US655080A - Relief mechanism for piston-valves. - Google Patents

Description

No. 655,080. Patented July 31,1900.

a. n. HENDERSON. RELIEF MECHANISM FOR PISTON VALVES.

(Application flledvJan. 11, 1899.) (No Model.) 2 Sheets-Sheet l No. 655,080. Patented July .31, I900.

Gm. HENDERSON.

RELIEF MECHANISM FOR PISTON VALVES.

(Application filed Jan. 11, 1899.)

(No Model.) 2 Sheets-Sheet 2.

N-ITED STATES PATENT Orr-Ion.

cnonenn. HENDEnson, oFRo'ANoKE, VIRGINIA.

RELIEF MECHANISM FOR PISTON-VALVES.

SPECIFICATION forming part of Letters Patent No. 655,080, dated July 31, 1900.

. Application filed January 11, 1899. Serial No. 701,839. (No model.)

To aZZ whom it 1 7tcty c07c ce7nr V Be it known that I, GEORGE E. HENDERSON, a citizen of the United States, and a resident of Roanoke, Virginia, have invented certain.

Improvements in Relief Mechanism for Piston-Valves, of which the following is a specification. r

The object of my invention is to provide means for automatically relieving the piston- Valve of a locomotive or other engine of ex cessive back pressure, due to compression of water or steam in the cylinder of the engine of the locomotive.

Piston-valves, owing to the nature of their construction, are not able to relieve themselves the same as a' slide or D valve. The slide-valve will be raised from its seat by the excessive back pressure in the cylinder, thus relieving the pressure. Safety-valves have been provided on the cylinder-heads'for the purpose of relieving back pressure in the 10- comotive using a piston valve, but these safety-valves have proved unsatisfactory.

In the accompanying drawings, Figure 1 is a sectional view through one cylinder and valve on the line 1 1, Fig. 3. Fig. 2 is a section on the line 2 2, Fig. 3. Fig. 3 is a sectional plan view on the line 3 3, Fig. 1; and Fig. 4 is an enlarged sectional view of a portion of Fig. 2, illustrating more clearly my invention.

In the drawings I have shown simply one cylinder-casting of a locomotive of the ordinary piston-valve type. The cylinder-casting on the opposite side will be a duplicate of the one shown.

A is the cylinder-casting, having the cylinder 13, the valve-chamber O, and the steaminlet passage a and passages Z) b, one communicating with one end of the cylinder and the other with the opposite end. cis the exhaustpassage communicating with the ports at each end of the valve-casing.

Ihave omitted the piston and its rod as well as the valve, as these parts form no part of my present invention and are of the construction ordinarily used in this type of engine.

Steam is admitted from .the boiler through the central live-steam passage at to a passage 1) and into one end of the cylinder, while the steam is exhausting from the opposite end of the cylinder through the other passage 12 to the exhaustpassage 0, and when the valve is moved into the opposite position the passage of the steam and exhaust are reversed.

In the cylinder-casting A are two partitions A, forming a cavity a directly under each passage Z), communicating with the cylinder. Screwed into the partition is a valve-seat d, and adapted to the seat is a check-valve D. When the valve is opened, the passage 1) communicates with the passage ct through the cavity a; butthe check-valve is on the under side of the partition, and consequently will close with pressure in the live-steam passage a, so that the valve is normally closed when the throttle-valve of the engine is opened; but when the locomotive is standing and the live-steam passage a is free of steam under passages 19 should be increased either by undue compression or by water in the cylinder above the steam-pressure in the passage a, the valve D will be forced from its seat and the pressure in the passage 1) will be instantly relieved, thus preventing breaking or damaging the cylinder-head or piston.

While the above is the main feature of my invention and the point which the invention is intended primarily to cover, yet it affords the advantage of allowing the locomotive to drift without creating a vacuum in the steamchest. When steam is cut oif, both checkvalves D D will remain open and the air can be forced from one end of the cylinder to the other through the valves. Further, this construction will prevent locomotives from starting owing to the leaky throttle, as the steam as it slowly escapes will pass around the valves D D and into the passage Z) to the exhaust-passage 0.

Referring to Fig. 4, directly under the valve is a screw-cap-d. On removing thisscrew cap the valve and the valve-seat can be removed.

While I prefer to place the valves in the particular position shown, they can be placed at any point in the partition between the live;

steam passage or and the cylinder-passages b b, as in some types of engines it may not be convenient to place the valves in the position shown in the drawings. If the valve is placed without departing from' the main feature of my invention.

y ;I claim-as myinvent-ion- 1. The combination of a cylinder, a cylindricalvalve-casing, a central steam-inlet pas sage,sidecylinder-passages and end exhaustpassages,cavities extending from the livesteam passage under the cylindenpassages, ports in the partition between the cavities and the cylinder-passages, a check-valve in each-port normally open but closing against steam-pressure in the live-steam passage and opening against said steam-pressure when there is excessive back pressure in one or other of the cylinder-passages, substantially as described.

2. The combination in a locomotive, of a steam-cylinder; a cylindrical valve-chest,

live-steam and exhaust passages'lea'ding to said 'valve-c'h'es't and ports leading to the steam-cylinder, a chamber to one side and'below said valve-chest communicating with the live-steam passages, two check-yalves in the ;partition.between the saidchamber and the steam-ports of the cylinder, said valves being normall-yheld-open by gravity, substantially as described.

The combination'in a locomotive-cylim .dercasting, of a steam-cylinder, a cylindrical val ve-chest, passagesleadin g fro m said valve- "chest "to-the steam' cylinder, to the exhaust and to the live-steam supply, a partition forming with the walls of the cylinder a-chamber communicating with the live-steam passages, and check-valves with valve-seats in said partition opening into the passages tothe-steamcylinder, threaded openings in the lower wall of said ohamberdirectly beneath the'checkvalves through which both valves and seats may be introduced and fitted in place and threaded plugs constructed toclose said openings, said valves and threaded openings being inside of the locomotive-frame and so placed as to be readily accessible, substantially as described.

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

GEORGE R. HENDERSON.

' Witnesses:

R. H. PERsrNeER, JNo. A. PILOHER.

Images