled in one direction to move said detent to release said impulse member, a trigger-pull on said pendulum adapted to move said trigger in its operative direction at a point in the pendulum swing not further removed from the center of swing than about the half swing, a mercury switch mounted to swing with the impulse member and close a circuit when the member is in its released position, a banking stop positioned to limit the impact movement of the 'impulse member in fixed relation to the pendulum swings, a pivoted reset lever adapted when operated to reset the impuse member to its biased position, inertia weights on said reset lever balanced to urge said lever to a non-operative position, an armature on said reset lever, an electromagnet adapted when energized to attract said armature and thereby bring the reset lever into operative position to reset said impulse member to its biased position, an electromagnetically operated time-indicating means, a source of electric current, and electric leads connecting said source with said mercury switch, said electromagnet and said time-indicating means, whereby after each operation of said impulse member it is reset to its biased position and the time-indicating means operates in synchronism with but without reacting on the pendulum.

10. A clock comprising a pendulum with a bob, a pivoted impulse member adapted to deliver from the biased position an impact of only substantially instantaneous duration to said bob at approximately the mid point of its swings, a movable detent member including a trigger adapted to retain said impulse member in its biased position, said trigger being movably mounted on said detent and adapted only when pulled in one direction to move said detent to release said impulse member, a trigger-pull on said pendulum adapted to move said trigger in its operative direction at a point' in the pendulum swing not further removed from the center of swing than about A the half swing, a banking stop positioned to limit the impact movement of the impulse member in fixed relation to the pendulum swings, a pivoted reset lever adapted when operated to reset the impulse member to its biased position, biasing means associated with said reset lever to urge it to an operative position, a retaining means on said reset lever, a detent lever adapted to engage the retaining means on the reset lever to hold the reset lever in non-operative biased position, means on the impulse member adapted when the impulse member is in released position to disengage said detent lever from said retaining means thereby releasing the reset lever to move to an operative position and reset the impulse member to a biased position, an armature on the reset lever adapted when attracted to move the reset lever to a biased position in which it is retained by the detent lever, an electromagnet adapted when energized to attract said armature thereby moving it to its biased position, an electric switch, an arm on said reset lever adapted to open said switch when the reset lever is in biased position and close it when the reset lever is in operative position, a source of efectric current, an electromagnetically operated time-indicating means and electric leads connecting said source with said switch, said electromagnet and said time-indicating means, whereby after each operation of said impulse member it is reset to its biased position and the time-indicating means operates in synchronism with but without reacting on the pendulum.

11. A clock comprising a pendulum with 8. bob, a pivoted impulse member adapted to deliver from a biased position an impact of only substantially instantaneous duration to said bob at approximately the mid point of its swings, a movable detent member including a trigger adapted to retan said impulse member in its biased position, said trigger being movably mounted on said detent and adapted only when puled in one direction to move said detent to release said impulse member, a trigger-pull on said pendulum adapted to move said trigger in its operative direction at a point intermediate the ends of the swings of the pendulum, an escape wheel provided with detaining and reset means, the reset means being adapted on rotation of the wheel to engage the impulse member in its released position and move it to its biased position, a detent lever adapted in its equilibrium position to engage said detaining means and prevent rotation 'of the escape wheel and adapted to be rium position by movement of the impulse member to its released position thereby permitting rotation of the escape wheel, banking means adapted to limit movement of the detent lever and the impulse member, powered time-indicating means, and mechanical means connecting the time-indicating means with the escape wheel and reversibly applying torque to the latter, whereby the powered time-indicating means furnishes energy for maintaining the oscillations of the pendulum and is controlled in its indications to synchronize with but not react on the oscillations of the pendulum.

12. A combination comprising an isochronously oscillating pendulum, impulse means adapted to deliver an impact of only substantially instantaneous duration to a point not remote from the bob of the pendulum at an intermediate point in its oscillations, means responsive to oscillations of the pendulum for effecting operation of the impulse means without reaction on the pendulum at the ends of its oscillations, and means for removed from its equilibstoring the impulse means to condition for delivering another impact to the pendulum.

13. A clock comprising an isochronously oscillating pendulum, maintaining gear, and timewhich a banking stop is provided to engage the impulse member at the instant of impact to cause the impact to occur at a desired intermediate point in the swing of the pendulum and to preindicating means; said maintaining gear comprisvent prolongation of the contact between the iming an impulse member adapted to maintain the pulse member and the bob. oscillations of said pendulum solely by delivering 16. In combination, a pendulum having a bob, aseries of timed substantially instantaneous horia bell crank lever pivoted adjacent the path of zontally directed impacts to the bob of the said bob, one arm of said bell crank lever being pendulum at an intermediate point in its osciladapted to impart instantaneous impacts to said lations when the impulse member is released from bob, a detent member including a trigger engaga biased position, a detent adapted to retain the ing the other arm of said bell crank lever to impulse member in its biased position and periodimaintain the impact arm out of the path of movecally to release it from its biased position in rement of the bob during movement of the pendu-. sponse to the travel of the pendulum, a banklum in one direction, said trigger being movably ing stop adapted to limit the impulse stroke of the mounted on said detent, a trigger pull on said impulse member in fixed relation to the oscillapendulum, said trigger pull engaging said trigger tions of the pendulum, and powered reset means when the pendulum is moving in said one direcfor restoring the impulse member to its biase tion without releasing said detent from said other position after each impact, said maintaining gear :0 arm but upon movement of said pendulum in being without reaction on the pendulum at the the reverse direction, said trigger pull operating ends of its oscillations; and said time-indicating said trigger to release said detent from said other means comprising counting means responsive to arm to impart an instantaneous impact to said the action of said maintaining gear but without pe u b y the impact arm 0f Said l ti on said impulse member or said crank lever, and means for restoring the bell pendulum. crank lever to its original position with the im- 14. In combination, a pendulum having a bob, pact arm out of the path of movement of the an impulse member having an impact portion bob. and a detent portion, a detent member including MARSTON LOVELL HAMLIN. a trigger engaging said detent portion to maintain the impact portion out of the path of the REFERENCES CITED pendulum during movement of the pendulum in 7 one direction, said trigger being movably mounted i ififizf gf are or record m the on said detent and adapted to engage a portion of the pendulum during its movement in said di-' 85 UNITED STATES PATENTS rection without efieeting release of said detent N b r Name Date portion by said detent but adapted upon move- 205,303 Pratt July 9, 1878 ment of the endulum in the reverse direction 1,043,917 Fery Nov. 12, 1912 to engage said portion of the pendulum to efiect 1,564,303 Warren Dec. 8, 1925 refease of said detent portion by said detent to 1,743,231 Packard Jan. 14, 1930 cause said impact portion to impart a substan- 2,033,899 Poole Mar. 10, 1936 tially instantaneous impact to the pendulum bob, and means for restoring the impulse member FOREIGN PATENTS and the detent to a position such that said impact Number Country Date portion is maintained out 01' the path or said 919 Great Britain Jan. 14, 1908 P m- 160,204 Great Britain Mar. 17, 1921 15. A combination as defined in claim 14, in 233,828 Great Britain May 21, 1925 Certificate of Correction Patent No. 2,482,061

September 13, 1949 MARSTON LOVELL HAMLIN It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows:

Column 3, line 18, for the words an d dial? read the dial; column 4, line 22, for

lumn 7, line '61, for "com "plane read plate; line 36, for plante read late; 00 read cam; column 14, line 42, for on near rea or near;

and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Oflice. Signed and sealed this 13th day of June, A. D. 1950.

THOMAS i3" ME RPHY 5i eats up"; i ommzssm