US11607A - Slide-valve fob - Google Patents

Description

UNITED STATES PATENT OFFIOE.

JOHN GLEASON, OF NORTHFIELD, VERMONT.

SLIDE-VALVE FOR STEAM-ENGINES.

Specication of Letters Patent No. 11,607, dated August 29, 1854.

To all whom t may concern Be it known that I, J oI-IN GLEAsoN, of Northfield, in the county of Washington and State of Vermont, have invented certain new and useful Improvements in Slide-Valves and Steam-Chests of Locomotives and other Steam-Engines; 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- Figures 1 and 2 are both longitudinal sections of a steam chest and slide Valve of a' valve, and the opening of t-he steam ports,-

to the full width, very early in the stroke of the engine.

My invention consists, secondly in the employment in the covering plate before mentioned of certain safety valves, whereby on the breaking or giving way of the valve gear all danger of bursting the cylinder by the compression of the steam in front of the piston is efectually obviated by allowing the steam to return through the steam` way and valve into the steam chest.

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

The valve seat, A, only diiers from the seat of the common slide valve, in having the steam ports (a, widened to the extent shown in both figures of t-he drawing, where the ordinary width, which is the same as the width of the steam ways, D, D, is indicated by blue lines. This enlargement it will be seen is all on the outside, and is gradual commencing a short distance down the passage, and it makes the width of the ports about one-third greater than that of the steam ways.

The construction ofthe valve, B, will be best understood by reference to Fig. 1. It is made of uniform thickness, from end to end, and is faced parallel on its upper and Its length is such that when` in the center of the valve through which the steamhis exhausted is of such length as to be capable of extending exactly from the inner edge of one steam port, to the inner edge of the other, and from this cavity (b) there is an opening (7c) through the back` of the valve, which is of the same length as, but wider than, the exhaust port (c). Midway between the cavity (b) and the ends of the valve, there are two passages (d, d) of the same length as the steam port-s, and of the same width as the steam ways, D, D', at the part where there is no enlargement. The parts (f, f) of the faces of the valve, between the ends of the valve, and the outer sides of the passages, and the parts (e, e) between the said passages* and the exhaust cavity (b) are all exactly equal in width, to the excess of the width of the steam ports above that of their passages, so that when either of the said parts of the face cover the ports, the port is still open to the full effective width, equal to the width of the steam way. The passages, through the valve do not extend directly upward square with the face but are curved toward the center.

The covering plate, C, is intended to be made of cast iron and bolted to the cover of the steam chest. It is faced on its under side to fit closely to the back of the valve, and in its face, there are two cavities, (g, g) the outer sides (it, 7L) of which are directly opposite the outer edges of the steam ports, and the inner edges, (i, i) of which are at a distance apart equal to the width of the opening (7c) in the back of the valve.

The operation of the slide valve is best illustrated in Fig. 2, where it is supposed to be moving in the direction of the black arrow, and is represented in black outlines and tinted, in the position it occupies, while- 1passes over the valve, through the cavity (g) in the covering plate, and the passage (d) in the direction of the red arrows (2, 3, 4,) and enters the port (a) by that course. The valve reaches the position shown in red outline when the piston has made about onefifth of its stroke, and it will be understood, that as the space between the end of the valve, and the outer edge of the port, is then equal to half the widthv of the steam -way, and the space between the top edge of Vthe valve, and the edge of the cavity (g) is of the same width, that the full width of 'opening is obtained-The partsk (f) and (e) of the face of the valve being of no greater width, than the excess of width of the port, always give the full amount of opening at the port, provided there Ais opening enough at the top andv bottom edges of the end of the valve. The full width of opening continues during the retreat-ing motion of the valve until the piston has arrived very near where the steam is shut off. The exhaust.

steam escapes from the steam way,'D, directly into the cavity in the direction of the arrow (5), and also through the passage (cl) the cavity (g) and theopening (la) in the direction of the arrows 6 `8f 7 The gain in time byk this invention in opening the steam and exhaust ports, will be exactly onehalf, and `in addition to this,` the admission of steam to the back of they valve to balance it, is 'accomplished without other provision being made for that purpose.

The safety valves, E, E, for preventing the bursting of the cylinder, are placed inr the cavities (g, g) of the covering plate, C, and steam space is left in the steam chest above the said plate. The valves may be of any kno-wn form capable of being lifted by the ressure of steam below them. The

cavities (g, g,) are always in communication through the passages (d, 0V) with their respective steam ways, D, D', and during the induction of the steam through the ports, are balanced by the steam above and below, but if the valve gear should give out, and the valve suddenly become stationary, leaving no opening for the escape of the steam which must'have been left at the time of its stoppage, in one end of the cylinder and' one steam way, Vthe compression of this steam by the continued motion of the piston, will cause'the safety valve, E, in the cavity y(g) which is in communication with that steam way, tc be lifted, andk the steam will have free escape into the steam chest.`

This invention can be `applied to any steam engine, previously rusing the common slide valve, all that is necessary being to enlarge the steam ports (ci, d) to the extentrepresented, and construct a new valve,

rB, and apply. a covering plate, C, as de` scribed. If there should not be sufficient height in the old steam chest, to receive the valve and covering'plate, a new one may b e `made at little expense compared with the advantages to be derived. The same eccentric, valve gear &c are all applicable to the new valve.

What I claim as my invention and desire to secure by Letters Patent` is,

1. The valve B, constructed as described .in combination with the cavities (g, g) in

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