Untitled record

Application filed June 8, 1881. (No model.)

To all whom it may concern:

Be it known that I, William D. Hooker, of the city of Oakland, in the county of Alameda aud State of California, have invented 5 certain new and useful Improvements in Balanced Valves for Steam-Engines; and I do hereby declare thatthefollowing is afull,clear, and exact description thereof, reference being had to the accompanying drawings.

io My invention relates to an improved method and arrangement for balancing the steampressure on slide-valves that are moved by or with or in a fixed relation to a supplemental piston; and itconsistsin tranferringthe press15 ure from the slide-valve to the supplemental piston, and then counteracting the pressure on the piston by exposing a corresponding area of the pistou to the steam-pressure in a counter direction, all as hereinafter described.

Referring to the accompanying drawings, Figure 1 is a vertical longitudinal section. Fig. 2 is a transverse section through the center of the valve-chamber and the supplemental pistou.

Let A A represent a supplemental piston 25 which is moved by steam or other pressure in the main - valve chamber of an engine, and with which the main valve B, which admits steam to and exhausts it from the engine-cylinder, is connected so as to be moved by or 30 with it. Usually this supplemental piston consists of two heads and a connecting-stem of smaller diameter, as represented in the drawings, and the main valve B is carried in a recess in its under side. As herein represented, 35 the heads of this supplemental piston are made hollow, and they are connected by two bars, c c. (Shown at Fig. 2.) In constructing these bars I cast or otherwise form a ledge, rib, or lug, d, on the inside of each, so that the two lugs will 40 be opposite each other. I then take au inverted-cup-shaped cylinder, E, on the opposite sides of which a corresponding lug or rib, e, is formed, and drop it down between the bars c 0 un til its lugs or ribs e rest upon th e 1 ugs or ribs d. 45 This arrangement I have adopted because, it is simple and answers every purpose; but the cylinder can be secured to or mounted upon the piston in the position represented in any other way. The slide-valve B fits in the recess be50 tween the heads A A of the supplemental pis* ton and below the inverted-cup shaped cylinder E.

To the upper side of the slide-valve I attach a piston, G, which will extend up into the cylinder E when the main valve is in position be- 55 tween the heads A A. This piston can be cast as a part of the valve, if desired. In the draw_rings it is represented in the form of a cup; but it can be made like any other piston, its object being to fit in the cylinder E and make a com- 60 paratively tight joint which will prevent the steam from passing into the cylinder above it. A port or passage^, leads from the space above the piston G down through the piston and main valve, so as to connect the space above 65 the piston in the cylinder with the exhaustpassage; or it might be connected with the open air with equal advantage, its object being to prevent any steam-pressure in the space. Now, when steam is admitted into the valve- 70 chamber it will press upon the top of the inverted cylinder E and upon the exposed portion of the valve that projects around the piston; but it will not enter the space in thecylinderabovethepiston. Consequently there will 75 be uo pressure in the space, and the valve will be relieved in proportion to the areas of the piston and valve, respectively. Should any portion of steam gain entrance to the space above the piston, it im mediately passes through' 80 the port i to the exhaust or to the open air, so that it is impossible to obtain any pressure upon the piston.

In constructing the valve B, piston G, and cylinder E, I regulate their respective areas 85 according to the amount of pressure I desire to takeoff the main valve. By this arrangement the valve is free to lift when the pressure underneath it exceeds the pressure above it, because the piston G can move upward in the 90 cylinder. Should the valve-rod, therefore, or any of its connections with the engine become detached or broken, the momentum of the engine will continue to move the piston until the resistance and friction stops it, iu which case 95 the pressure in the cylinder will lift the slidevalve from its seat, and thus fill the cylinder with steam, thus preventing any damage. As stated, this relieves the pressure on the valve; but it is evident that the pressure thus taken 100

253,166 off the valve is only transferred to the supplemental piston, because the cylinder E rests upon the supplemental piston, and the pressure comes on top of the cylinder and presses the 5 supplemental piston downward. This pressure on the supplemental piston can be relieved in various ways; but the simplest method is to make a port or opening, g, in the valve-chamber above each hollow head A A of the snpio plemental piston, so as to connect the interior of the chamber with the open air at such a point that each opening will be covered by the moving piston during its entire stroke, and thus prevent the escape of the steam. The 15 combined area of these openings being equal to the area of the cylinder E, the upward pressureof the steam in the hollow piston will counteract the downward pressure upon the cylinder E, thus balancing the valve and piston 20 both horizontally and vertically throughout the entire length of their stroke.

To insure an easy motion of the supplemental piston, and at the same time preserve a tight joint between the steam-space and the 25 opening g, I place a packing-ring, s, around each piston-head, on each side ofthe opening.

When tbe ends of the supplemental piston are solid, and the piston is moved by steam, either through the medium of an auxiliary 30 valve or otherwise, I provide a recess under each end of the supplemental piston, the combined areas of which are equal to the area of the cylinder E, so that the live steam will fill the recesses and exert an upward pressure cor35 responding to the downward pressure on the piston. A very suitable arrangement for this purpose is shown in my Letters Patent No. 81,168, which was issued to me on the 18th day of August, 1868, in which a puppet-valve is arranged in each end of the supplemental pis- 40 ton, so as to retain steam for cushioning the stroke of the piston. This arrangement is especially adapted for relieving this downward pressure when the admission of steam to move the supplemental piston is controlled by an 45 auxiliary valve. I do not, however, confine myself to any special arrangement for counteracting this downward pressure.