US380918A - Steam-engine indicator attachment - Google Patents

Description

(No Model.)

J. R. MITCHELL. STEAM ENGINE INDICATOR ATTACHMENT.

Patented Apr. 10. 1888.

UNITED STATES PATENT OFFICE.

JOSEPH RAMSDEN MITCHELL, OF OAKLAND, CALIFORNIA.

STEAM -ENGINE. INDICATOR ATTACHMENT.

, I SPECIFICATICN forming part of Letters Patent No. 380,918, dated April 1888.

Application filed November 8, 1886. Serial No.2l8,333. (No model.)

To a ZZ whom, it may concern.-

' Be it known that I, JOSEPH RAlVISDEN MITCHELL, of the city of Oakland, county of Alameda, and State of California, have invented an Improvement inIndicator Attach ments; and Ihereby declare the following to be a full, clear, and exact description thereof.

My invention relates to the class of indi cators for engines; and my invention consists, broadly, in a novel connection with the cardbearing cylinder of the indicator, whereby the limits of oscillation of said cylinder are shifted to provide for consecutive separate diagrams on the indicator-card, and, further, in such a connection as will effect said shifting at the time when the pencil describing the diagram is moving upon the exhaust -line, or line parallel to the atmospheric line, whereby any distortion of the diagram is prevented.

My invention consists, particularly, in a cord for effecting the usual partial rotation of the cylinder, and which is so connected as to alter its len th, whereby the cylinder is given or allowed to have an additional movement to vary the position of the diagrams on the card, and, finally, in the novel connection of the cord, whereby its length is automatically altered, all of which I shall hereinafter fully describe.

My invention has for its object the making of distinct and separate consecutive diagrams on the same card. I

Referring to the accompanying drawings, Figure 1 is an elevation showing the attachment in connection with the cylinder of the indicator, the card 1 of which, and also the card 2 below, for the sake of showing the diagrams,

- being shown extended instead of wound around the cylinder in normal position. Fig. 2 is an elevation showing the change in the position of parts for changing the time of shortening the connecting-cord from the beginning of, say, the forward stroke to the beginning of the return-stroke.

The indicator proper, which may be of any of the ordinary types, is sufficiently illustrated herein by its cylinder P, to which is attached the card 1, which, though normally encircling the cylinder, is here shown extended, for the purpose of exhibiting the independent consecutive diagrams 1 2 3 4 5, which are the result of my attachment. 4

It will of course be understood that the cylinder P, as usual, is influenced by a spring (not shown.) tending to turn it back.

A is a frame or standard, to be secured to the engine, and to which the lever B is pivoted by pin or stud 0, upon which it vibrates, said lever being supposed to be connected with the cross-head of the piston-rod, as usual, whereby it is operated.

L is a cord, one end of which is wound on the end of cylinder P. In ordinary cases the other end of the cord is attached directly to the lever B, whereby, as said lever moves over in the direction shown by arrow 1, the cord L turns the cylinder, the pencil meanwhile describing the diagram on the indicator-card, and as the said lever returns the cylinder turns back under the influence of its spring, and keeps the cord taut. In this operation it will be seen that as the limits of oscillation of the cylinder are unvarying, the diagrams are more or less coincident, and an attempt to describe several simply results in confusion of lines.

- I propose by my invention to shift each time the limits of the cylinders oscillation, so as to avoid coincident diagrams, and in their stead to make a series of independent consecutive diagrams, as shown by 1, 2, 3, 4, and 5. Instead, therefore, of maintaining a given length of cord, L, as is usually done, I provide for such a connection of said cord that at each effort it shall have its length varied, (here shown, for example, as shortened,) and while I do not wish to confine myself, as far as the principle of my invention is concerned, to the connection here shown and described, such connection is sufficient for this application.

In the lever B is mounted a drum, H, to which the cord L is attached, and from which it passes down and is guided properly to the cylinder P. Upon the drum is a ratchet, G, which is engaged by a retaining-pawl, K, and by an actuating'pawl, F; This latter pawl is pivoted in thelower end of an elbow or bellcrank lever, B, .fulcrumed at D and having in its upper end a stop-screw, M, which in some cases, as .in Fig. 2, is set down to impinge on the head N, formed on the upper end of lever B.

