US399470A - Lifting-jack - Google Patents

Description

(No Model.) 3 Sheets-Sheet 1.

JQ BARRETT. LIFTING JACK.

No. 399,470. Patented Mar. 12, 1889.

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Hu um wil-masses: INVEN'roR,

(No Model.) 3 Sheets-Sheet 2.

J. BARRETT.

LIFTING JACK. i No. 399,470. Patented Mar. 12, 1889.

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(No Model.) 3 Sheets-Sheet 3.

J. BARRETT.

LIPTING JACK. No. 399,470K Patented Mar.. 12, 1889.

WITMESSES: INVENTOR,

NTTpn STATES ATTENT Tries.

.10811111 HARRE'IT, Olf ATALEGHEN'Y, PENNSYLUXNTA,

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SPECIEFCATION forming part of Letters Patent No. 399,470, dated March 12, 1889.

Application tiled October 26, 1888. Serial 110.289,196, (No modela lle it known that I, JOSIAH BARRETT, a eitizen ot the United States, residing at Allegheny, in the county of' Allegheny and State ot' Pennsylvania,have invented or discovered a certain new and useful Improvement in Li'li'ting-Jaeks, ot' which the following is a specification.

The invention described. herein relates to certain improvements in that class of power meehanism wherein a step-hy-step movement haelt: and forth is required, said mechanism being actively oliierative in one direction to move or raise a load and passively operative, as it were, in the opposite direction to control the movement et" a load. For the purposes ot' this ease l have seleeted a lifting-jack as one [orm of power meehauism embodying my invention.

l'n general terms, the invention consists in the oonstrmi-tion and eomhination of mechanieal devices or elements,all as more fully hereinalter desrrihed and claimed.

ln the aeeompanying drawings, vforming a part ol.' this speeiiieaiion, Vlligure 1 is a view in side elevation ol' a lifting-jack embodying my invention, the rap-plate ol' the jack being removed to show the arrangement of the pawls and their eonneetions. Fig. 2 isa similar view of the opposite side ot' the jack, the side plate being broken away to show the arrangement ol' the releasiiig-dog. Figs. 25 and -t are diagrammatic views showing the operation ot' the pawls in lowering the lifting-bar. Fig. is a detail view ot' the inner l'aeeol' the tripping-plate. Fig. o is a detail view ot the detent or holding-pawl, and l1`ig. 7 is a detail view of a portion ot' the traine, showing the operation of the releasing-dog.

As described and shown in Letters Patent No. 312,316, granted lflebruary 17, 1835, the trame Il. formed with a longitudinal reetangularly-shaped passage forthe reception of the bar 2, which may be provided at its lower end with a toe, Si, projecting out through a slotin one side ot' the frame and extending about two-thirds of the length of the frame. Along the edge of the frame or stand opposite that provided with the slot, as above stated, is formed. a (lange, 1, provided at its lower end with an abutmeiit, 5, said abutment and flange forming a soeket for the reception of the inner end oli' the operating-lever C. This lever is pivotally mounted on a pin, 7, passing through the sides oi? the socket in the trame 1, and to said lever, at a point forward of its fulerum, is pivoted a pawl, S, arranged to engage the ratelnat-teet-h formed along one side of the bar 2. A holdng-pawl or detent, S), is pi votally mounted on a pin, 10, passing through the sides of the socket, said detent being arranged outside ot' the pawl 8 and arranged to engage the teeth on the bar 2 at a point above the pawl S. The pawls 8 and t) are held normally in engagement with the ratchet-teeth on the har 2 hy levers 11 and lhpivoted to said pa-wls a short distance above their fulera, as shown in Figs. 1, 23, and '-1.

Around the pivotal pins of the levers 11 and 12 are arranged the coiled springs 13 and 113, one end of each of said springs being conneeted to the levers at or near their upper ends, the opposite end ot' said springs heilig Connected to the pawls, as shown in Fig. These springs are arranged to foree the upper ends of the levers outwardly, or to the right, and the lower ends thereof inwardly, or to the left, as shown in Fig. 1; but as the outward niovemel'its ot` the upper ends are prevented by a shoulder or stop, 1-1, on the frame or stand, the lever 1,2 bearing against said stop, and a projection, 15, on the lever 11 bearing against the lever l2, the lower portions of the levers are t'oreed inwardly, or to the lelt, thereby moving the pa-wls into engagement with theratehet-teeth on the bari. Alifting-jaek Constructed as hereinheiore deserihed does not differ materially from the ordinary torm ot' pawl-and-ratchet jack, the lifting-bar being raised during the downstrolce ot the operating-lever G, and held in such raised position by the pawl or detent il during the upstroke of said lever, the pawl 8 and detent S) being held against the ratchet-teeth of the lifting-bar by the spring-levers 1lA and 1i.

