US425265A - smith - Google Patents

Description

2 Sheets-:Sheet 1.

(N0 Mudel.) W. MSMITH.

RELIEF VALVE FOR LOCOMOTIVES.

No. 425,265. Patented Apr. 8, 1890.

I" .1. F W h n (No Model.) 2 Sheets-Sheet 2.

W. M. SMITH.

RELIEF VALVE FOR LOCOMOTIVES.

Patented Apr. 8, 1890.

UNITED STATES PATENT Fries,

lVALTER MACKERSIE SMITH, OF JESMOND, NEVVCASTLE-UPON-TYNE, COUNTY OF NORTHUMBERLAND, ENGLAND.

RELIEF-VALVE FOR LOCOMOTIVES.

SPECIFICATION forming part of Letters Patent No. 425,265, dated April 8, 1890.

Original application filed July 3, 1889, Serial No. 316,477. Divided and this application filed September 3, 1889. Serial No. 322,817. (No model.) Patented in England January 11, 1889, No. 571; in France June 5, 1889, No. 198,750, and in Belgium June 5,

To all whom it may concern.-

Be it knownth at I, WALTER MAOKERsIE SMITH, a subject of the Queen of Great Britain and Ireland, residing at Jesmond, Newcastle-upon-Tyne, in the county of Northumberland, England, have invented certam new and useful Improvements in Relief-Valves for Locomotive-Engines, (for which patents have been obtained in England, No. 571, dated IO January 11, 1889 in France, No.198,750, dated June 5, 1889, and in Belgium, No. 86,529, dated June 5, 1889,) of which the following is a specification. D

This application is filed as a division of my I 5 pending application for United States patent,

filed July 3, 1889, Serial No. 316,477.

This invention has for its object improvements in locomotive-engines.

Balanced valves have been used for distributing steam in most classes of engines. In marine and other engines they always work under pressure of steam, whereas locomotiveengines when descending inclines have their momentum kept up by the action of gravity and continue to move after steam has been shut off. Assuming balanced valves, including piston-valves, to be employed instead of the ordinary slide valves, the actlon of these valves may be compared to what would occur assuming an ordinary slide-valve to be used that could not rise or lift off the face; hence by the action of the engine piston steam would be exhausted from the steampipe and steam-chest, and, the valve not be- 3 5 ing able to lift, no air could pass from the atmosphere into the steam-chest, except the small quantity that would pass in at the end of each stroke, and which would be qulckly drawn out again by the recedlng piston. In consequence the engine would be unnecessarily retarded. Air passing down the exhaustpipe would press on the piston 1n the opposite direction to that in which it mlght be moving, and this pressure not being nearly counterbalanced by that due to the rarefied air pressing on the opposlte side of the piston,

' there would result undue tension of the piston-rod and connections durlng the backward stroke and undue compression during the forward stroke. Now, according to this invention, the foregoing disadvantages are obviated by admitting steam alone in an automatic manner to the steam chest or cylinder of a locomotive which is running with the steam shut 0%. To this end the steam is admitted 5 5 automatically to the steam-chest and thence to the cylinder by a suitable valve or valves opened or caused to open by the pressure of the atmosphere when the pressure within the steam chest or cylinder falls below that of the atmosphere. The steam so admitted acts as would steam admitted in the usual Way from the boiler, and thus serves to prevent rarefaction in the steam chest and cylinder, so that at least a pressure equivalent, or approximately so, to that of the atmosphere is exerted on both sides of the piston until the distributing-valve cuts off communication with that part of the cyl inder behind the receding piston, when the inclosed steam will expand, decreasing in pressure. Toward the end of the stroke thespace in the cylinder on the opposite side of the piston by the same means has its communication out off from the exhaust, the 7 5 steam being then compressed and forming a cushion which arrests the movement of the piston, thereby obviating undue strain such as hereinabove referred to. A similar result might be obtained by admitting steam direct to the cylinder without passing through the steam-chest, when the pressure of the fluid exerted on the back of the receding piston would vary little throughout the stroke. The steam is caused to be admitted in limited quantities when the main supply of steam is shut off at the regulator. To this end a piston is employed, or its equivalent, subject on one side to the atmospheric pressure and on the other side to the pressure in the steam 0 chest or cylinder. This piston is arrangedto operate a valve-it may be a clack-valve or a piston-valve-whieh controls the connection between the steam chest or cylinder and the boiler. lVhen the atmospheric pressure is 5 greater than the pressure in the steam chest partly in elevation, so much of a locomotive-- engine as is necessary to illustrate the application thereto of apparatus according to this invention for automatically admitting steam alone to the steam-chests of the cylinders.

Fig. 2 shows in longitudinal vertical section, to an enlarged scale, one of the apparatus detached, the steam-valve and part of the airactuated piston being shown in elevation.

Fig. 3 is an end elevation of the apparatus.

