US237808A - bunnell - Google Patents

Description

(maal.)

J. H. B ELL.. Tele 'graf Keyl A No. 237,808. Patentd Feb.15,1s81.

N, PETERS. PMOTO-LITHOGRAPMER, WASHIGTON, D. 2A

UNITED STATES JESSE H. BUNNELL, OF NEW YORK, N. Y.

TELEGRAPHIC KEY.

SPECIFICATION forming part of Letters Patent No. 237,808, dated February 15, 1881.

' Appnonied october 15,1880. (Model.)

. To all whom it may concern:

Be it known that l, JESSE II. BUNNELL, a citizen of the United States, residing at New York, in the county and State of New York, have invented certa-in new and useful Improvements in Telegraphic Keys; and I do hereby declare the following to be a full, clear, and exact description thereof, reference being had to the accompanying drawings.

My invention relates more especially to that class of keys which are employed for the purpose of closing and breaking an electric circuit with rapidity and convenience in the transmission of telegraphic signals according tothe Morse or otheranalogous system of telegraph y.

My invention consists, iirst, in an improved telegraphic-keylever possessing the following characteristics: First, the key-leverand thel trunnions on which it oscillates are formed entire trom a slnglepiece ot' wrought metal; second, the key-lever is constructed of al breadth much greater than its depth or vertical thick-y ness. By this mode of construction the keyis rendered at the same time light and strong,it is better adapted to resist late-ral tlexure, and can be manipulated more rapidly than keys of the construction'heretofore used, while at the same time its durability is greatly increased.

The form of telegraphic key which has heretofore been found preferable for general use consists of a horizontal beam or lever having a slight vertical oscillatory movement upon a transverse axis securedthereto, which axis terminates in pivots or trunnious turning in suitable bearings. 4In keys of this construct-ion the horizontal beam or lever is made of cast metal, usually brass, while the transverse axis is of wrought-steel, the latter bein g made separately and afterward inserted into the bra-ss lever at right angles thereto. Suitable contact-points and adjustable stops, together witha knob lor button'for the convenient manipulation ofthe key-lever, are afterward afiixed thereto ina manner well understood.

lVith a key constructed in the manner just described it has not been found possible to secure sufficient lateral rigidity in the lever and its axls without increasing the weight ofmetal in the lever to a degree which renders the key co cumbersome to allow of rapid manipulaion. 1

In the operation of transmitting telegraphic signals the operator is required to oscillate the lever of the key upon its axis in a vertical direction at the rate of ten or fifteen, or 'even more, movements per second. Itis therefore highly important that the vertical play of the key-lever between its limiting-stops should be reduced to the least possible amount, and also of equal importance that the lever itself should be made of as little weight as possible. lf, however, the play of the key is made too small, any lateral motion of thecoutact-points causes them to fail to break the circuit with certainty when separatedan effect which is -technically termed sticking, and `which interferes materially with the correct and speedy transmission of signals. I have found that in the absence of any lateral motion between the contacts the play of the key may be made very much smaller than would otherwise be possible without injurious results. I have also found that thelateral motion between the contact-points which gives rise to the difficulty referred to is itself caused partly by the working of the 4key-lever upon its transverse axis and partly by the springing or tlexure of the axis itself when formed in the usual manner from a cylindrical rod ofsteel. In my invention both these sources of dit'iiculty are completely overcome, and I am enabled to construct a keylever possessing much greater lateral rigidity thau those hitherto iu use, while at the same time its weight is very much less.

ln the accompanying drawings, Figure 1 is a side elevation of a key embodying my improvements, and Fig. 2 is a plan view of the same. Fig. 3 shows the blank punched from s olidmetal, from which the key-lever and its axis are formed, and Fig. 4 shows the same in its completed state. Fig. 5 shows the transverse axis in elevation,-and Fig. 6 is a inodication in the construction of the bearings of the lever.

In the drawings, A represents the base or frame of the key, which may be of brass or other suitable metal, having upright standards a a formed upon it, which support adjustable setscrews a' a. rlhese set-screws constitute bearings upon which the key-lever B oseillates Vertically, its downward motion being limited by the contact-point c on the key-lever striking upon a similar point, c, mounted upon the base A, but insulated therefrom. Its upward motion is limited by an adjustable stop, C, by means of which the vertical play of the key-1ever B may be made greater or less, at pleasure. B is a knob or button by which the operator takes hold of the key in order to manipulate it. All these several parts are old and well known, and forni no part ot' my present invention, which relates solely to the particular construction of the key-lever B and its axis, as hereinafter described.

In constructing the lever B according to my improved method, l first punch a blank ot substantially the form shown in Fi by means of suitable dies, from a solid plate of metal of sufficient thickness to atiiord the requisite vertical stiness. l preferto make the lever B of steel, as thismaterial gives the greatest amount of strength with the least weight ot' metal; but nevertheless I do not propose to coniine myself to the use of any particular material. The blank thus prepared is shown iu Fig. 3, and is in the general form ot' a cross whose longitudinal portion B has a thickness-as seen, for example, in Figs. l and -considerably less than its breadth, as seen in Fig. 3, and a transverse portion, b b, of similar proportions, the latter being` designed to support the trunnions ofthe key. l prefer to form the longitudinal portion ot' the lever with lateral enlargements, as seen at f and g in Figs. 4 and 5, in order to form seats for the check-nuts of the adjustingscrews C and C', the former of which regulates the vertical play of the key-lever and the latter the tension ot' the reactin gsprinfr, both ot' which are the same as in keys ot' the usual construction. A similar enlargement may be i'orxned at c, to provide a bearingfor the knob B', it' desired. lly this mode ot' construction the amount of metal in the key, and consequently its weight, may be reduced without impair-ing its elliciency. Gylilr dric'al or conical trunnions or pivots b b are then formed upon the endsof the transverse portions I) b ot' the lever by means oi a lathe or otherwise, as shown in Fig. Ll, together with the necessary apertures for securin g the knob B', the adjusting-screw C, the contact-point c,

&c. The lever, with its attachments, is then mounted between the adjustable setscrews a a upon the base A, in the usual manner, said setscrews being, ot' course, provided with a conical recess or bearing in their ends for receiving the pivots b b.

A moditication ot the method of forming the bearings is shown in Fig. 6, in which the pivots are formed upon the points of the set-screws a a, and corresponding conical rcccsses are provided in the ends ot' the trans verse arms of the lever; but I consider this form less advantageous than the one hereinbefore described,

1t will be observed that the form of my improved key-lever is such as to give it great lateral rigidity, the thickness of the metal in the direction required to resist lateral exure being greatest at the intersection ot' the lougitudinal and transverse' portions of the lever, which is the weakest point in a key constructed in the ordinary manner. So, also, the process ot' forming the blank by punching it from a solid piece et' metal not only produces a much more rigid lever than the ordinary method of casting, even when the same metal is used, but also renders it possible to construct the entire lever ot' light and strong lnaterial-such as steel-which does not admit ot' being melted and cast in the i'orm required to produce a keylever ofthe form herein shown and described, and which could not therefore be successfully employedibr that purpose. l

v l claim as my invention- A telegraphic key-lever constructed, Substantially as hereinbefore set forth, from asingle pieeeof wrought metal in thei'orm of a cross, ot' a breadth greater than its depth or vertical thickness, and provided with trunnions formed upon the extremities of the transverse arms ot' the cross.

In testimony whereot' I have hereunto subscribed my name this 13th day of October, A. D. 188i).

JESSE H. BUNNELL.

Witnesses:

NELSON ZABRisKrE, MILLER O. EARL.

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