US359649A - Valve-reversing mechanism - Google Patents

Description

(No Model.) K I W'. L. TO'BEY. VALVE REVERS-ING MEGHANISM. No. 359,649. Patented Mar. 22, 1887.

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UNITED STATES PATENT GFFIC' WILLIAM L.l rroBnY, or BosroN, 'MAssAcHUsnrra VALVE'=REVERSING NIECHANISIVI.

SPECIFICATION forming part of Letters Patent No. 359.649, dated March 22l 1887.

Application tiled July 23, 1886. Serial No. 208.841.

To all whom it may concern:

Beit known that I, WILLIAM L. ToBnY, of Boston, 'county of Suffolk, and State of Massachusetts, have invented an Improvement in Valve-ReversingY Mechanisms, of which the following description, in connection with the accompanying drawings, isaspeciflcation, like letters on the drawings representinglike parts.

This invention has for its object to provide steam-engines with a valve-motion to take the place of the link-motion now commonly used to reverse the rotation of the crank-shaft.

My valve-motion is an improvement upon the valve-motion known to engineers as the Marshall or Hackworth valve-revers ing gearing, and has for its primary object to obtain equal opening and closing of the valve at each end of the stroke of the piston with equal points of cut-0H', my improved valvegearing being simple in construction and easy of adjustment. v

My invention consists, essentially, of a valve and valve-stem, andan eccentric-rod, a point in which moves in a path oblique to the length of the said eccentric-rod, combined with a lever fulcrumed to the said eccentric-rod, and having one end connected to the valve-stem and its other end moving in afixed path, substantially as will be hereinafter described.v

Figure 1, in section and elevation, shows a sufficient portion of a steam-engine to enable my invention to be understood; Figs. 2 and 3, diagrams showing different positions occupied by my improved valve-gearing to pro- `duce reverse rotations of the crank-shaft, and Figs. 4 and 5 details to be referred to.

The cylinder A, piston a, provided with the usual piston-rod, a, the valvechest A, and valve a", contained therein and having the valve-rod a3, are and may be of common construction, they being herein shown as constituting part oi' an upright engine.

The valve-chest A', as shown, is provided with the steam-inlet a.13 and the ports ct* af" and exhaust-ontlets as, the latter being at the ends of the said valve-chest. The lpiston-rod a is joined by a connecting-rod, b, to a crank, b', on a crank-shaft, b2. The crankshaft bz has mounted on it an eccentric, b3, provided with an eccentric-rod, b4, to which a link, 126, is pivoted at a point intermediate of the ends ofthe (No model.)

said eccentric-rod, as at b5, the other end of the link b being pivoted, as at bi, to a reversing-lever, c, pivotally secured, as at c', to a xed portion of the engine, the said lever being adaptedto be turned on its pivot from the position Fig. l to the positions shown in Figs. 2 and 3, to reverse the movement of the valve a2 and thereby the rotation of the crank-shaft.

The parts thus far enumerated are the same as in the Marshall valve-reversing gearing, and also' the same as the Hackworth, except in the latter the point b5 is a block pivoted to the eccentric-rod, the said block moving in a slide attached to the reversing-lever c; but in both the said `contrivances the valvestem is connected by a valverod to the end of the eccentric-rod.

The Marshall gearing is objectionable, as it gives unequal opening at the top and bottom of thev cylinder, and in order to secure equalv openings to the cylinder it has been necessary to double-port the cylinder at one end.

The excessive friction created by the use oi' the slides in the Haekworth gearing renders the said gearing impracticable.

In accordance with my invention, I obviate the objections due to the use of the double ports at one end of the cylinder, as in the Marshall valve-gearing, and I overcome the excessive friction common to the Hackworth gearing by means of a lever, B, which, in accordance with my invention, is fulcrumed near its center, as at d, to the end, as herein shown, of the eccentric-rod b.

The lever B has one of its ends, as shown at dx, connected by the valve-rod d to the valvestem a3, and has its other end suspended, as at d2, to an equalizing-link, d3, pivoted to aiixed portion of the engine; but, instead of pivoting the lever B to the pivoted link Lt-he said lever may be pivoted in a'block, d5, moving in asta- 'tionary slide, d6. (See Fig. 4.) The equaliz'inglink d gives to the point of the lever B where the latter is connected to the valve-rod substantially equal oscillation above and below the center, thereby securing substantially equal opening and closing of the valve at both ends of the stroke of the piston.

When the reversing-lever c occupies the central position shown in Fig. 1, the fulcrum b5 of t-he eccentric-rod b4 moves in a substan- IOC tially horizontal path, as showvn in Fie. 5 hy full linef. \Vith the reversingdever c thrown into the position Fig. 2, the path of movement of the fulerum b5 s indicated bythe dotted 5 1inef,:1nd when the reversing-lever c is thrown in the position shown in Fig. 3 to reverse the movement of the valves, and thereby the romtion ofthe crank-shaft, the path of movement of the fulermn b5 is indicated by the dotted iinef.

It will be noticed that thepnth of movement of the fnlerum If is in :rn oblique direction to the length ofthe eccentric-rod when the reversing-lever c is on either side of its central 15 position.

I einim- In n steam valve-motion, a valve and valvestem, and an eccentric-rod, n point in which moves in a path oblique to the length of the said eccentric-rod, combined with a lever fulerumed to the said eccentric-rod, and having one end connected to the Valve-Stem und its other end moving in a. xed path, substantially as and for the purpose set forth.

In testimony whereofI have signed my name to this specification in the presence of two subscribing witnesses.

ViLLTAM L. TOBEY.

YVitnesses:

G. W. GREGORY, J. H. CHURoHILL.

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