US549458A - mceinney - Google Patents

Description

(No: Model.) 3 Sheets--Sheet 1.

` W. s. MGKINNEY;

A LIFTING JAGK.

No. 549,458. Patented Nov. 5, 1895.

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(No Model.) 3 sneetsshee 2.

W. S. MGKINNEY.

LIPTING JACK.

No. 549,458. y Patented Nov. 5,1555.

. I Rf, 'h y R? Hf .Hmlmw WH @s vl (NO Model.) 3 Sheets-Sheet 3.

W. s. MGKINNBY. 1

LIPTING JACK.

No. 549,458. y Patented NOV. 5, 1895.

lIii .H WHIMHL is E. H A ...l r'I ...zu H u UNITED STATES PATENT OFFICE.

VALTER S. MCKINNEY, OF CHICAGO, ILLINOIS, ASSIGNOR TO MOSES M. MOORE, l OF SAME PLACE.

LlFTlNG-JAC K.

SPECIFICATION forming part of Letters Patent No. 549,458, dated November` 5, 1895.

Application iled February 27, 1895. Serial No. 539,913. (No model.)

T0 all whom. t may concern.-

Be it known that I, WALTER S. MCKINNEY, a citizen of the United States, residing at Chicago,y in the county of Cook and State of sented, viz: First, mechanism for liftingthe bar with its load; secondly, mechanism for dropping the bar suddenly at will with or without its load, and, thirdly, mechanism for lowering the bar gradually when required. Of these three features the first two are always essential, but the presence of the third may be made to depend upon the character of work for which the lifting-jack is designed. Thus, for example, if the lifting-jack is to be used exclusively as a track-j ack the third Vfeature may be omitted; but if intended to be used as a car-jack the three features should be present.

The nature of my improvements will be understood from the following description, reference being had to the accompanying drawings, of which- Figures l and 2 are central vertical sections of my device, showing the liftin g mechanism in different positions and showing the mechanism for gradually lowering the lifting-bar in its inactive position; Fig. 3, a view similar to Fig. l, but showing the mechanism for gradual lowering of the bar in its active position; Fig. 4, a side elevation of the upper portion of the standard, showing the handle for effecting quick release of the lifting-bar and showing the switch for throwing the mechanism for gradual lowering of the bar into and out of active position; Fig. 5, a vertical section of the device taken on the line 5 5 of Fig. 1 and viewed in the direction of the arrow, and Figs. G, 7, and 8 detail views.

A is the standard within and upon which all the operative parts are mounted; and B the liftingbar provided with a head z', foot y, and ratchetteeth oc, and sliding vertically in the standard, as usual.

As above intimated, the primary object of my invention is to secure a lifting-jack of great lifting power, and to this end I operate the pawl C indirectly from the hand-lever D through the medium of a compound lever system, partaking in a measure of the nature of toggle-levers. A description of this part of my device is as follows: The hand-lever D is fulcrumed to the standard at w. At its inner end it is provided with lateral lugs fv, one at each side, andupon each of these lugs is pivoted a link E. The links vE in turn are provided with lugs fu., projecting laterally outward from them, and upon these lugs are pivoted links VF, pivotally mounted toward their lower ends upon a'shaft t in the stand ard. The two links E are jointed together by a cross-pin s, which is not in line with the lugs u, their relation being shown by full and dotted lines in Fig. 6 and by an end view in Fig. 7.

