US1523369A - Lifting jack - Google Patents

Description

1 S. SELDEN Jan. 13, `1925.

LIFTING JACK Filed July 19. 1923` 2 Sheets-Sheet 1 INVENToR. 5. Se/deh Jan. 13, 1925.

1,523,369 s. sl-:LDEN 1 LIFTING JACK Filed July 19, 1925 2 sheets-sheet 2 INVENTOR.

Vin the county of Denver Patented Jan. 13, 1925.

UNITED STATES PATENT OFFICE,o

SAMUEL SELD'EN, OF DENVER, COLORADO, ASSIGNOR OF ONE-THIRD TO' CHARLES SELDEN, OF BALTIMORE, MARYLAND.

LIFTING JA CK.

Application filed July 1'9, m23. Serial No. 652,584.

T0 alt trimm t may concern.'

Be it known that I, SAMUEL SnLnnN, a citizen of the United States, residing at Denver,

and State of Colorado, have invented certain new and useful Improvements in Lifting Jacks, of which the following is aspecification.

My invention relates to lifting jacks and iniore particularly to certain new and useful in'iprovements in lever jacks of the type shown and described in my United States Patents Nos. 1,413,792 and 1,413,793, issued on the 25th day of April, 1922.

In the patents above referred to, a mechanism. for reversing vthe movement of the lifting barby the lever action, in both a single action jack and a double action jack, is mounted on al sliding block which is adjusted from one determinate position to another through the instrumentality of an eccentric provided with thumb wings on the outside of the standard in which the lifting bar is supported.

It has been found that especially in lifting jacks of small proportions, the above described reversing mechanism, is unnecessarily complex and it is the principal object of the present invention to provide Vmeans jt'or operating` the reversing mechanism o1c lifting jacks oi the Ytypes disclosed in the above mentioned patents, which combines extreme simplicity of construction with ease ot' operation and practicability in use.

I attain this object by the provision of a lever of the second class upon which the springs which control the movement of the lifting and retaining pawls of the jacks are mounted, and it-is a further object of my invention to provide both pawls with weights for the purpose of insuring their constant operative position relative to the rack bar of the jack.

In the accompanying drawings in the several views of which like parts are similarly designated,

Figure 1 represents an elevation of a lifting jack of the double acting type to which the improvements are applied;

Figure 2, a section on the line 2-2, Figure v1;

Figure 3, an enlarged elevation of the operating mechanism of the jack shown in Figure 1, in the reversed position;

Figure 4, a similar view showing the improvements applied to a jack of the single action type;

Figure a similar view of the mechanism shown in Figure et, in the reversed position;

Figure a transverse section on the line G-G, Figure l g Figure 7, a section taken in the plane indicated by the line 7 -7 in Figure 2;

Figure 8, a side elevation of the adjusting lever employed in a jack of the double action type;

Figure 9, an edce view of the same looking` in the direction o the arrow A in Figure 8,'

YFigure 10, an elevation of the reversing lever of the jack of the single action type shown in Figures i and 5; I

Figure 11, an edge view looking in the direction oi' the arrow B; and

Figure 12, an enlarged fragmentary section on the line 1.2 12, Figure 1.

Referring first to the views of the drawings representing a jack o'f the double action type, the reference character 5 designates a standard oif conventional form and construction in which a rack bar (i has a sliding movement.

The standard is enlarged at the toothed side of the rack bar to provide a housing T for the reversing mechanism and this housing which is open at one side ot the standard. is normally closed by al lid 8 hinged at its lower end as at 9, and fastened at its upper end hy means of a cotter pin 10 inserted through alined openings of adjoining lugs on the standard and the lid.

The operating lever 12 of the jiack, composed as usual, of a metal socket 13 and a wooden handle 14, is fulcrumed on the standard by a transverse pin 1.3 and it has two shoulders 16 and 17 which limit `its reciprocating movement by engagement with the standard and one of the lifting pawls hereinafter to be described.