The operation is as follows: In Fig. 1 when the leverB is moved in the direction of arrow 1 the immediate effect is through the engagement of the ratchet G with the actuating-pawl F to turn said ratchet slightly-say one toothso that the drum II is partially rotated, which, winding up, shortens the cord L, thus providing for a more extended movement of the indicator-cylinder P at the start than it would have from the movement of lever B alone. The retaining-pawl K holds the drum and cord against the return of the cylinder acting under its spring. The same thing occurs on the forward movement again, the cord Lbeing shortened up once more, so that the limits of the cylinders oscillation are constantly varied, which enables it to present the card it carries in various positions to the pencil and providing for the series of consecutive diagrams 1, 2, 3, 4, and 5, card 1. Now, as the change of length of cord L must take place on the forward strokes when the engine is running ahead and on the back-strokes when running back, I effect this change by the stop'screw M, which, as shown in Fig. 2, is set down to contact with the head N of lever B. In this figure the lever B is supposed to be starting in the direction of arrow 2, and as at starting the contact of the head N and stop-screw M holds the lever E to move with the lever B, the e11- gagement of the ratchet G with the pawl F of said lever turns said ratchet and effects the shortening of the cord L, with the result as before described, the only difference being in the change of the time when the cord is shortened and in the direction of the diagrams l, 2, 3, 4, and 5, as shown in card 2. In either case it will be seen that as the shortening takes place right at the start of the stroke there will be no distortion in the diagrams, as the change takes placewhen the pencil describing the dia; grams is moving upon the exhaust-line shown in cards 1 and 2 by the figure 8. Though I have described the shifting of the cylinders limits of oscillation as taking place through the shortening of cord L, it is apparent that by periodically lengthening the cord the same result may be had, as the cylinders spring will turn it back to a new position.

By my invention I can obtain a series of consecutive diagrams separate and distinct, and giving with unfailing accuracy the performance of the governor, showing at a glance whether there is any irregular movement, and also presenting at one view many other points desirable to be known, and which can only be ascertained by a series of consecutive diagrams. By the use of two indicators-one at each end of the cylinder-a series of diagrams following consecutively from each end of the cylinder can beobtained, showing thirty or forty revolutions of the engine, all on two cards, which can be taken at one view. I can by this attachment take a number of diagrams on one card at intervals of several revolutions by turning the drum H and ratchet Gr by hand. I take a diagram, then turn the ratchet-wheel a space of two or three or any desirable number of teeth, then take another diagram, and continue until the end of the card is reached. 1 thus have presented on one card the performance of the engine under different loads or arrangement of the valves. I save time, also, by the use of my attachment.

By the old method only two or three diagrams of varying pressures can be taken without becoming hopelessly mixed and blurred, and no consecutive action of the governor during a number of revolutions can be obtained.

I obviate these difficulties and can obtain a correct record of the governors action through a number of revolutions, thereby giving a much more ready and accurate means of ascertaining the-performance and conditions under which the machine is working.

The device for changing the length of the cord can be stopped or started at pleasure with the machine running at full speed.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, is-

1. An indicator for determining the performance of an engine or other similar machine, said indicator having a card on which the diagram is traced, in combination with the vibrating lever receiving its motion from said engine or other machine, and a conncctlon for I varying thelength of connection between said lever and the indicator, whereby a series of consecutive separate diagrams are made on the card,-substantially as described.

2. In combination with an indicator-cylinder for carrying a card on which a diagram is traced to show the performance of an englne or other machine, a vibrating lever,and a connection between said lever and the indicatorcylinder, whereby the cylinders limits of oscillation are shifted to provide for making a series of consecutive separate diagrams on the indicator-card, substantially as described.

3. The vibrating lever deriving motion from the engine or other machine, and the card-bearing cylinder of the indicator, in combination with a cord and the vibrating lever attached thereto, so as to vary the length of connection when the lever moves, whereby the cylinders limits of oscillation are shifted to provide for a series of consecutive separate diagrams on the indicator-card, substantially as described.

4. The combination, with an indicator-cylinder for carrying a card on which a diagram is to be traced to show the performance of an engine or other machine, and a vibrating lever deriving motion from said engine or machine, of a cord connecting the lever with the indicator-cylinder, whereby the limits of oscillation of said cylinder are shifted to provide for making a series of consecutive separate diagrams on the indicator-card, substantially as described.

5. The combination,with the vibrating lever deriving motion from the engine or other machine,and the card-bearing cylinder of theindicator, of a cord attached at one end to the cylinder and a connection between its other end and the vibrating lever,whereby its length is varied at the beginning of the movement of ratchet as thelever moves and turning it partially, substantially as described.

7. The combinatiomwith the cord, the indicator-cylinder, the vibrating lever, and the w means for shortening said cord,f0r the purpose described, and holding it, of a drum carried by the lever and to which one end of the cord is attached, a ratchet on the drum, a pawl engaging the ratchet as the lever moves and turning it partially, and a retaining-pawl for holding it to the position turned,substantially as described.

8. The combination,with the cord, the indicator-cylinder, the vibrating lever, and the means for shortening said cord at the begin- 'ning of either stroke'of thelever, and for the purpose described, of a drum carried by the 3c lever and to which one end of the cord is attached; a ratchet onthe drum, a retainingpawl engaging the ratchet, an actuating-pawl for turning it, a pivoted lever carrying said pawl, and a connection between said pawl- 5 lever and the main vibrating lever, whereby the engagement of its pawl with the ratchet is varied as to time, substantially as described.

In witness whereof I have hereunto set my hand.

JOSEPH RAMSDEN MITCHELL.

Witnesses:

S. E. MITCHELL, S. A. TRAGO.

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