An examination of the several iigures will show that when the link E approximates a horizontal position by downward pressure upon the long arm of the socket-lever D, the lugs u and cross-pin s are in vertical line with each other, or substantially-so, as shown in Fig. 2, and by the raising ofthe long arm of the socketdever D and consequent deflection of the links E from the horizontal, the cross-pin s is rocked away from the vertical, as indicated by the full and dotted lines in Fig. 1. The pawl C is pivoted at its lower end upon the cross-pin s, and accordingly with each stroke of the socket-lever D it is raised, not only to the extent produced by the movement of the link F from the inclined position shown in Figs. l and 3 in the vertical position shown in Fig. 2, but also to the extent produced by the movement of the cross-pin s from the inclined position with relation to the lugs u shown in Figs. 1 and 3, to the ver# tical position with reference to those lugs shown in Fig. 2. It will thus be seen that the several jointed members constituting the lever system form a compound lever operating ultimately upon the pawl C with greatlymultiplied force. To maintain the pawl normally in contact with the ratchet-teeth m on the lifting-bar, and also to permit it to be withdrawn from contact with the ratchet and secured there when it is desired to drop the bar suddenly, the following mechanism is provided: From nea-r the upper end of the pawl a piu r projects laterally through the standard, the form ot` the opening through which it projects being shown at q in Fig. 8, the opening having a depressed offset q. To the pin 7' a tlat spring p is secured which projects downward and bears against a pin r' project-in inward from the wall of the standard. By raising the socket-lever and pulling upon the projecting portion of the pin r, the pin may be brought into the offset q, which holds the pawl out of contact with the ratchet in opposition to the spring p.

lt is of course necessary with this, as with all lifting-jacks, to provide means for retaining the bar in its raised position between the downward strokes of the socket-lever, and for this purpose I provide two contiguous metal blocks G and G', sliding in guides in the upper part of the standard and provided on their ends which are toward the liftingbar with teeth ai to engage the ratchet-teeth it. I prefer to provide one of these blocks with teeth of the same height as those of t-he lifting-bar and the other block with teeth of half that height, in order that the bar may be engaged and held even when only slightly raised from any given position that it may be in. Two springs o, bearing against the standard and the blocks, maintain the latter normally in engagement with the lifting-bar. Obviously, as the bar is raised, the teeth of the ratchet thereon pass the teeth of the blocks G and G', the latter being forced back su liiciently in opposition to the spring o, and

returning instantlyv when the teeth have cleared each other. To drop the bar suddenly, therefore, it is obvious that the blocks G and G, as well as the lifting-pawl C, must be withdrawn from contact with the ratchet of the lifting-bar, and for this purpose the following mechanism is provided:

From the outer faces of the blocks G and G pins lr2 project. Extending laterally through the upper end of the standard and projecting from each side thereof is a pin n, to which are rigidly secured two arms m in position to engage the pins r2. Mounted upon the projecting ends of the pin n is a yoke-handle ll. This yoke-handle might be rigidly connected to the cross-pin ln, but I deem it preferable, in order to prevent accidental operation, to mount it loosely on the cross-pin and provide means for connecting it rigidly at will. These means are as follows: Upon one side of the standard an arm rigid with the cross-pin n, projects downward at an angle parallel with the adjacent arm ot the yoke. On the outer face of that arm of the yoke is a fiat spring p', having upon it a stud 7i, passing through a hole in the arm and capable, when pressed inward in opposition to the spring, ot' entering a recess in the iixed arm Then this construction is employed, and it is desired to lil't the yoke-shaped handle for the purpose ol.' retracting the blocks G and G/, the pin 7o is pressed inward, causing it to engage the arm l', and the handle then raised. It is not necessary to continue the pressure upon the pin 7:, since after the lifting of the yokeis begun the spring p is insuiiicient to overcome the friction of the pin 7c in its recess. \Vhether the yoke-handle is permanently rigid upon the cross-pin '1L or adapted to be temporarily locked to it by means such as those last described the operation of lifting it is to cause the arms m to bear against the pins r2 and retract the blocks. The pawl C, having been previously withdrawn i rom engagement with the teeth by means of the pin 7', as previously described, it is obvious that the retraction ot' the blocks G and G/ will cause the lifting-bar to drop suddenly. The yoke-handle ll has an additional important function that should be mentioned, which is that it serves, also, as the handle for lifting the jack, and when the pawl is released by the means provided for that purpose the load may be dropped and the jack displaced by a single exertion ot' force upon the yoke-handle. There are occasions in the use of lifting-jacks, particularly on railroads, when facilities for speedy release of the load and removal of the jack are very desirable, and my construction is peculiarly adapted to fulfill this requirement.

