US194744A - Improvement in watch-escapements - Google Patents

Description

J. THOMSON.

WATCH-ESCAPEMENTS.

No- 194,744. Patented Aug. 28,1877.

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I UNITED STATES PATENT OFFICE.

JOHL THOMSON, OF ROCHESTER, NEW YORK.

IMPROVEMENT IN WATCH-ESCAPEMENTS.

Specification forming part of Letters Patent N 0. [94,744, dated August 28, 1877 application filed March 29, 1877.

time-pieces.

The balance-wheel of a watch, like the pendulum of a clock, is the device which measures or divides the time as indicated by the hands and dial, and upon the accuracy of the actuation of said balance-wheel depends its perfect performance.

In watches and similar time-keepers as heretofore constructed the balance-wheel receives its impulses from the escape-wheel through the medium of the escapement-lever directly, and hence is subject to all the irregularities dependent upon imperfections in the main gearing of the watch, or resulting from changes of temperature, or the decomposition of the lubricant and collection of dirt upon the parts. Or, in other words, the balance-wheel, instead of controlling the power, is controlled by it, and thus holds a secondary position, so to speak, instead of the first. For this reason a watch, in order to keep correct time, must be finely constructed in every particular, and even when most perfectly constructed it cannot be relied upon for more than three or four months, as a general rule.

The object of my invention is to overcome these defects, and produce a watch or other time-keeper that will run with regularity despite inaccuracies or imperfections of workmanship, change of temperature, or the decomposition of the oil or collection of dirt; and to this end my invention consists in imparting the impulses to the balance-wheel by an independent impulse-spring, set in motion by the escapement-wheel, but acting by its own tension to actuate the balance-wheel, whereby a regular and uniform motion will be transmitted to said balance-wheel entirely independent of the irregularities of the main works of the watch, as more fully hereinafter described.

In the drawings, Figure 1 is a top or plan view of my invention; Fig. 2, a side elevation;

and Fig. 3 is a detached view of the rollerjournal and lever.

The letter A represents the balance, and 12 its roller-jewel, constructed in the usual manner, and (l the escape-wheel, which is constructed in the usual manner, with the exception that it is provided with a series of projections or pins, 0, on one side, corresponding in number to its teeth, for the purpose to be hereinafter explained. The letter D represents the lever, the pallets E of which straddle the teeth of the escape-wheel, as usual. The working of the pallet-faces e e is substantially the same as that in common use; but the lever-fork d is quite different, being two or three times wider than the ordinary. Following the motion of the balance, as indicated 7 by the arrow, the roller-jewel b will enter the fork, carrying the lever with it, until the escape-wheel tooth is relieved at the pallet c. As the tooth passes over the pallet-face it will force the lever D forward in the same direction as the movement of the balance. It is this forward movement that gives to the balance of an ordinary lever-watch its momentum; but in this case the lever-fork is made so wide that no impetus whatever is given with this action, the pallet 0 being simply set forward sufficiently to receive another tooth of the escape-wheel, and the fork placed in the best position for receiving the rollerjewel on its return vibration.

The operation j ust described, having relieved the, escapewheel tooth at 0, allows the escapewheel to come forward to the pallet e. The manner in which the balance-wheel receives its momentum will now be seen. The im pulse-spring R, pallet K, andarm F may be in one piece, but are shown as separate and connected together. As shown, one of the projections or pins 0 on the balance-wheel has depressed the spring by coming in contact with the pallet-face K, holding it in tension until the forward movement of the escapewheel deprives it of its support, whereupon it comes sharply forward, and the stroke end of the arm F, coming in contact with the rollerjewel b, gives to the balance its momentum.

Upon the return vibration of the balance the escape-wheel will be again released, and the impulse-spring again depressed into acting position, when the operation first described will be repeated.

In order to have perfect control of the 1110-- tor of the balance, and to do away with ever having to alter the fine hair-spring, I place at the base of the impu'lse'spring a fine tensionspring, m, passing through a guideway, n, and moved back and forth, as the case may require, by the screw S.

Upon turning the screw to the right, the grooved head will force the spring through the guideway, adding power to the stroke or theimpulse-spring. Upon reversing the screw the power is decreased.

It is evident that with the above-described escapement I can produce a fine time-keeping watch at a low price. All that is necessary is a common quality of train-work and mainspring and a finely-adjusted balance and hairspring.

In the matter of regulation, the balance deriving its sole movement from the impulsespring, the first strike is the same as the last, and, being entirely outside of the fluctuations of the'mainor first power, must run uniformly for a long time.

With this escapement it will be practicable to make watches of long-runnin g time, and requiring winding but once in a week or longer. It may also be applied to clocks, but, requiring some different arrangement of details, will form the subject of separate applications for Letters Patent.

I do not intend to limit my invention to the precise details hereinbefore described, as modifications may be made embodying the same principle.

It will be observed that in this escapement the train-work is stopped when the balance is receiving its impulse, and in action only when the balance is entirely free of the impulsator and lever.

What I claim, and desire to secure by Letters Patent, is

1. Incombination with the balance-wheel of a watch or other time-keeper, an impulse device operated by the escape-wheel, but acting independently of the same and the escape-lever to impart the impulse to the balance-wheel, whereby a regular and uniform motion is imparted to said wheel.

2. In combination with the escape-wheel and the balance-wheel of a watch escapement, the adjustable spring R, its pallet K, and extension F, whereby the impulses are imparted to the balance-wheel, substantially as set forth.

3. The combination of the balancewheel A, the lever D, the escape-wheel O, and the impulse device F K R, the whole arranged to operate substantially as set forth.

4. In combination with the spring R, the spring m and screw S, for adjusting the tension of the spring R, substantially as and for the purpose specified.

JOHN THOMSON.

Witnesses:

JOHN MGKEE, JULIUS B. FRASER.

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