Two lifting )awls 1S and 19 pivotally sup` ported upon tie portion of the socket inside the housing, are positioned with relation to the rack bar 6 to engage the teeth thereof one above the other.

The pawls are provided at their upper v ends with comparatively heavy weights 18"L and A19a which move in the space between the rack bar and the closed side of the standard as shown in Figures 2 and 7.

The weights function in the operation of thejaclr to constantly maintain the pawls in engagement with the teeth of the rack bar even though the standard is set out of the perpendicular.

To lift a load supported on the rack bar, the downward stroke of the lever 12 causes the lower and shorter pawl 19 to raise the bar while the other longer pawl 13 rides idly across thetcet-h thereof, and when the movement of the operating lever is reversed, the upper pawl is forced to act upon the raclr bar while the other pawl returns to its` original position.

The reversing mechanism of the jack which adjusts the pawls to alternately sustain a load on the rack bar while it is being lowered, comprises two spring members 20 and 21 preferably formed of one piecev of metal, which in the operative position of the reversing mechanism are respectively engaged by studs 22 and 23 projecting laterally from the two lifting pawls.

In the present invention these two spring members are riveted to a lugl 24 projecting laterally from a lever 25 which at its lower extremity is fulcrumed on a pin 26, projecting from a part of the standard inside the housing.

The lever 25 which is bent in order to place the springs in operative relation to the studs ou the pawls, projects at its free end through a slot 27 in the upper portion of the housing. The slot has in one of its edges two notches 28 and 29 best shown in Figure 12, and the lever is provided with a laterally projecting detenty 30 which in co-operation with the notches locks the lever in one or the other of its adjusted positions.

The detent is held in place in the notches by the inherent resiliency of the lever which at itsl lower end bears upon across pin 51 inserted through an aperture in the end of of the pin on which it is fulcrumed.

The spring member 2O curves upwardly and extends below the stud 22 on the pawl 18 and the lower spring 21 which extends partially over the stud 23 of the pawl 19 has a reversely bent end portion extending slantingly beneath the same.

Then the jack is used to lift the load, the

lever 25 is in its extreme forward position with relation to the rack bar as illustrated in Figure '3, and the two springs are out of the paths of travel of the studs on the pawls when by movement of the operating lever 12, the pawls are caused to alternately act upon the teeth of the rack bar as hereinbefore described, it being understood that the weights on the pawls constantly hold them in their operative position.

Vhen the jack is employed to lower its load, the lever 25 is moved to the position illustrated in Figure l, to compel the pawls to alternately sustain the weight during the reciprocating motion of theoperating lever 12. This result is produced through the instrumentality of the springs, it being evident that when the operating level` is reciprocated, the springs are alternately engaged by the `respective studs on the pawls and so defiected that at the termination of each stroke of the lever one ofthe pawls is forced out Ef engagement with the teeth of the rack ar. Y

Inasmuch as the action of the springs on the pawls is the same `in this construction as 1n the mechanism described in Patent No.

explanation is thought to be sufficient to'give a clear understanding of the operation ofthe element forming the subject of the present invention. Y

The operating lever has been shown in Figure 1 in its lower position and in Figure 3 in its upper position, to showv the positions assumed by the pawls andthe springs in the operation of the jack.

In the single action ,lifting jack, the up-` When the jaclr .is used to lift its load andv the operating lever is in its position of rest both pawls engage the teeth of the rack bar and thus co-operate tohold it in lits adjusted position and when the jack is adjusted to lower the load, the'two pawls al- 1,413,793 hereinbefore referred to, the above j ternately sustain the load and are alter-v nately released from the teeth of therack bar through the instrumenta-lity` of the springs included in the reversing mecha-V nism. l

TheV reversing mechanism of the single acting jack differs from that of the'double action 'jaelr hereinabove described, prin-` cipally in that it includes a dog 34 which isV pivoted on a lever 35 similar tothe lever25 of the double action jack, and to which the upper spring member 36 is attached The dog rests Vnormally on a shelf 3T formed at the side of the lever; it is pivoted on an ear ofthe lever as Vat 38 'and itis guided in its upward movement by apin 39 on an opposite ear of thel lever, projecting into a curved slot oftheear.