The remaining feature to be described is the mechanism by which the bar may be lowered gradually, notch by notch. To effect this, it is obvious that the blocks G G/ and the pawl C must operate to engage and release the lifting-bar alternately-that is to say, a tooth of the ratchet of t-hc lifting-bar being upon the upper end of the pawl the lifting-bar can be lowered for a certain distance by raising the socket-handle, provided the blocks G G' are retracted during the time the handle is raised, and if then the blocks are caused to re-engage the ratchetof the lifting-bar, and if by lowering the socket lever the pawl is caused to pass upward clear of the teeth and engage another one higher than the previous one it is obvious that the lowerin operai ion may be repeated until the liftin g-bar reaches its lowest point. The purpose of the mechanism about to be described is to permit this operation to bc performed automatically by the mere operation of the hand-lever.

I is a crank-shaft extending through the easing from side to side and projecting therefrom at one side and K is an arm rigid upon the projecting end and which serves as a switch. Upon the outer face of the switcharm is a fiat spring p2, through which and through the arm a loose stud k passes, the spring having a eontraryaction from that ot' TOO TIO

the spring p previously described as being upon the yoke-handle H-that is to say, while the tendency of the spring p was to hold the pin 7c outward, the tendency of the spring p2 is to press the pin 7d inward. The switch only has two positions for operation, these being shown by the full and dotted lines in Fig. 4, and at these points the wall of the standard is recessed to receive the end of the pin and hold the switch in place, as indicated at z'- in Fig. 5. Loosely mounted upon the horizontal portion of the crank-shaft I, by means of a sleeve L, is a bell-crank lever L L2, the arm L' projecting downward near the side of the standard and the arm L2 projecting upward at the center thereof between the blocks G G', which are recessed to receive it, and resting upon a cross-pin r3. Depending` from the same horizontal portion of the crank-shaft I is a loose arm M, having jointed thereto an extension M, guided between two pins r4 and r, projecting from the wall of the standard and havin g also jointed to it a hook-arm M2, which rests upon the pin T5 and the function of which, when the parts are properly set, is to serve as a deector for the pawl, causing` it to clear a tooth of the lifting-bar in its upward movement and engage the bell-crank lever to retract the holding-blocks. Projecting from the upper end of the pawl C is a ange N, provided with a stud r6, which projects over the hook-arm M2. These parts, in conjunction with others that have been described, after the switch has been properly set, automatically operate to lower the bar gradually by the simple Working of the socket-lever in the following manner:

Let it be supposed that the parts are in the inactive position shown in Figs. l and 2 and that it is desired to lower the bar gradually. The first step necessary is to throw the switcharm K to the position represented by the full lines in Fig. et. The effect of this is to rock the crank-shaft I to the position shown in Fig. 3, and this carries the lower arm of the bellcrank lever L L2 immediately over the stud r, upon the flange of the pawl C, and also carries the hook-arm M2 toward the liftingbar and changes its angle from a downward deflection, as shown in Figs. l and 2, to an upward deflection, as shown in Fig. 3. If, then, the socket-lever is raised, the stud r6 engages the inclined end g of the hook-arm M2 and passes down into the notch f of the hook, thus carrying the upper end of the pawl C away from the ratchet-teeth of the liftingbar in opposition to the spring p. During all this period the bar is retained by the blocks G G. Now by depressing the socketlever, the pawl C of course rises, but it is still held out of contact with the ratchet of the lifting-bar by means of the hook-arm M2, and when the stud r6 has cleared the hook-arm it strikes against the lower arm L' of the bellcrank lever and trips it, causing the upper arm L2 to bear against the end of the recess provided for it in the blocks G G and retract them. The parts are so adjusted that at the instant the blocks are retracted the pawl engages a tooth of the lifting-bar. Then by raising the hand-lever the pawl descends, carrying with it the freed lifting-bar, and at the same time the retaining blocks approach the lifting-bar, owing to the fact that the bellcrank lever gradually returns to its normal position as the pawl descends; but the blocks do not re-engage the ratchet of the liftingbar until it has been lowered to the extent of one tooth. With the operation of the handlever this is repeated indenitely so long as the parts are left in the active position indicated in Fig. 3. By throwing the switch back to the position indicated by the dotted lines in Fig. 4 the lifting-j ack is restored to its normal condition.