Fig. 4 is a transverse section on the line 0 P. 1

Referring to Fig. 1, 1 is one of the workingcylinders of the engine, and 2 the steam-chest of such cylinder.

3 3 are liners in the steam-chest.

the example shown.

4 4 are live-steam spaces. 5 is an exhaust-steam space. 6 6 are steam-ports in the liner. 7 7 are cylinder-ports. 8 8 are exhaust-ports in the liner.

To each steam-chest 2 is fitted, as shown in Fig. 1, an apparatus of the kind shown in Figs. 2, 3, and 4. This apparatus comprises a piston 21, arranged to slide in a casing 22," the interior of which communicates by a branch pipe 23 with the steam-space 4 in the steam-chest 2. The piston 21 is subjected on its outer side (11. e., the surface that faces to the left in Fig. 2) to the pressure of the atmosphere and on its inner side (t'. a, the surface that faces to the right in Fig. 2) is subjected to the same pressure that exists for the time being in the space 4 of the steam-chest. The piston 21 is formed with a shoulder at 24, that serves to limit its outward movement. It is also formed or provided with a spindle or stem 25, that slides in a tubular guide 26,

a pressure in the steam-chest the piston 21 will move inward and its stem 25, acting against the stem 31 of the steam-valve 29, will force v is in 1 these liners that the piston-valves 3 work in mospheric pressure, the piston 21 will move in the opposite direction, releasing the steamvalve 29, which will then be forced uponits seat and will cut off the supply of steam.

From the foregoing description it will be understood that although the main. supply of steam may be cut off at the regulator the steam-pressure in the space 4 of the steamchestcan never be reduced below that of the external atmosphere for the time being. At each stroke of the working-piston of the engine steam will be drawn past the valve 29, the steam-space 4, and one of the ports 7 until the cut-off takes place. This steam will then be expanded through the remainder of the stroke until the eXhaust-port'op'ens, whereupon there will be a slight inrush of air from the exhaust-pipe 5 On the return-stroke of the working-piston of the engine the steam from the engine-cylinder 1 will be expelled through the port 7, the exhaust-space 5, and

the exhaust-pipe 5 until the port '7 is again closed, whereupon the remaining steam will be compressed, and this compressed steam will act as a cushion to the working-piston of the engine until the port 7 is again opened 1 to the steam-space 4. The steam so admitted will act as a lubricant to the internal working parts.

The apparatus hereinbefore described tomatically comes into operation after the main supply of steam has been cut ofi at the regulator and continues in operation until the engine comes to rest, effectually preventing the pressure in the steam chestor cylinder, or in each, if applied to more than one, falling appreciably below that of the external atmosphere. When the engine comes to rest, the air-actuated plunger and steam-valve will be automatically operated in the reverse di= rection by the pressure within the steam chest or cylinder, and the automatic admission of steam will thus be arrested.

This invention will enable a balance-valve to be used for the distribution of steam to the cylinders of a locomotive without unnecessary strain being put on the piston rod and other parts of the engine.

Apparatus according to this invention may be used in connection with valves other than I balanced valve'sfor instance, with valves placed on the tops of cylinders and which do not fall from the faces.

\Vhat I claim is- 1. Apparatus for automatically admitting steam alone to the steam-chest or to the cylinder of a locomotive-engine and comprising a casing 22, provided with an inlet branch for steam and adapted to be connected to a steam pipe and an outlet branch adapted to be connected to and with its interior in communica tion with said steam chest or cylinder, a valve 29, with stem 31, for controlling said steam inlet, and a piston 21, arranged to slide in said casing and provided with a stem 25, adapted to act against said valve-stem 31 and open said valve when moved in one direction, said piston being subject on one side to the pressure of steam in the casing and on the other side to the pressure of the external atmosphere, substantially as herein described.

2. The combination, with the cylinder 1 and steam-chest 2 of alocomotive-engine, of a piston distributing-valve 11, arranged to'work in said steam-chest, an apparatus for automatically admitting steam alone to'said steamchest when the pressure therein falls below that of the external atmosphere, and an external steam-pipe 28, for connecting said apparatus to the locomotive-boiler, said apparatus comprising a casing 22, secured to said steam-chest and having an outlet 23 in communication therewith and a steam-inlet in communication with said pipe 28, a valve 29, with stem 31, for controlling said steam-inlet, and a piston 21, arranged to slide in said casing and provided with a stem 25, capable 20 of acting against said stem 31 and opening said valve when moved in one direction, said 7 piston being subject on one side to the pressname to this specification in the presence of 0 two subscribing witnesses.

WALTER MAOKERSIE SMITH.

Witnesses:

ROBERT STIRLING,

14 Richmond Terrace, Gateshead-on-Tyne.

WILLIAM FORSTER,

10 Airey Terrace, Gatesheadmn-Tyne.

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