US11963A - Valve-gear foe - Google Patents

Description

UNITED STATES PATENT OFFICE.

JAMES FREELAND, OF ALLEGHENY, PENNSYLVANIA.

VALVE-GEAR FOR LOCOMOTIVEENGINES.

Specicaton of Letters Patent No. 11,963, dated November 21, 1854.

To all whom 'it may concern Be it known that I, JAMES FREELAND, of the city and county of Allegheny and State of Pennsylvania, have invented a new and Improved Valve-Gear for Locomotives and other Steam-Engines, in which the Slide- Valve is Employed for Controllingthe Induction and Eduction of Steam; and I do hereby declare that the following is a full, clear, and exact description of the same, reference being had to the accompanying drawings, forming part of this specification, in which- Figure l, is a side view of my improved valve gear, and Fig. 2, is a diagram illustrative of its operation.

Similar letters of reference indicate corresponding parts in both figures.

This invention consists in a certain combination of mechanism for transmitting motion from the eccentric commonly employed, to the slide valve, in such a manner that the whole or the greater part of the movement of the valve may be performed during a very small portion of t-he revolution of the eccentric, whereby the full width of opening may be given to the steam and exhaust ports by the time the piston has made a very small portion of its stroke.

To enable those skilled in the art to make and use my invention, I will proceed to describe its construction and operation.

A, is a rockshaft carrying the arm B, to which the eccentric rod is to be connected.

C, is anotherrockshaft parallel with and at a short distance from A, carrying the arm D, to which the valve rod is to be connected.

E, is a fixed pivot upon which a rocker F, is hung to vibrate freely.

G, is a lever connected at one end with the arm B, by a pivot a, which forms its fulcrum. The opposite end of the lever carries a pin fitted to work in a boX H, which is fitted to slide in a slot I, in the valve arm D. This slot I, is of the form of an arc described with a radius shorter than the arm, say about half the length, but this is not arbitrary. The lever G, is suspended at C, near the middle of its length by a link J, which is connected by a pin d, with the lower arm of the rocker Fthe upper arm of which is connected at the point e, by a link K, with a pin f, on the arm B. The distance between e, and f, is the same as that between a, and o, and the points d, and e, are equidistant from E.

The throw of thev eccentric in the valve gear represented, is supposed to be suiicient to move the arm B, to and from the positions indicated in dotted and blue outlines in Fig. 2. This movement causes the link K, to move the rocker E, to and from the positions indicated by lines of similar character, and to raise and lower the lever G, in the slot I, of the valve arm D. It also causes the valve arm D, to receive a rocking motion to and from the positions shown in black and red outlines; but the whole perceptible movement of the valve arm is produced during the time occupied by the arm B, and other parts of the mechanism are moving from about the position shown in red to that shown in black outlines, and during the movement of the arm B, from the position indicated by the blue to that indicated by the red outline, and from the position indicated by the black to that indicated by the dotted outline, and vice versa, no perceptible movement of the valve arm D, is produced. During the first described part of the movement to and from the black and red positions, the raising and lowering of the lever G, is hardly perceptible, and the box A, is nearly stationary in the arc formed slot I, of the arm D, so that`the lever acts as a connecting rod between the arms B, and D, and transmits a nearly equal movement from one to the other, but during the other parts of the movement, the lever G, has a very considerable rising and falling motion, and the box H, works up and down in the slot I, in such a manner that its effective length as a connection between B and D, is gradually increased and diminished, so as to compensate almost exactly for the movement of the point of connection a, and hencegives no perceptible movement to the valve arm D. It will be understood by reference to the diagram that the movement of the valve is effected while the eccentric and arm BV, are passing half stroke when their movement is the quickest, and this contributes in a great degree to the rapid opening and closing of the valve.

By varying the length of the lower arm E, d, or the rocker, the time occupied by the motion of the valve relatively to the time occupied by the revolution of the engine may be varied, the said length requiring to be shortened to give a slower'- motion, and lengthened to give a quicker motion to the valve.

What I vclaim as my invention,VV de;

sire to secu're by Letters Patent, is 2'- The employment, for the purpose of transmitting motion from the eccentric or its equivalent to the slide valve, of a rock shaft A, carrying the eccentric arm B, Which is connected with the valve arm Don the usualvalve shaft C, by means of'a connecting lever G, an arc formed slot I, a rocker Rand linksJ, K, all arranged,combined and operating substantially as lherein described, to give thervalve the Whole or the greater part ofits movement during a comparatively small portion of the revolution of the eccentric o1." its equivalent.

v Y' y lJAMES FREELAND. Witnesses:

S. BfW. GILL, JOI-IN CHnss-` A, l

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