The dog has at its free end a head 4Q. pro;

Vvided on its"underside with a slanting face 4l which in the operation of the reversing mechanism is engaged by a stud 42 of the lifting pawl 38.

The lower spring member 43 is fastened to a ridge 44 on the lever below the shelf 37, and it engages in the oper-c tion with a second stud 45 on the lifting pawl 33.

Then the jack is used to lift its load as shown in Figure 4 of the drawings, the lever 35 is in its upper position in which it is held by the engagement of its detent 46 with the upper notch of he slot in the housing 7 as before, the dog 34 is in its normalposition, supported on the shelf 37 and the two springs are out ofthe paths of travel of the studs on the two pawls as in the double acting j acl: hereinbefore described.

IVith the parts thus positioned the downward movement of the lever l2 Causes the rack to be lifted by the pawl 33, and the retaining pawl 3l holds the rack and its load in position when the operating lever is subsequently raised.

In order to place the jack ina condition for lowering the load supported on its rack bar, the lever 35 of the reversing mechanism is moved to its lower position illustrated in Figure 5 in which its detent engages the lower notch of the slot in the housing.

lilith the operating lever l2 of the jaolr in its normal position of rest, the adjust ment of the lever 35 of the reversing mechanism, causes th-e slanting face 4l of the head of the pivoted dog to ride across the upper stud 42 of the lifting pawl 33, thereby mov ing the dog upwardly about its pivot, until its head rests upon the-stud as shown in Figure 5. j

The spring 36 is by the upward movement of the dog, pressed against the stud47 of the retaining pawl 31 so that when by further downward movement of the operating lever, the pawl is released from the weight of the 4load on the rack bar, the bent spring will cause the pawl to disengage the teeth of the bar and thereby permit of the bar being lowered with the lifting pawl when the lever is subsequently raised.

During the downward movement of the pawl 33, its stud 45 engages the reversely bent portion of the lower spring 43 while the dog gradually reassumes its normal position and releases the upper spring 36 from the stud 47 on the retaining pawl 31, and at the time the upward movement of the operating lever is completed, the spring 43 gradually deflected by the stud 45 on the pawl 33, disengages the pawl from the teeth of the rack bar, while the retaining pawl engages the rack bar to sustain the load.

Having thus described my invention, what I claim and desire to secure by Letters atent is:

1. In a lifting jack, the combination of a movably mounted rack bar, a lifting pawl and a retaining pawl engaging the teeth of the rack bar, an operating lever in operative relation to the lifting pawl, and a reversing mechanism comprising a reversing lever adapted to be adjusted from one to another of two determinate positions, and springmembers on the reversing lever disengaged from the pawls in one position of the lever and adapted to engage with the pawls in the other position of the same to alternately lift them out of engagement with the teeth of the rack bar in the operation of the jack by movement of the operating lever.

2. In a lifting jack, the combination of a housing having a slot provided with notches, a rack bar movable therein, a lifting pawl and a retaining pawl engaging the teeth of the rack bar, an operating lever in operative relation to the lifting pawl, and a reversing mechanism comprising a reversing lever fulcrumed on the housing and adapted to be adjusted from one to another of two determinate positions, a detent on the reversing lever, (zo-operating with the notches of the slot vin the housing, to automatically loek said lever in its adjusted positions, and spring-members on the reversing lever disengaged from the pawls in one position of the lever and adapted to engage with the pawls in the other position of the same to alternately lift them out of engagement with the teeth of the rack bar in the operation of the jack by movement of the operating lever.

