US23684A - Alexander l - Google Patents

Description

STATES PATENT OFFICE.

' ALEXANDER L. HOLLEY, OF NEW7 YORK, N. Y.

VARIABLE CUT-OFF GEAR FOR STEAM-ENGINES.

Specification of Letters Patent No. 23,684, dated April 19', -1859.

To all whom 'it 'may concern:

Be it known that I, ALEXANDER L. I-IOLLEY, of the State, county, and city of New York, have invented a new and Improved Method of Eecting a Variable Cut-Off for Steam-Engines; and I do hereby declare that the following is a full and exact description thereof, reference being had to the accompanying drawings and to the letters of reference marked thereon.

The nature of my invention consists in the combination of the motion of an eccentric, with the motion of a supplementary steam piston, to produce such a motion of the main valve, as shall rapidly open the induction end of said valve, with any desirable lead, and close the same and instantly at any desirable portion of the stroke of the main piston, without closing the exhaust end of said valve till the main piston has nearly completed its stroke.

The accompanying drawings Figures 1 and 2 show the application of the above valve motion to the ordinary locomotive engine, Fig. 1 being a plan, and Fig. 2 a side elevation.

The same letters refer to like parts.

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

The eccentric rod D from the eccentric A moves the lower arm of the lever E F by the hook G. To reverse the engine, the hook H on the same eccentric rod D is connected with the pin F of the lever E F by means of the reverse shaft I, in the ordinary manner.

The lever E F is attached to and moves the rock shaft J, which moves the lever K, which moves the lower end of the lever L M. The supplementary steam piston B is attached by its rod Q to the lever L M at N, and the valve stem O of the main valve C is attached to the same lever at M. The eccentric rod D, may if convenient be attached directly to the lever L M at L, thus dispensing with the lever E F and the rock shaft J. Also, a separate eccentric may be used for reversing. Also the valve stem O may be arranged to take hold of the lever L M below the piston rod Q, and still perform the same functions. It is here attached above the rod Q to give the piston B a short stroke, thus avoiding its slamming o by great momentum.

The motion of the piston B may be arrested at the end of its stroke by any of the ordinary methods. It is here arrested by the disks R S which are secured to the piston rod Q) coming in contact with the rubber disks c c. The commencement of the motion of the piston B is accelerated, and the close of its motion is retarded by the springs T U.

Steam is admitted to the piston B by the ordinary valve motion, consisting of the valve c, valve rod f, rock shaft g eccentric rod L and eccentric z'. The eccentric z' may be turned forward or backward on the main shaft V to vary the time of the opening of the valve c, and hence the time of the cut-o of the main valve C by any of the ordinary methods, or the valve c may be driven by tappets from the cross head W. The eccentric z' is here moved forward and backward as follows viz: The eccentric z' is secured lto and turns with the gear wheel 7c which is revolved on the shaft V by the gear wheels m n, which are turned by the gear wheel 0, which isy secured to, and turns with the shaft V.

The ring p which is loose on the shaft V holds the wheels m n in their places. The ring p, being moved forward or backward by the rod g and the lever r, it moves the wheel 7c and the eccentric z' backward or forward, thus varying the time of the opening of the valve c. works the supplementary valve of the other main steam engine of the locomotive, is fastened to and wo-rked by the same wheels lc m n 0.

The operation of the engine is as follows, viz: The piston P standing at the back end of its stroke as shown in the drawing, the valve C is set with the desirable lead. The piston P moving forward, the lower end of the lever L M moves backward, and the upper end of L M moves forward, opening the valve G. At any point during the stroke of P, at which the small valve c shall have been set to open, steam entering the port u drives the piston B back, which moves the valve C over the port o, but (in cutting olf y late in the stroke), does not close the exhaust port fw, which port is closed near the end of the stroke by the motion of the eccentric A. If the port w is closed, as it will be at the time of a cut o occurring early in the stroke, it is immediately reopened and held open till near the end of the stroke by the motion of the eccentric A.

The eccentric s which- The closing of the exhaust port, however, during the cut-off at any point, may be prevented by a wider opening of the cavity of the valve C at the cost of a slightly premature exhaust.

The simple motion of a steam piston, or any motion derived from the motion of the main steam engine, cannot be so applied to a valve as to enable it to perform the above functions, without considerable complication of parts; also, the motion of a steam piston applied instead of an eccentric for opening a rapidly moving valve, may not open said valve so exactly as to time, as to preserve a uniform lead. A slight variation in the cut off however, should such variation occur is of no practical account.

The advantages of this improvement are, lst. The ports are entirely opened before the valve cuts olf at any portion of the stroke of the piston, which prevents wiredrawing and waste of steam by friction. 2d. The cut-o of the steam is instantaneous, which prevents wire-drawing. 3d. A cutoif may be obtained at each point of the stroke f the piston. 4th. An injurious amount of compression or cushioning of steam Vis prevented. 5th. Premature exhaust is prevented. 6th. Since the lead is given to the valve by the supplementary piston, no lead is required on the eccentric, and hence one eccentric may be used for the forward and backward motion of the engine. 7th. The large parts of the valve motion are simple in construction and few in number, which will prevent undue repair expenses.

I disclaim the method described of moving the supplementary valve e, the same being in use.

I disclaim the use of a supplement-ary steam piston as the sole mover of a valve.

I claim- Such a combination of the motion of an eccentric or its equivalent, with the motion of a steam piston for moving a valve, as will effect a variable cut olf of the induction steam, without interfering with a free exhaust, substantially in the manner hereinbefore described.

ALEXANDER L. HOLLEY.

JOSEPH A. KENT, S. D. CoZzENs.

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