US27341A - Pbesstjre-gage for steaffi-boilers - Google Patents

Description

E. H. ASHCROFT.-

Pressure Gage.

Patented March 6, 1860.

No; 27,341. v

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EDYVARD H. ASHCROFT, OF BOSTON, MASSACHUSETTS.

PRESSURE-GAGE FOR STEAM-BOILERS.

Specification of Letters Patent No. 27,341, dated March 6, 1860.

To all whom it may concern:

Be it known that I, EDWARD H. ASH- oaor'r, of Boston, in the county of Suffolk and State of Massachusetts, have invented an Improved Pressure-Gage for Steam- Boilers; and I do hereby declare the same to be fully described and represented in the following specification and the accompanying drawings, of which Figure 1, denotes a front view: Fig. 2, a longitudinal section, and Fig. 3, a transverse section of a pressure gage provided with my invention.

For moving the indicator or index pointer of a steam pressure gage it has been customary to apply to its arbor, a small gear or pinion to engage with a rack extended upward from the diaphragm (or the spring thereof,) of the gage. Besides this, a retractive spiral spring has also been applied to the arbor of the indicator for the purpose of bringing back the indicator as the pressure of the steam may slacken. It will readily be seen that when the pressure of the steam is great, or fifty or one hundred pounds to the square inch, the spi *al spring will be very much contracted, and as a matter of course will cause the bearing teeth of the pinion and rack to bear quite hard against one another. Now under these circumstances, when a steam pressure gage is in use on a locomotive steam engine in movement 011 a railway, the undulations of the track will produce such a jolting or jarring of the engine, as to keep the tooth surfaces in contact in continual movement on one another, more or less. This movement, under the great pressure of the spring exerted to force one tooth against the other, soon materially wears the teeth, and seriously affects the efficiency and accuracy of the gage.

The object of my invention has been to overcome the above mentioned difliculty. In doing so, I discard the rack and pinion entirely, and in the place of the pinion, I affix on the arbor, a, of the index pointer, b, of the gage (see Figs. 1, 2-, 3,) a wheel or barrel, 0. To this wheel I affix one end of a chain (Z, and wind such chain around the periphery of the wheel and fasten the outer extremity of the chain to the upper end of the superior arm of a bent lever, 6, arranged within the gage case A, and so as to turn on a fulcrum f, as shown in Fig. 2. The inferior arm of the said lever is jointed to a rod or bar, g, so connected with the elastic diaphragm, h, as to be moved thereby and therewith. As the pressure of the steam increases, the superior arm of the bent lever will be moved out-ward, and so as not only to draw on the chain and rotate the wheel or barrel, 0, and the arbor of the indicator, but to wind up the spiral retractive spring, 2', of the indicator arbor. In this way, the index hand will be moved over its divided plate or limb, k, and owing to the application and arrangement of the working parts, the jar and movements of the 10- comotive engine, when the pressure gage is used thereon, and such engine is in use, will create none of the rubbing and wear of the surfaces and perturbations of the indicator, such take place when the rack and pinion are employed as described. My improvement though simple is one of great value in the pressure gage.

I do not claim the usual arrangement and application of a rack and pinion to the index pointer, and the diaphragm of a steam pressure gage, nor do I claim any application of gearing to the index pointer in order to operate it, for it has been an object with me to avoid the use of any gears or racks of any kind, or any devices, which by the constant jarring of the locomotive engine while it may be in movement on a railway, could wear or become injured.

I am aware, that in a pressure gage, a shaft connected with an index pointer shaft by two gears, has not only been operated or turned in one direction by a flexible strip or belt coiled around it and attached to a lever resting on the diaphragm spindle, but has also been moved or turned in the opposite direction by a heavy pendulum or weight applied to an arm projecting from the shaft. Such devices or mechanism for operating the index pointer shaft, would be subject to such movements, if employed on a locomotive engine boiler, as to destroy or materially injure their efiiciency. The constant vibrations which would be produced, in the weight would generate in it such momentum and percussive force as not only to very soon destroy the teeth of the gearing, but subject the index pointer to such continual and extensive vibrations on its are as to render it difficult to ascertain by it the proper pressure of the steam. In my improved gage, I apply a coiled spring directly to and so as to coil around the indicator shaft, and to cooperate with a chain cl, and lever, 6, arranged and applied to it and the diaphragm rod d, as hereinbefore described and as shown in the drawings. Now, although the spring serves to rotate the index pointer shaft in one direction, its rotation in the opposite direction being produced by the lever and chain the coils of the spring are so arranged that the action of the locomotive engine or the jars and shocks of it While running on a railway can produce no improper swayings or deflections of the index pointer, such as Would take place Were a Weighted arm or pendulum applied to the indicator shaft. Thus, it Will be seen that in my invention of my improved gage, the spring and the chain and lever do something more than merely effecting the rotations of the indicator shaft, for the arrangement of the lever is such that the portion of the chain extending from it to the index pointer shaft is horizontal or about so, and consequently thus prevents the vertical shocks of the engine from affecting the index pointer.

My improved gage is perfect in its operation, the index pointer maintaining great steadiness under equality of pressure Whatever may be the speed of the engine or the amount of shocks or jarring of it produced by inequalities or irregularities of the rail- Way track.

lVllat therefore I claim is My improved locomotive engine boiler steam gage as made With the coiled spring the chain and lever arranged and applied directly to the diaphragm rod and the index pointer shaft in manner and so as to operate substantially as described.

E. H. ASHCROFT. Witnesses R. H. EDDY,

F. P. HALE, Jr.

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