ln order to lower the bar or permit its n'iovement under the action of the load, the above-described operation of the pawls must be reversedi. e., the pawl or detent .l must be held away 'from the har 2 during the upstrolce oi the operating-lever and caused to TOO engage one of the teeth of the bar at the end of such stroke, while the pawl S must be held away fronr the ratchet-teeth during the downstroke of the lever, and at the end of such downstroke must engage one of the teeth of the bar 2 and retain such engagement until the end of the upstroke, when it is forced out of engagement with the ratchet-teeth again. It will be understood that the ou ter end of the lever 6 is referred to in the above statements as to the directions of stroke. This reversal of the normal operation of the pawl and detent is effected by the tripping-plate 16, (see Fig. 5,) provided on its inner faces with a projection, 17, having a suitably-shaped camsurface for engagement with the lower end of the lever 11 and with a bearing point or stop, 18,'for engagement with the auxiliary or releasing lever 19, pivot-ed on the lower end of the lever 12, as shown in Figs. 1, 3, and a. This tripping-plate is pivoted at its lower righthand corner to the abutment 5 of the stand or frame, as shown in Fig. 1, and is supported at its lower left-hand corner by an eccentric, 20, fitting within a notch in said plate and mounted on a pin, 21, screwing into the stand or frame. During the normal or lifting action of the jack the plate 1G is so held by the eccentric that the projection 17 and stop 18 are out of the paths of movement of the lever 11 and the auxiliary or releasing lever 19, as shown in Fig. 1; but when it is desired to lower or permit the bar 2 to be shifted the eccentric 2O is so turned by means of the wings thereon as to move the plate upward and to the right, thereby bringing the ,projection 17 and bearing point or stop 1S into operative relation with the lever 11 and the auX- iliary or releasing lever 19. By reference to `Figs. 3 and #l the operation of the trippingplate 1G, thelevers 11 and 12, and the releasing or auxiliary lever 19` in disengaging the pawl i ,8 and detent 9 will be clearly understood, it

being premised that in Fig. 3 the operatinglever ti is shown at the lower limits of its stroke, the pawl 8 being in engagement with the ratchet-teeth of the bar 2, and the detent 9 being held away therefrom, while in Fig. 4 the operating-lever is shown at the upper limits of its stroke or movement, the pawl S being held away from the lifting-bar and the detent 9 in engagement therewith. As the lever G is raised, thereby lowering the inner end thereof, and with it the pawl 8, thebar 2 will be correspondingly lowered, the detent 9 being held from engagement with said bar by the auxiliary lever 19, one end of which bears upon the stop 1S of the cam-plate 16, and the other end upon the pivot-pin S of the lever 11, or other suitable bearing-point movable with the pawl S. As the pawl S descends, the lower end of the lever 11 thereon will come into contact with the cam projection 1 7 on the plate 1G and be forced outward against the tension of the spring` 13, which serves, when the upper end of the lever 11 is held as against outward movement by engagement with the lever 12, to force the pawl S inward into engagement with the teeth on the bar 2, as hereinbefore stat ed. It will be readily understood from the above that the outward movement of the lower end of the lever 11 applies an outwardly acting but yielding pressure to the pawl S proportional to the tension of the spring 13, such pressure being operative to shift the pawl as soon as it is relieved of the weight or pressure of the bar and its load, in the mannerhereinafterdescribed. As shown in Fig. 3, the inner end of the auX- iliary lever 19 rests upon the pin S, and will therefore be lowered during the downward novement of the pawl S, thereby permitting of the inward movement of the lower end of the lever 12, and with it the detent 9, actuated by the spring 13, the upper end of the lever 12, to which one end of said spring is connected, bearing against the stop 1a. The devices governing this inward movement of the detent 9 are so constructed and arranged that the detent will engage one of the teeth of the bar 2, and prevent further downward movement thereof a little before the lever G completes its full upward movement, thereby relieving the pawl S of the weight or inwardlyacting force of the bar and its load, and permitting of said pawl being forced outwardly by the spring 13, as hereinbefore stated. During the downward stroke of the .lever C the pawlS will be raised, thereby permitting of the gradual release of thelower end of the lever 11 from engagement with the cam projection 17, and theeonsequent forcing of the upper end of said lever outward to a bearing upon the lever 12, and after such a bearing has been effected the forcing-,inwardly of the lower partof said-lever and the pawl S bythe spring 13. As the pawl 8 moves upward, the pin 8 raises the inner end of the auxiliarylever 19, thereby forcing the lower end of the lever 12 outward and the upper end thereof inward away from the stop l-l against the tension of the spring' 13". This changing of the bearing-point or fulcrum of the lever 12 from its upper to its lower end subjects the detent 9 to an outwardly acting and yielding presslOO IIO

