US55731A - Improvement in valve-gear for steam-engines - Google Patents

Description

UNITED STATES PATENT OFFICE.

EDWIN SPRAGU, OF ALLEGHENY, PENNSYLVANIA.

IMPROVEMENT IN VALVE-GEAR FOR STEAM-ENGINES.

Specification forming part of Letters Patent No. 55.73 l, dated June 19, ISGS.

To all whom fit may concern:

Be it known that I, EDWIN SPRAGUE, of the city and count-yof Allegheny', in the State of Pennsylvania, have invent-ad a new and useful Improvement in 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 use of an adjustable point in connection with a cam, cam-yoke, cam-rod, and hinged lifters on the rocking shaft, which lifters are. held in their working position by means of triggers which are operated by means ofinclined planes, said adjustable point, cam, canryoke, canrrod, hinged lifters, triggers, and inclined planes being used in connection with the valveAlevers of steanrengines for the purposel of opening` the steam valves or ports and closing them at any desired point in the stroke of the engine,

ythe wholebeingconstructed, arranged, and operating in the manner hereinafter described.

To enable others skilled in the art to make and use myinvention, l will proceed to describe its construction and operation.

In theaccompanying drawings, Figure 1 represents a side elevation of an exigirlefurnished with my improvement for operating the valves. Fig. 2 represents a plan or top view ofthe same. Fig. 3 represents the side pipe, and also represents the hinged lifters, triggers, inclined planes, and the relation these parts bear to the lever to which the valve-stems are attached. Fig. 4 represents a top view or plan ofthe in clined planes, their guide, and the lever for operating them. A

In thedrawings, Arepresents the base or bed for the engine. B represents the cylinder. C represents the side pipe. e represents the standards which act as the fulcrum for the levers fi, to which the stems g of the valves are attached. 6 represents the piston. It represents the Thead, to which the pitman, marked 7 is attached. 9 represents the crank, which is secured on the end of the shaft 16. 15 re p resents the cam-yoke. 14 represents the guides for the cam yoke. 5 represents the slides for the T-head R. 10, 11, and 12 represent the cam-rod, which is attached to the cani-yoke 15.

8 represents the rock-shaft, on the end of which is placed the shifting-lever, marked j, which is furnished with wrists, marked lc and l.

All of the parts above mentioned are of ordinary construction, and theirarrangeinent and use are well understood. I will therefore proceed to describe the parts which constitute my invention and their relation to the parts as above mentioned.

The cam marked 1S is secured on the shaft 16, and is what is termed a full-stroke77 cam. This cam is furnished with a slot, marked 20. Ou the. shaft 16 is also placed what I shall term an adjustable point.77 This pointis marked 17, and is arranged on the shaft I6, in close contact with the cam 1S, and is so arranged on the shaft 1G and with relation to the cam that it can be secured to the cam 1S at any' point desired by means of a set-screw, which can be moved back and forward in the slot 2() of the cam 1S.

19 represents a spring which is used for holding the canryoke 15 in contact with the cam 1S and the adjustable. point 17. The arrangement of this spring will readily be seen by a reference to Fig. 1. in the, drawings, and it will readily he observed by the skillful mecha-nic that other arrangements of spring or other device can be substituted for holding the camyoke in contact with the cam and point.

On the rock-shaft S is secured a piece, marked p, to which. are secured lifters, marked a, which are hinged at the point marked c. To lthe piece markedp are also secured two triggers, marked r, which have two arms each. One of these arms on each of the triggers connects with the lower arm of the lifters n, and the other arms act on the inclined planes marked 1.

The form and arrangement of the lifters u, triggers r,'and inclined planes '1, and the relation that theyT bear to each other, are clearly shown in Fig. 3. The inclined planes marked 1 are se' cured on a plate, marked y, which moves in a guide plate, marked 4, or between guides, marked el, as shown in Figs. 3 and 4. These guides 4 are secured on the side pipe, C, and are so arranged with relation to the plate y as to bring the inclined planes directly under the lower arms of the triggers r. To the plate y is attached a lever, marked o, which is secured to the side pipe, O, and has its fulcrum at 0. The leyero is furnished with an index-pointer,

marked t, which is used in connection with a scale, marked a0, to show at what point the steam is cut off'.

The lever ois used when a number ofinclined planes of different heights are used, so that the cut-oft may be used in connection with the governor ot' engines, as indicated by the parts marked fw, which is attached to the governor so that it can move up and down with the rise and fall ot' the governor-balls. Thepart marked 'L0 moves in guides, as indicated by the parts marked 22, and the lower part of the part w is furnished with a slot, marked 21, which runs obliquely to the plane ot' the part marked w. In this slot is placed the point marked 2 of the lever o. Now, every ehangein the position oft-he governor-balls will change the position of the plate y, and thereby bring a different inclined plane under the lower arms ot' the triggers o",

and thereby cause a difference in time of the triggers holding the litters a in a lifting position. It will be observed that but two inclined planes are represented in the drawin gs-one for each trigger; but, as already stated, a number of these inclines may be placed side by side, so that each trigger shall have a series ot' inclines and all made operative through lever 0 and plate y.

The lever o, in connection with the plate y, is also used for the purpose ot giving the engine full stroke. This is accomplished by so moving the lever o and plate y that the lower arms of the triggers r will not come in Contact with the inclined planes 1.

The reverse action or motion is given to the engine by unshipping the cam-rod from oft' wrist Zand shipping it ou the wrist k.

The cam-rod can be made in one or more parts, as desired, and its length adjusted by any of the known means. In the drawings the cam-rod is represented in three parts-to wit, 10, 11, and 12-and the parts 11 and 12 attaehed to an upright, marked 13, which will have a vibrating motion when the engine is working. The cam-rod is represented as being adjusted by means of a set-screw, marked Q2, which mode of adjustment will readily be understood by reference to Fig. 1.

The operation of my improvement is as follows: I set the adjustable point 17 on the cam 18, so as to get the desired stroke of the camrod which will give the desired movements to the lever j and rock-shaft 8, which will move the piece p, which will cause the lifters n to come in Contact with the levers i, which will lift the valves and admit steam to the cylinder; and the lower arms of the triggers will come in contact with the inclines marked l, which will cause the triggers to unship and let the litters drop down on the pieces marked 3, which will close the valves by the dropping of levers fi. As one of the triggers r becomes unshipped the other becomes shipped. The steam is exhausted in the ordinary manner.

Having thus described my invention, what I claim is- 1. The hinged litters n, said lifters being operated by mea-ns ot' triggers r and inclines l, or their equivalents, and one cam-rod made in one or more parts, said litters, triggers, inclines, and cam-rod being dependent for their action upon the cam 18 and adjustable point 17, substantially as herein described and set forth.

2. The adjustable point 17,when used in com; bination with a cam and cam-yoke and a single cam-rod for working a full stroke, and used for operating the cut-oft' gear of steam-engines, as herein described and set forth.

3. rIhe inclines 1 on plate y, said plate and inclines being operated by lever o through the medium ot' a governor or otherwise, substantially as herein described, and for the purpose set forth.

EDWIN SPRAGUE. Witnesses:

JAMES J. JOHNSTON, ALEXANDER HAYs.

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