In order that my invention might be clearly understood, I have found it necessary to describe the parts thus in detail. It is obvious, however, that various details might be modified by the exercise of ordinary mechanical skill, and I therefore do not desire to be limited to the particular construction of subordinate or auxiliary parts, except in so far as they may be specifically set forth in the claims. It should be observed that the main purpose of employing two retaining-blocks G G is to render practicable the differential teeth thereon, hereinbefore referred to. This, however, though desirable, is not indispensible to the device, and where the feature is omitted it is obvious that a single retaining-block maybe employed. My claims are therefore intended to include this construction. The subordinate features of the mechanism for effecting gradual lowering of the lifting-bar may also be modified in various ways without departing from my invention, the essential features of the combination being the adjustable deiiector for the pawl and the tripping-lever engaged by the pawl in its upward movement to retract and return the retaining device at the proper time. As to the compound-lever mechanism intermediate between the pawl and the hand-lever, it should be understood that the duplication of the members, while desirable, is not a necessary construction under all circumstances.

What I claim as new, and desire to secure by Letters Patent, is

1. In a lifting-jack, the combination with a standard, a ratchet lifting-bar, and a retaining device for holding the lifting-bar in raised position, of means for lifting the bar, comprising a pawl, a hand-lever fulcrumed to the standard, a link E pivotally connected to the hand lever and pawl, and a supporting link, pivotally connected with the standard, and also pivotally connected with the link E on a different center from that which connects the latter with the pawl, substantially as described.

2. In a lifting-jack, the combination with a standard, a ratchet lifting-bar, a spring-actuated pawl normally in engagement with the IOO IIO

IZO

lifting-bar, lever-mechanism for raising the' lifting-bar through the medium ot the pawl, and a retaining-deviee normally in engagement with the liftingbar,of means forpermitting the dropping of the lifting-bar,consisting of an extension upon the pawl projecting through a slot in the standard, whereby the pawl may be withdrawn from engagement with thelifting-bar,a11d an accessible lever engaging with the retaining-device to retract it, and terminating in an accessiblehandle available both for tripping the retaining-device and lifting the jack substantially as described.

3. ln combination with a lifting-jack, comprising a standard, a ratchet litti11 'l)a1, a spring-awtuated pawl normally in engagement with theliftingbar,levermechanism t'or raising the lifting-bar through the medium of the pawl, and a retaining-device normally in engagement with the lifting-bar, for holding the latter in raised position, mechanism ,for gradually lowering the lifting-bar by the operation of thehand-lever, consistingot' an adjustable detleetor, operating to cause the pawl in its upward movement to clear a tooth ot the lifting-bar and engage another, and adjustable lever-mechanism, engaged by the pawl in the same upward movement, and operating to retract the retaining device duringr the upward movement ot the pawl, thereby freeing the lifting-bar and permitting it; to descend to the extent ot one notch each time the pawl is lowered, substantially as described.

l. ln a lifting-jack comprising a standard, a ratchet lifting-bar, a spring actuated pawl, normally in engagement with the lifting-bar, lever-mechanism for raising the lifting-bar through the medium of the pawl, and a spring actuated retaining-device, normally in engagement with the lifting-bar, mechanism for gradually lowering the lifting-bar, consisting ot' a crank-shaft I, mounted in the standard, switch-arm K for rocking the same, bell-crank lever I/ L2, loosely mounted on the (frank-shaft and having its upper arm L2 supported adjacent to the retaining-device to engage and retract the same when tripped, pendent arm M, mounted loosely upon the crank-shaft,- l, and having jointed to it the guided extension ill and jointed hookarm M73, in combinatimi with the flange N and pin fr upon the pawl, substantially as described.

\\'Al/l`l 1l S. MCKINNEY.

ln presence of- M. J. FROST, J. lI. LEE.

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