3. In a lifting jack. the combination of a movably mounted rack bar, pawls engaging the teeth of the rack bar, an operating lever in operative relation to said pawls, and a reversing mechanism comprising a reversing lever adapted to be adjusted from one to another of two determinate positions,

and spring-members on the reversing lever disengaged from the pawls in one position of the lever and adapted to engage with the pawls in the other position of the saine to alternately lift them out of engagement with the teeth of the rack bar in the operation of the jack by movement of the operatingI lever.

4. In a lifting jack, the combination of a movably mounted rack bar, weighted pawls engaging the teeth of the rack bar, an operating lever in operative relation to at least one of said pawls, and a reversing mechanism comprising a reversing lever adapted to be adjusted from one to another of two determinate positions, and springmembers on the reversing lever disengaged from the pawls in one position of the lever and adapted to engage with the pawls in the other position of the same to alternately lift them out of engagement with the teeth of the rack bar in the operation of the jack by movement of the operating lever.

loo

ai; 1 ,sassee In a lifting' jack, the combination of a movablfy mounted rack bar, Weighted paivls engaging the teeth of the `rack bar, an operating lever in operative relation to at least one of said paivls, vand a lreversing mechanism comprising an adjustable member and springs on said member normally disengaged from the pawlsand adapted to Vengage the paivls in an adjusted position of' the member to alternately force them Vont of engagement with the teeth of the rack bar in the o-peration of the jack by movement of the lever.

(3. In a lifting jack, the combination of a movably mounted racl bar, a. lifting p'aivl and a retaining paivl engagingthe teeth of the rack-bar, an operating lever in oper-V ative relation to the lifting pand, and a -reversing mechanism comprising Ia reversing lever adapted to be adjusted from one to another of tivo determinate positions, a dog pivfoted on the reversing lever and disposed in the path of a part of the lifting paivl to be raised thereby in an adjusted position of the reversing leve-r, a spring carried by the dog, and a spring carried by the reversing lever, said springs being disposed to engage respectively with a part of the .retaining 'paivl and with a ,part of the llifting paWl when the vreversing lever is in its said adjusted posit-ion, to alternately lift them lout of engagement with the. teeth of therack in the operation of the jack by movement of the operating lever.

7. In a lifting jack, the combination of armovably mounted rack bar, .a lifting pawl and a retaining pawl engaging the teeth of the rack-bar, an operating lever in operative relation to the iifting pawl, and a. re-

versing mechanism comprising a reversing lever adapted to be adjusted from one to another of two `determinate positions, a dog supported in its normal positionon the reversing lever .in the path of .a partY of the lifting `paivl and having aVV pivotal movement on the same to be raised by engagement with a part of the lifting paivl in an adjusted position ofthe reversinglever, a spring vcarried by the dog, and a spring carried by the .reversing lever, said springs being `disposed to engage respectively with a part of the retaining paivl and with a part of the lifting paivl when the reversing lever is in its said adjusted position, to alternately .lift them out of 'engagement With the teeth of the rack in the operation of the jack by movement of the operating lever. 111

8; In a lifting jack, the combination of a movably mounted rack bar, a vlifting pawl and a retaining paWl engaging the teeth of the rack` bar, an operating lever in operative relation to the lifting paWl,` and a reversing mechanism comprising a` reversing lever adapted to be adjusted from one to another of two determinate positions, a dog supported in its normal position by the reversing lever-in the path ofa part fa.

of the lifting paWl and having a guided and limited Ypivotal movement on the same to be raised by engagement with apart of the liftingpaWl in an adjusted positionof the reversing lever, a spring carried by the- 1 dog, and a spring carried by the reversing lever, said springs beingdisposed to engage respectively with Ya part of the retaining pawl and With a part of the lift-ing paivl when the reversing .lever is in .its said adi signature.

v SAMUEL SELDEN.

jack by movement of

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