ure sufficient when the detent is relieved of the weight of the bar 2 and its load, to force the detent away from the lifting-bar.

The above-described parts controlling the movements of the pawl S are so constructed as to permit of the engagement of said pawl S with one of the teeth of the bar 2 a little before the completion of the downward stroke of the lever G, and hence a slight upward movement is imparted to the bar at the completion of the downstroke, thereby relieving the detent of the weight of the bar and its load, and permitting of the outward movement.of the deten t, as above described.

In some cases it is desirable to disengage the pawl and detent simultaneously, so as to drop the bar and its load suddenly; and to this end a releasing-dog, 22, is pivoted to the pawl S on the side opposite the lever 1.1, as

shown in lfigs. 2 and 7, said dog beingl pro vided with a notch in its free end adapted to engage a shoulder or proj eetion, 23, formed on the inner wall of the recess containing the operating mechanism.

The dog and shoulder are so arranged with reference to each other and the function to be 'eltected that when the pawl S is at the lower limit of its movement the notch in the end of the dog will engage the shoulder or projection 23; hence as the pivotal point of the dog is below the shoulder when the pawlS is lowered said pawl will during its upward movement be forced outward clear of the teeth on the bar, and coming in contact with the detent SJ will also force it out ot engagement with the bar. During the normal operation of the jack the dog is turned back and rests upon a projection, 24,011 the inner wall of the frame. The dog is shifted into and out of operative position by a pin, 25, thereon, said pin. projecting through an opening in the wall of the recess in the trame, as shown in lfig. 7.

Although l have shown and described my invention as applied to lifting-jacks, it ,will be understood that the mechanism hereinbel'ore described can be readily applied to other purposes without departing from the spirit ot my invention.

l claim herein as my inventionl. A toothed bar, in combination with a pivotal lever, a pawl pivoted to said lever, a detent pivoted. to the frame, and spring-actuated. levers pivoted to said pawl and detent, and hav ing their upper ends rigidly supported as against the action of their actuatingsprings, substantially as set forth.

2. A toothed bar, in combination with a pi voted operating-lever, a pawl pivoted to said lever, a detent pivoted to the frame, springactuated levers pivoted to said pawl and detent, an auxiliaryv lever pivoted to the lower end of the spring-actuated lever on the d etent, a stud or projection 011 the pawl adapted to engage one end ot the auxiliary lever, a movav ble tripping-plate having a cam-lug, and a stop or shoulder respectively adapted in certain positions of the plate to engage and shit't the lower end ot the pawl and to hold one end of the auxilary level-as againstinward movement, substantially set forth.

I5. A toothed bar, in combination with a pivoted operatin g-lever, a pawl, pivoted to said lever, a detent pivoted to the frame, springactuated levers pivoted to said pawl and detent, an auxiliary/'lever pivoted to the springactuated lever of the detent below its pivotal point, and a stud or projection on the pawl adapted to engage one end of the auxiliary lever, the levers on the pawl and detentbein so arranged, as described, that when rigidly at their upper ends, as against the action ot' their springs, they will operate to hold the pawl and detent against the toothed bar, and when the lower end of the pa-wl and the ends of the auxiliary lever are similarly supported they will cause the pawl and detent to move away from the toothed bar, substantially 4as set vforth.

4. A toothed bar, in combination with a pivoted operatingdever, a spring-aetuated pawl pi voted to said lever, a spring-actuated detent pivoted to the stationary frame, said detent being arranged outside of the pawl, a tripping-dog pivoted to the pawl, and a stop or shoulder on the frame wit-h which said dog l can in certain positions engage and operate to i'orce the pawl and detent away from the toothed bar, substantially as set forth.

In testimony whereof I have hereunto set my hand.

.'lOSlAll PARRE'l'l. XVitneSses:

DARWIN S. WoLcoTr, R. 1I. 'WHITTLEsnv-

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